MXPA00011697A - Method and device for detecting analytes in fluids - Google Patents

Abstract

A disposable, dry chemistry analytical system is disclosed which is broadly useful for the detection of a variety of analytes present in biological fluids such as whole blood, serum, plasma, urine and cerebral spinal fluid. The invention discloses the use of the reaction interface that forms between two liquids converging from opposite directions within a bibulous material. The discovery comprises a significant improvement over prior art disposable, analytical reagent systems in that the detectable reactant zone is visually distinct and separate from the unreacted reagents allowing for the use of reaction indicators exhibiting only minor changes as well as extremely high concentrations of reactants. In addition, staged, multiple reagents can be incorporated. Whole blood can be used as a sample without the need for separate cell separating materials. Finally, the invention is useful for the detection of analytes in a broad variety of materials such as milk, environmental samples, and other samples containing target analytes.

Description

METHOD AND DEVICE FOR DETECTING ANALYTS IN FLUIDS The present application is a continuation application in part of the pending US patent application 09 / 439,024, filed on November 12, 1999, which was a request for continuation in part of the US patent application serial No. 09 / 277,715, filed on March 26, 1999.

FIELD OF THE INVENTION The present invention relates to test devices and methods for the determination of analytes that may be present in liquids.

BACKGROUND OF THE INVENTION It is important to quantify chemical and biological components in aqueous sample solutions, such as whole blood, plasma, serum and urine, for the timely and correct diagnosis of various diseases, as well as monitoring the progress of medical treatment of diseases. In many cases, analytes are present that are to be measured only in minute quantities and are often mixed with very large amounts of irrelevant or interfering components. Some components, such as red blood cells, obstruct the analysis of the sample, if present. Reagents and indicators used to detect and measure analytes, which are often highly colored and closely resemble the reaction products in terms of their absorbance spectra, are also problematic. Additionally, the measurement of analytes frequently requires multiple, incompatible reagents, which must be stored separately and added sequentially. Any of these factors can complicate the detection and quantification of analytes in fluid samples. These problems and cases have been faced in many ways. The analytical methods used in clinical chemistry tests and other used applications can be divided into two broad categories of analytical formats: liquid chemistry formats and dry chemistry formats. Liquid chemistry systems require that the sample and liquid reagents be dispensed into reaction chambers in a sequential synchronized order. Samples should be diluted frequently with special regulators to reduce or eliminate interfering compounds and then added to reagents designed to react with specific analytes. In some cases, the multiple reagents must be pre-mixed immediately before use, due to stability problems. In other cases, additional reagents may be necessary to provide color-producing reactions that can be read. The results can be obtained by measuring the absorption of light by the fluid sample. Reactions involving decreases in the color of the reaction or minimal differences in color change may additionally be required from separate reagent tubes to normalize the results or serve as controls. Dry chemical systems use dried reagents on absorbent surfaces. Very commercially obtainable products have multiple layers of reagents sandwiched together. Some are arranged vertically and some vertical and horizontal combinations. In all cases, dry chemistry systems that use chromogenic reactions are based on measuring the light reflected from the upper surface or from the bottom surface of the final reagent pad. The whole blood test presents additional problems, since it requires a separate method to separate the red blood cells from the sample, such as centrifugation or the use of one or more blood-separating filters, which separate the plasma for analysis. The essence of dry chemistry analysis is to contain a liquid reaction so that the colored reaction products can be visualized. This is done with gels and polymers, for example, Vitros (Johnson &Johnson) or fibrous paper-like materials, for example, Seralyzer (Bayer Diagnostics). In all cases, the reaction between a mixture of sample, diluent, reactants and product must be observed, which can result in difficulties in distinguishing the product from the non-product. In addition, since all or part of the original reagent is consumed, it may be impossible to re-reference the starting material, such as to establish a basic line of reagent. In contrast, the present invention retains all components for further evaluation In the methods that require a precise reaction synchronization, such as those that require rapid reactions or to measure a rate of change, it is often difficult to determine the exact time of the start of the reactions In most cases the functioning of the analysis, and therefore , the safety of the results depends on the possibility that the test system uniformly delivers a certain amount of liquid (usually plasma of blood or serum) to a final reactive material. This material must absorb a known quantity of liquid with extreme precision and capacity. of reproduction, so that the results are useful The measurements The precise volumetric measurements necessary to obtain accurate results with these types of analyzes present particular challenges and make it difficult to work with them. Both liquid and dry chemical systems are limited in the concentrations of reagents that can be used. These concentration limits are often due to the presence of highly colored reagents, which absorb or reflect light at wavelengths that interfere with, or obscure the detection of, the reaction product that can absorb or reflect light at similar wavelengths. Various methods have been employed in an attempt to solve this Hochstrasser problem, in US Pat. No. 3,964,871, describes a disposable indicator for measuring substances, which records the concentration of a substance in a given biological fluid, indicia that can be read directly in a convenient notation, thereby reducing the uncertainty of the comparison with a on a scale of color intensity. Kim and coauthors, in US Pat. No. 4,303,408, describe elements with reducing zones of interferers, which eliminate the interferers before they reach the reaction zone. Despite these attempts, only marginal improvements are possible due to the physical limitations inherent in the methods. U.S. Patent 5,716,852, issued to Yager and co-inventors, teaches a channel-cell system for detecting the presence and / or measuring the presence of analyte particles in a sample stream comprising a laminar flow channel, two inputs in connection with fluid with the laminar flow channel, to drive respectively to the laminar flow channel, an indicator current which may comprise an indicator substance indicating the presence of the analyte particles by a detectable change in the property, when it is brought into contact with the analyte particles and the sample stream. The laminar flow channel has a sufficiently small depth to allow the laminar flow of currents and a sufficient length to allow particles of the analyte to diffuse into the indicator stream, for the substantial exclusion of the larger particles in the sample stream, to form a detection area. An outlet drives the streams out of the laminar flow channel to form a single mixed stream. Yager describes the formation of a reaction interface that is formed between two fluids that move through a capillary tube, in the same direction. The invention of a stable interface that is formed when two liquids meet and stop in a flow matrix after being transported from opposite directions is described. The Yager patent is based on the principle of liquid laminar flow, which was known in the art. By contrast, the present invention employs bibulous material to physically contain the liquid interface. US Patent No. 5,187,100, issued to atzinger and co-inventors, discusses a control solution for use with a porous test strip, and comprises a flexible semisolid polymer, dispersed in water, such as polyvinyl acetate in distilled water, with concentration levels of Appropriate glucose control. This solution is useful for imitating the whole blood in conjunction with the porous test strips to determine the attachment of the strips and the meters to the established criteria of measurement and functioning. U.S. Patent 5,147,606, issued to Charlton and co-inventors, teaches a diagnostic device that detects blood analytes with a sample volume of just 2 microliters, in the hematocrit range of 0% to 60% or more. This is achieved by using a housing with various chambers and compartments to process the blood. A sample application port is used in the housing to introduce blood into a metering chamber. From the dosing chamber, the blood flows to a reaction chamber to analyze the analytes in the blood. The blood entering the metering chamber flows into a capillary of fluid indicating that an adequate amount of blood was received in the metering chamber. The reaction compartment includes a reagent and a filter; the latter arranged between the dosing chamber and the reagent, so that the reagent reacts with the filtered blood. U.S. Patent 4,839,297, issued to Freitag and co-inventors, teaches a test apparatus for the analytical determination of a component of a body fluid with a base layer and at least two flat test layers which, in the initial state of the carrier test, before carrying out the determination, are separated from each other, but can be put in mutual contact by external manipulation. A first test layer and a second test layer are disposed on the base layer, essentially contiguous with each other but separated in the initial state by a gap; a contact element consisting of a capillary active material is provided which is dimensioned in such a way that it can serve as a bridge over the gap and which is mounted and arranged so that, in a first position, it can not make contact with at least one of the test layers; but by external pressure, it can be brought to a second position in which it makes contact with both test layers in such a way that a liquid change is possible between the test layers. US Pat. No. 4,637,978, issued to Dappen, describes a useful analysis. For the determination of an analyte in whole blood In particular this analysis is useful for the quantitative determination of peroxide generators, such as glucose or cholesterol, in whole blood. This analysis uses a multi-zone element, consisting essentially of a support that has therein, in order and in fluid contact, a recording zone and a reagent / diffusion zone The reagent / diffusion zone has a hollow volume and an average effective pore size to accommodate whole blood, and contains an interactive composition, necessary for the analysis This composition is able to provide, by interaction with an analyte, a dye that can be detected Spectrophotometrically at a wavelength greater than about 600 mm. U.S. Patent 5,408, 35, issued to Howard, III and co-inventors, discloses a video reader of test strip that can locate, analyze the color and determine the time, simultaneously, of multiple reagent test strips, such as those used in solid-based clinical analyzes The reader includes a video imager that produces an analog signal that is converted to a digital signal, which represents the image The digital signal is stored in the form of groups of pixels containing color information The digital signal is then processed to calculate the desired test results, such as the concentration of a constituent or other measurable properties US Patent 4,160,008, issued to Fenocketti and co-inventors teaches a test device to determine the presence of a liquid sample constituent The device comprises a base supporting member having affixed an indicator member that produces a detectable response, such as a color change, in the presence of a sample constituent. The indicating member comprises a top layer of reagent, an absorbent bottom layer and a barrier layer substantially impermeable to the sample between the upper and lower layers. The indicating member is fixed to the base member along the underside of the absorbent layer., 042,335, issued to Clement, describes an element of several layers for the analysis of liquids, such as biochemical and biological liquids. The invention includes a reagent layer that includes a composition that is interactive in the presence of a predetermined substance to be analyzed ( ana to) to give a diffusible, detectable species, for example, a dye, to be detected. It is preferred that between the reagent layer and the recording layer there is a radiation blocking layer, such as an opaque reflecting layer, for reinforce the detection of the difficult species within the recording layer A diffusing layer is separated from the recording layer by a reagent layer In operation, a sample of the liquid to be analyzed is applied to the reagent layer, or if present, to a diffusing layer If the sample contains analyte a chemical reaction or other interaction within the reagent layer gives a detectable species that diffuses, by means of any intermediate layers, such as a radiation blocking layer, towards the recording layer for detection there, as by radiometachistic techniques, such as reflection spectrophotometry. US Pat. No. 3,992,158, issued to Przybylowicz and co-inventors, describes an integral analytical element, capable of used in the analysis of liquids, the element having at least two overlapping layers that includes a diffusing layer and a reagent layer, in fluid contact The diffusing layer, which may be an isotropically porous layer, diffuses within itself so less a component of a liquid sample applied to the element, or a reaction product of said component, to obtain a uniform concentration of at least one of said diffusing substances, on the surface of the diffusing layer facing the reagent layer reagent layer, which preferably is uniformly permeable to at least one component dissolved or dispersed in the The liquid, or a reaction product of said component, may include a matrix in which a material is distributed which may interact, for example, with an analyte reaction product or analyte, to produce a detectable change in the element, as one detectable by measurement of electromagnetic radiation In a preferred embodiment, the interactive X 11 material can react chemically with an analyte or anahto reaction product, to produce a color change in the element. In another preferred embodiment, the diffusing layer of sample can filter chemically interfering materials or other undesirable materials, and obtain selective diffusion of the sample components and / or can provide a reflective background, often useful for analytical results US Patent 3,811,840, issued to Bauer and co-inventors, teaches a test device to detect the concentrations of substances in the test fluids, including an absorbent wick having a substantially flat surface portion, encased in a fluid impermeable sheath having an aperture of a predetermined limited area, formed therein. The aperture is contiguous to, and exposes a limited area The predetermined portion of the flat surface portion of the wick, which is incorporated with a reagent specifically reactable with the substance being detected. In use, the device is immersed in the test fluid, so that the opening is submerged and the the device remains there while the The test fluid contacts the reactive area adjacent to the opening and migrates to the remainder of the wick. The reagent is immobilized from the liquid. US Patent No. 4,061,468, issued to Lange and co-inventors, describes a test strip to detect components in liquids especially in body fluids The test strip includes a fastener and at least one indicator layer containing detection reagents. One surface of the indicator layer is fixed to the fastener and the other surface is covered with a fine mesh. However, it is to be noted that prior art analytical devices mentioned above employ fluid movement in only one direction. Because a reaction interface is not created by the movement of two liquids in opposite directions, the references of the prior art, given above, can not be used to measure the intensity of the reaction or the reaction rate in an interface of reaction, as described in the present invention. The present invention provides a solution to the problems and inefficiencies of the current systems, discussed above. Specifically, the present invention provides devices that contain all reagents necessary for sample preparation and analyte detection and methods for their use. The present invention provides devices and methods that eliminate the extreme precision in the volumetric measurement that is necessary by some methods. The results of the analyzes carried out with the present invention are read in a generic reading area of the device and a great variety and versatility is offered in the chemistry of the reagents and in their concentrations.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a device for detecting and quantifying at least one analyte in a fluid sample suspected of containing the analyte, using a liquid reactant capable of reacting with the analyte to form a soluble reaction product. , detectable. The device comprises a fluid transporting material having a first zone ("the fluid sample zone") for the application of the fluid sample at an application site of the fluid sample; and a second zone ("the liquid reactive zone") for the application of the liquid reactant at a liquid reactant application site, where, when the fluid sample is added to the first zone and the liquid reactant is added to the second zone , the fluid sample flows in a first direction from a fluid sample edge to the second zone; and the liquid reactant flows in a second direction, opposite the first direction and towards the first zone from a liquid reactive edge. When the fluid flowing sample is found and the flowing liquid reactant the flow is stopped and the reactants diffuse into each other, and the detectable reaction product is formed by a reaction between the liquid reactant and the analyte, in a Stable reaction interface formed in a joint between the fluid sample and the liquid reactant, and visually distinct from them. In another embodiment the present invention also provides a device for detecting and quantifying at least one analyte in a fluid sample suspected of containing the analyte, comprising a fluid transporting material having a first zone ("the sample zone"). fluid ") for the application of the fluid sample at the application site of the fluid sample; and a second zone ("the liquid reactant zone") for the application of a liquid reactant at a liquid reactant application site, where the reagent and liquid form a liquid reactant containing a reagent capable of reacting with the present analyte In the fluid sample to form a detectable reaction product when the fluid sample is added to the first zone, and the liquid reactant is added to the second zone, the fluid sample flows in a first direction from a fluid sample edge to the second zone. zone; the reagent is reconstituted and the liquid forms a liquid reactant containing a liquid reactant capable of reacting with the analyte to form a detectable reaction product and the liquid reactant flows in a second direction opposite to the first direction and into the first zone from a liquid reactant edge. When the flowing fluid sample and the flowing liquid reactant meet, the flow stops, the reactants diffuse into each other and the detectable reaction product is formed by a reaction between the liquid reactant and the analyte at an interface of stable reaction, formed in a joint between the fluid sample and the liquid reactant, and visually distinct from them. In another embodiment, the present invention also provides a device for detecting and quantifying an analyte in a fluid sample that is suspected of containing the analyte, employing a reagent capable of binding the analyte and forming a detectable reaction product from a substrate, relating an amount of the analyte with a quantity of the detectable reaction product The device comprises a fluid transport material capable of absorbing a liquid and causing the capillary flow of the fluid The fluid transporting material has a first zone for the application of the fluid sample which contains the reagent to a first pad to which the same analyte that is being detected and / or quantifying is substantially irreversibly bound, and a second zone for the application of a liquid to a second pad containing a reconstitutable substrate. add the fluid sample containing the reagent to the first pad, the fluid sample containing the reagent that is not bound to the naught, substantially irreversibly attached to the first pad, flows in a first direction from a fluid sample edge to the second zone When the liquid is added to the second pad the substrate in the second pad is reconstituted by the liquid to form a liquid reactant capable of reacting with the reagent, and the liquid reactant flows in a second direction opposite that of the first direction and into the first zone from a liquid reactant edge As a result, when the sample of flowing fluid, which contains the reagent not bound by the analyte in the first pad, the flowing liquid reactant is found, the flow is stopped and the detectable reaction product is formed by a reaction between the liquid reactant and the reagent, and a stable reaction interface is formed in a joint between the fluid sample and the liquid reactant The visually distinct fluid transport material used in the present invention is preferably capable of transporting the fluid sample and the liquid reactant by means of capillary action and thus facilitates the movement of the fluid sample through the material. the fluid transporting material is preferably able to maintain a defined interface with little mixing of the opposing liquids, while allowing the diffusion to occur. In a particular embodiment the fluid transport material comprises a nitrocellulose material fused onto a material pohvinyl or polyester chloride support (ie, Mylar ™) One or more reconstitutable reagents may be contained in the bibulous material in one or more reagent zones Reagents that are to be reconstituted by the fluid sample may be located in the material fluid transport, at a site that is closer to the application site for the fluid sample than from the application site for the diluent solution. Conversely, reagents that are to be reconstituted by the diluting solution may be located in the fluid transport material at a site that is closer to the application site for the diluent solution than the application site for the fluid sample. The flow of fluid through those reagent zones reconstitutes the reagents, effectively pre-treating the sample or mixing and / or reacting one reagent with another. In other embodiments, the reagent or reagents may be contained in an absorbent pad, contacted with the fluid transport material in the liquid reactant zone. The absorbent pad of the group consisting of cellulose, glass fiber, polyester or any absorbent polymer can be selected. An absorbent pad can be placed at the application site of the fluid sample, to pretreat the fluid sample before it enters the absorbent material, for example, to remove red blood cells from a sample containing red blood cells. The reagent or reagents may be present in a plurality of locations on the fluid transport material. In another embodiment, the fluid transport material may be able to separate red blood cells from whole blood, when the fluid sample travels through the bibulous material. In various embodiments, the fluid transport material can be a HEMASEP L® membrane, a HEMASEP V® membrane or a SUPOR® membrane (each obtainable from Pall-Gelman, Port Washington, NY, E. U. A.); a CYTOSEP® membrane (Allstrom Filtration, Mount Holly Springs, PA, E.U.A.), or a nitrocellulose membrane. The amount of analyte present in the sample is determined by measuring the amount of detectable reaction product and determining, from the measured amount of reaction product, the amount of anahto. The detectable reaction product can be measured by any appropriate means known per se. Those skilled in the art For example, if the reaction product absorbs light at a particular wavelength, the absorbance at that wavelength can be measured and related to the amount of anahto. The product can be measured alternatively, when appropriate, the product. of reaction, by transmission, reflection, fluorescence, luminescence or by electrochemical methods, for example, electrical conductance The concentration of unreacted reactants in the fluid transport material can provide a reference value, control or preform for analysis The concentration of unreacted sample in the biblical material also provides a reference value , control or preform for the sample, for example, a sample containing red blood cells can be checked for hemolysis. The device of the present invention can additionally contain a means for calibrating a concentration of the liquid reactant, adding an amount of analyte at an adjacent point a, but other than, the point in the first zone in which the fluid sample is added, so that the analyte and the liquid reactant meet and produce a detectable calibration product. The device of the present invention may additionally consist of a means for simultaneously applying the fluid sample to the first zone and the liquid reactant to the second zone, and an effective sensor for detecting the detectable reaction product. The sensor can be, for example, a CCD image forming camera or an optical image forming device. The present invention also provides a method for detecting and quantifying at least one analyte in a fluid sample that is suspected of containing the analyte, employing a liquid reactant, capable of reacting with the analyte to form a soluble, detectable reaction product. The method includes the steps of providing a fluid transport material having a first zone ("the fluid sample zone") for the application of the fluid sample to a fluid sample application site, and a second zone "the liquid reactant site ") for the application of the liquid reactant at a liquid reactant application site; adding the fluid sample to the first zone and the liquid reactant to the second zone, after which the fluid sample flows in a first direction from a fluid sample edge to the second zone, and the liquid reactant flows in a second direction, opposite to the first direction and to the first zone, from a liquid reactant edge. When the fluid flowing sample and flowing liquid reactant are found, the flow is stopped, the reactants diffuse into each other and the detectable reaction product is formed by reaction between the liquid reactant and the analyte at a stable reaction interface , formed in a joint between the fluid sample and the liquid reactant, and distinct from them. The detectable reaction product is then detected and optionally measured. The detectable reaction product can be detected and can be measured by any appropriate method, such as, for example, absorbance, fluorescence, luminescence, transmission, or electrochemical parameters, such as conductance change. In another embodiment, the present invention provides a method to detect and quantify an analyte in a fluid sample that is suspected of containing the anahto, using a reagent capable of binding to the anahto and forming a detectable reaction product from a substrate, to relate an amount of anahto to a quantity of product of detectable reaction The method cises providing a fluid transport material, capable of absorbing a liquid and causing the capillary flow of the liquid, the fluid transporting material having a first zone for the application of the fluid sample containing the reagent, to a first pad containing the analyte substantially irreversibly bound to the first pad, and a second zone for the application of a liquid to a second pad containing a reconstitutable substrate The fluid sample containing the reagent is added to the first pad and the liquid to the second pad, where the fluid sample subsequently flows into the pad. a first direction from a fluid sample edge to the second zone, and the substrate is reconstituted by the liquid to form a liquid reactant capable of reacting with the reagent, and the liquid reactant flows in a second direction, opposite the first direction and to the first zone, from a liquid reactant edge As a result, when the sample flows to which it flows, which contains the reagent, does not bind to the analyte in the first pad and finds the flowing liquid reactant, the flow is stopped and the detectable reaction product is formed by a reaction between the liquid reactant and the reactant, and a stable reaction interface is formed at a joint between the fluid sample and the liquid reactant, visually distinct from them. The detectable reaction product is subsequently detected and can be further quantified. The reagent can be a plurality of reagents at a plurality of locations. on the fluid transport material The fluid sample may be whole blood, blood plasma, blood serum, urine or any body fluid. In addition, the invention is useful for detecting analytes in a wide variety of materials, such as milk, environmental samples and other samples that contain analytes of interest The reagents can be added to any of the fluid sample and the Diluent solution, or both, before contacting the fluid transport material In this aspect the methods include providing a fluid transport material, as described above, and the bibulous material may contain no reagents or may contain additional reagents, either dry in the fluid transport material, or in a pad that makes contact with the fluid transport material The above objects and other objects, aspects and advantages of the present invention will become apparent from the following description , which should be read in conjunction with the accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an isometric view of the analysis strip of the present invention, showing the locations of the application sites for the fluid sample and the diluting solution; the direction of flow of the diluent solution and the fluid sample, and the location of the reaction product, after the analysis is complete. Figure 2 is an isometric view of another embodiment of the present invention, in which the dry reagent pad containing one or more reagents is affixed to one end of the test strip and the application site of the diluent solution is located in a portion of the dry reagent pad. Figure 3 is a schematic representation of the concentrations of analyte, reagent and reaction product at locations along the bibulous material and illustrates that at the interface the concentration of unreacted analyte and reagents drops abruptly when they react and form the reaction product; and that the concentration of the reaction product rises correspondingly abruptly in the dish. Figures 4A-4F are photographs showing the results, over time, of a glucose analysis carried out with the present invention. Figures 5A-5I are photographs showing the results, over time, of three concentrations of calcium analysis carried out with the present invention. Figure 6 is a graph of color intensity versus time, for six reflection values, read independently , of a reaction interface from a sample having an albumin concentration of 1 2 g / dl, based on the analysis made with the present invention. Figure 7 is a numerical tabulation of color intensity versus time for six values of reflection, read independently, of a reaction interface, and the average value and sample slope having an albumin concentration of 1 2 g / dl, based on an analysis performed with the present invention. Figure 8 is a graph of intensity of color against time for six reflection values independently read, of a reaction interface of a sample having a concentration of albumin of 1 9 g / dl, based on the analysis carried out with the present invention Figure 9 is a numerical tabulation of color intensity versus time for six reflection values, read independently, of a reaction interface, and the value average and the slope of a sample having an albumin concentration of 1 9 g / dl, based on the analysis made with the present invention. Figure 10 is a graph of color intensity versus time for the red reflection values, averaged, of samples having albumin concentrations of 1 2 g / dl and 1 9 g / dl, based on the analysis made with the present invention and read for 15 seconds Figure 11 is a digital color image of an analysis performed with the present invention, of a sample having an albumin concentration of 1 2 g / dl, within 200 msec of interface formation and 2 0 seconds after the sample application, as well as the graph of associated color absorption for a selected portion of the digital color image Figure 12 is a digital color image of an analysis performed with the present invention of a sample having an albumin concentration of 1 2 g / dl in three (3) seconds after the interface formation and five (5) seconds after the application of the sample, as well as the associated color absorption pattern for a selected portion of the digital color image. Figure 13 is an image of digital color of an analysis carried out with the present invention, of a sample having an albumin concentration of 1 9 g / dl within 200 msec of forming the interface and 2 0 seconds after the application of the sample, as well as the associated color absorption chart for a selected portion of the digital color image Figure 14 is a color digital image of an analysis performed with the present invention, a sample that has an albumin concentration of 1 9 g / dl at three (3) seconds after the interface formation and five (5) seconds after the application of the sample, as well as the associated color absorption chart for a selected portion of the digital color image. Figure 15 is a plot of color intensity versus time for three different devices, which read a sample having a glucose concentration of 50. mg / dl, based on an analysis performed with the present invention Figure 16 is a graph of color intensity versus time for three different devices that read a sample having a glucose concentration of 150 mg / dl, based on AN ANALYSIS CARRIED OUT WITH THE PRESENT INVENTION FIG. 17 is a graph of color intensity versus time, for three different devices that read a sample having a glucose concentration of 250 mg / dL, based on an analysis performed with the present Fig. 18 is a graph of color intensity versus time for the average value of samples having a glucose concentration of 50 mg / dl, 150 mg / dl and 250 mg / dl, based on an analysis performed with the present invention and read for 4 5 minutes Figure 19 is a graph of color intensity versus time for samples having calcium concentrations of 9 3 mg / dl and 13 mg / dl, based on an analysis performed with the present invention Figure 20 is a graph of interface amplitude versus time for samples having calcium concentrations of 9.3 mg / dl and 13 mg / dl, with based on an analysis performed with the present invention. Figure 21 is a schematic representation of the various parameters that can be measured in the methods and devices of the present invention. Figure 22 is a representation of the measurement of a portion of the area of the product interface region, as a measurement of the bioactivity in a glucose concentration analysis. Figure 23 is a representation of the internal calibration procedure used in the methods and devices of the present invention, showing the application of the excess analyte near the sample pad in a strip format and the subsequent formation of the analyte point in the reaction product interface. Figure 24 is a digital color image of a glucose analysis demonstrating the internal calibration procedure of the present invention. The calibrated analyte (glucose) was applied at a concentration of more than about 100 mg / dl, and the glucose analysis was carried out according to the method of the present invention. The product in the reaction interface was measured at 20 seconds and 60 seconds after the application of the sample. Figure 25 is a color digital image of an alkaline phosphatase assay, performed according to the method of the present invention, at 15 seconds and 120 seconds after the application of the sample, as well as the associated color absorption graph for a selected portion of the digital color image, at each point of time. Figure 26 is a digital color image of a total bilirubin assay, performed according to the method of the present invention, at a concentration of 4.73 mg / dl of total bilirubin, and measured at 15 seconds and 275 seconds after the application of the sample, as well as the associated color absorption chart, for a selected portion of the digital color image at each point of time. Figure 27 is a digital color image of an analysis for uric acid, carried out according to the method of the present invention, at a concentration of 0.3 mg / dl of uric acid and measured at 5 seconds and 295 seconds after the application of the sample, as well as the associated color absorption chart for a selected portion of the digital color image, at each point of time. Figure 28 is a digital color image of an assay for gamma-glutamyl transferase activity, carried out according to the method of the present invention, at a concentration of 380 U / l of gamma-glutamyltransferase activity, and measured at 15 seconds and 285 seconds after the application of the sample, as well as the associated color absorption chart for a selected portion of the digital color image, at each point of time Figure 29 is a digital image at color of an analysis for the amylase carried out according to the method of the present invention, at a concentration of 16,800 U / l of arnilasa, and measured at 35 seconds and 275 seconds after the application of the sample, as well as the graph of associated color absorption for a selected portion of the digital color image, at each point of time Figure 30 is a digital color image of an analysis for creatine, operated in accordance with the method of the present invention, at a concentration of 150 mg / dL of creatinine, and measured at 5 seconds and 295 seconds after the sample application, as well as the associated color absorption chart, for a selected portion of the digital image the color at each point of time Figure 31 is a color digital image of a test for cholesterol, carried out according to the method of the present invention, at a concentration of 96 mg / dl of cholesterol, and measured at 10 seconds and 300 seconds after the application of the sample, as well as the associated graph of color absorption for a selected portion of the digital color image at each point of time. Figure 32 is a digital color image of an analysis for total protein, operated according to the method of the present invention, at a concentration of 6,200 mg / dl of total protein, and measured at 5 seconds and 295 seconds after the application of the sample, as well as the associated color absorption chart, for a selected portion of the digital color image, at each point of time Figure 33 is a digital image of color absorption of a magnesium analysis, carried out in accordance with the method of the present invention, at a concentration of 4.7 mg / dl of magnesium and measured at 5 seconds and 295 seconds after the application of the sample, as well as the associated UV absorption graph for a selected portion of the absorption image Digital UV at each point of time Figure 34 is a digital color image of an immunoassay for T4, carried out in accordance with the method of the present invention, and measured at 5 minutes after the application of the sample, as well as the graph associated color absorption for a selected portion of the digital color image DETAILED DESCRIPTION OF THE INVENTION The present invention provides devices for detecting anahtos that may be present in a fluid sample, by reacting a liquid reactant with a fluid sample and forming a detectable reaction product. The device of the present invention comprises an absorbent strip made of a fluid transport material ("bibulous material") that is capable of absorbing and transporting the fluid sample, reagents and diluting fluids, by capillary action Analytical reagents capable of being dissolved and distributed within the absorbent strip can be dried in the absorbent strip or in reagent pads in contact with the absorbent strip The device of the present invention is particularly useful for clinical chemistry applications The unexpected result has been observed that two liquids converging from opposite ends of a bibulous material are found in a defined interface with n very accurate, with little mixing of the two opposing solutions for periods of time that reach up to several minutes. This allows the creation of a stable reaction interface, where two opposing liquids containing reagents or analytes, capable of reacting with each other, are find, diffuse and form a detectable product The resulting product is located at the interface for an important period of time, which allows the analysis of the reaction rate and band intensity of the reaction product, without the need to measure the initial volumes of reagents Since the reaction product is visually different from the reagents, high concentrations of reagents can be used. This allows the use of large quantities of certain reagents that can act contrary to endogenous interference compounds, without obscuring the results due to intimately related or densely absorbed spectra d of the unreacted reactants The present invention comprises a significant improvement over the analytical reactive systems available from the prior art, in that the area of detectable reactant is distinct and separated from the unreacted reactants, which allows the use of reaction indicators, which exhibit only minimal changes, as well as extremely high concentrations of reactants. Because the reactants, ie the fluid sample and the liquid reactants, are visually distinct from the reaction product, the system contains a built-in sample of both the unreacted fluid sample as from the unreacted liquid reactant solution These can be used as references for certain types of analytical reactions, such as those involving changes in density and not spectral changes, or those that require a starting reagent or a reference value The devices of the present invention can be It is made of any material that is capable of absorbing liquids and causing capillary flow from high concentration areas to areas of low concentration of the device, while maintaining a defined reaction product interface, with little mixing of the opposing liquids. The devices can be made of nitrocellulose membranes, cellulose sheets, porous pohetylene, polyethersulfone or membranes of a variety of other materials. Porous plastics of a variety of polymers can also be used, such as polyethylene, polystyrene or polypropylene. Materials are much preferable. bibulous made of nitrocellulose, molded on a support material, such as PVC or Mylar ™ (or other polyester film) An example of this type of bibulous material is available from Schleicher and Schuell, Catalog No. FF-170 When using nitrocellulose , the nitrocellulose materials must be previously treated first to make the hydr Oils the membranes The fluid transport material can be adhered to a solid support, such as PVC or polystyrene, in order to give durability in handling These materials are given by way of example and are not intended to be a limitation. The person having ordinary skill in the art will realize that a variety of materials in the present invention, as long as the material has the properties of being able to absorb the sample, support a capillary action and, thereby, facilitate the movement of the fluid sample through the material, and maintain a defined interface, with little mixing of the opposing liquids With respect to the hydrophilic absorbent materials, two factors affect the utility in the present invention First, the pore size affects the integrity of the reaction interface As the pore size increases the interface of the pore diffuses. reaction and becomes more diffuse Second, as the percentage of solids (in volume / volume) in the membrane increases, the The signal size of the reaction interface decreases, presumably due to the smaller volume of the reaction liquid at the interface. It is preferable that the pore size be of the order of 5 μm based on currently available materials. It is conceivable that a small material Pore size and low solids content can be an excellent material In the preferred embodiments for analyzing samples containing whole blood or blood products containing undesirable red blood cells, the fluid transport material can be a material that separates the plasma or the blood product of red blood cells In those embodiments, the fluid transport material can be a HEMOSEP V® or HEMOSEP L® membrane (obtainable from Pall-Gelman Ine, Port Washington, NY, USA), or a CYTOSEP® membrane ( obtainable from Allstrom Filtration, Mount Holly Sppngs, PA, USA) The methods and devices of the present invention allow the preparation and One-step sample analysis in the same device The device can be a strip in the form of a generally rectangular shape Alternatively the bibulous material can also be a circular or linear grouping or a star-shaped configuration, which has the additional advantage of allowing that can analyze multiple anahtos in a single analysis Of course, who has ordinary experience in the matter will realize that the bibulous material can be in any way, advantageous under particular circumstances The present invention can employ reactive systems capable of carrying out chemical evaluation of analytes that are commonly present in biological fluids. Such reactive systems are widely known in the art. Those of particular interest are those reactive systems that utilize a single component, that is, when the reaction occurs in a single solution rather than those that require more than an incubation step s incoherent The present invention provides single component reactive systems, composed of several different chemical reagents, where the reagents are dried in spatially separated zones in the strips. As shown in Figures 1 and 2, the dry reagent strips of the present invention can be used by applying a diluent solution ("diluent solution" is defined as any liquid capable of dissolving a reagent.) Any reagents that are added to the solution diluent or reconstituted by the diluent solution, are intended to be included in the definition as part of the diluent solution), at one end of the strip and a fluid sample ("fluid sample" or "fluid sample" is defined as any fluid which contains an analyte to be analyzed.Any reagents that are added to the fluid sample or reconstituted by the fluid sample, are intended to be included in the definition, as part of the fluid sample) that is to be analyzed to the extreme gold . Referring to figure 1 the fluid sample can be applied to the fluid sample application site 1 in the fluid sample zone ("fluid sample zone" is defined as any area in the bibulous material that is closer to the sample application site than to the site liquid reactant application) and the liquid reactant can be applied to site 2 of liquid reactant application in the liquid reactant zone ("liquid reactant zone" is defined as any area in the bibulous material that is closest to the liquid reactant site). application of liquid reactant to the application site of the fluid sample) When the two liquids move towards each other through the strips the sample can be separated to the components For example, when using cell separator strips, the fluid sample can be separated to plasma and red blood cells. The fluid sample can also reconstitute one or more reagents as it moves through the fluid transport material, thus pretreating the sample before final reactions occur The liquid reagent moves simultaneously from the opposite end of the strip and can optionally dissolve in sequence one or more dry reagents that may be present in the liquid reagent zone of the strip When the fluid sample and the reactant are found liquid, a reaction interface is formed between the transport liquids The reaction products occupy a very narrow band at the interface and are measured in terms of speed and intensity of the formation Usually the increase in the amount of formed product will be measured (or of decrease in the amount of reagent and / or analyte supplied), as a function of time Alternati The quantity of the product, the reagent and / or the analyte can be measured at one or more fixed time points. The change in the amount of product formed is typically measured by measuring the increase or decrease in absorbency over time, at a length of wave at which the maximum absorbance is detected In a preferred embodiment the reaction products will be measured using reflection However, one of ordinary skill in the art will realize that other means of measuring the reaction products, such as by the use of electrochemical methods (e.g., measuring conductance changes), fluorescence, luminescence, transmission or other methods known in the art, which provide a detectable signal related to the presence and / or amount of a reaction product. The resulting reactant band is stable for a few minutes, with little product diffusion to the surrounding area, which allows Time for determining the speed and intensity of color development Figure 2 illustrates another embodiment of the invention, where one or more reagents that may be present in the bibulous material may be present in the form of a reagent pad 3 dry In this embodiment, the dry reagent pad 3 is located in a portion of the diluent solution application site 2 The fluid sample application site may additionally contain one or more pads to process the fluid sample before exposing it to the reagent As an example, the application site of the fluid sample may contain a blood sample processing pad, for pretreatment of whole blood samples or samples containing whole blood. Examples of those pads include Hemasep-L or, more preferably, Hemasep-V (Pall Corporation) or fiberglass Additionally the reagent application site can inc Also, add a pad containing a dry reagent, capable of being reconstituted by the addition of a diluent. This replaces the need to apply a liquid reagent with the rather simple reconstitution of a dry reagent, using a diluent. In some cases it may be preferable to measure the disappearance of a reagent or anahto, instead of the appearance of a product For example, a reduced nicotinamide-adenine dinucleotide (NADH), a cofactor for many enzymes, absorbs light much more strongly at 340 nm than when in oxidized form, NAD Consequently, when measuring the activity of an enzyme using NADH as a cofactor it may be advantageous to measure the absorbance reduction at 340 nm Alternatively the formation of NADH can be measured as an increase in absorbance at 340 nm Figure 3 is an illustration graph that shows hypothetical relative concentrations of ana to be analyzed, reaction product and reactant in the locations ions along the bibulous material The relative concentrations illustrated can be typical of those found in the bibulous material during the analysis Figure 3 is illustrative of four types of analysis that can occur in the bibulous material Line 70 represents the product formed The lines 50 and 60 mean "anahto consumed" and "reactive consumed", respectively, and can illustrate a reaction where the reagent or anahto is consumed, such as a dye binding analysis, where the dye is bound to an analyte and both the dye and the anahto are "consumed" in the complex, when the reaction occurs. At the reaction interface the concentrations of unconsumed analyte and unconsumed reactant drop abruptly as the concentration of the reaction product rises abruptly. In other types of reactions the reagent is not consumed in the reaction. For example, in enzymatic assays, the enzyme is not consumed, but simply converts an analyte (or substrate) to a detectable product. In this case the unconsumed reagent is represented by line 80 and the analyte consumed by line 50. In another type of analysis the reagent can be consumed and the analyte can not be consumed, as for a serum enzyme (represented by line 90). ). There are four types of analysis that can occur that are illustrated by Figure 3; those in which the analyte is consumed and the reagent is not consumed; those where the analyte is not consumed and the reagent is consumed; and those in which both analyte and reagent are consumed or not consumed. Because the reaction interface remains visually distinct from the fluid sample and the reagent solution in the bibulous material, the device incorporates a built-in methodology to determine both the concentrations and dilutions of the fluid sample. When the dry reagents are reconstituted, the device also provides the internal calculation of the reference values that take into account the degree of dilution of the reagents in the diluent solution and in the fluid sample (that is, they reflect the degree to which the dry reagents that may be present have been dissolved in the diluting solution or in the fluid sample), and for the measurement of the background signal, all of which may be useful in certain types of analytical chemistry formats. For example, certain fluid samples they may contain material that reflects light at a wavelength at or close to that of the reaction product and, therefore, this signal must be subtracted from the final color intensity of the reaction product. In other formats, for example, when the results are directly related to the concentration of reagent, for example, in speed reactions, where the anahtos are in excess, a simultaneous measurement of the concentration Initial reagent and product concentration, by the intensity of light reflected at different wavelengths, allows the adjustment of the resulting analyte concentration values, based on the variability in the degree of reagent dissolution. Ordinary experience in this technique will recognize that the method of the present invention allows the measurement of numerous other parameters that may be useful in measurements of operational stability, as well as calibration or calculation of background or reference values. said parameters include, without limitation 1, the distance between an edge of the sample application site and the reaction interface, and the change of distance with time (A in Figure 21); 2. the distance between one edge of the reagent application site and the reaction interface, and the change in distance with time (B in Figure 21); 3. the distance between a border of the sample application site and the liquid interface, and the change in distance with time (C in Figure 21); 4. the distance between one edge of the reagent application site and the liquid interface, and the change in distance over time (D in Figure 21); 5. the distance between the reaction interface and the liquid interface, and the speed of the change in distance with time (E in Figure 21); 6. the area of the liquid interface (I in Figure 21); 7. the absorbance or reflectance of the sample bottom (J in Figure 21); 8. the absorbance or reflectance of the reagent bottom (K in Figure 21); and 9. the absorbance or reflectance of the liquid interface and the rate of change in that same parameter with time (L in Figure 21). Clinical chemistry analyzes, whether they are liquid based or solid based, can be read by kinetic analyzes (product formation speed: G in Figure 21) or end point analysis (production amount in one or more points given in time, F in Figure 21). It is preferred that the detectable reaction product is measured by determining the rate of product formation (G in Figure 21). With respect to solid-based clinical chemistry analyzes, the present invention offers the only way to measure velocity from a true zero time point, since the reaction start time can be viewed and controlled within milliseconds. This allows to measure the speeds within the first few seconds of the analysis, which is unique and useful. Additionally, the amplitude of the reaction interface band can be measured, which can be correlated with the analyte concentration. Finally, a whole portion of the area of the interface band within a region of interest can be measured as a determination of the total product formation (H in Figure 21, Figure 22). These parameters can be followed in time or the same region can be compared between different samples to give a relative measure of product development and, thus, the concentration of the analyte. The desired parameter can be measured using any appropriate image forming device. Especially preferred are the image-forming devices that allow the quantification of the measured parameter, for example, by converting the measured values for the parameter into data suitable for processing by a computer. Examples of such devices include three-color CCD image forming chambers, or three-capsule image formers that can employ optical elements and a rotating filter wheel. In another embodiment, a component that does not interfere on the sample side can be dried. fluid of the bibulous material, and it can be analyzed at various points along the bibulous material as it dissolves at the front of the advancing sample fluid, to determine the presence of the sample at the interface. For example, a dye with a spectrum Absorption other than the product can be dried on the fluid sample side of the pad. Measurement of that dye on the fluid sample side of the reaction interface can be performed to determine the presence of the fluid sample at the reaction site In another embodiment, an amount of the anahto that is to be detected and / or measured can be dried at a point on the bibulous material that is between the fluid sample application unit and the liquid reagent application site The analyte is reconstituted with a diluent and the liquid reagent and the analyte flow towards each other, as described above. The liquid reagent and the analyte are and form a detectable calibration product The calculation of the quantity of the reaction product is assisted by a determination of the amount of reagent present in the reaction interface which may be a function of the amount of the detectable carbon product. The methods of the present invention aimed at measuring the concentration of an anatous, there is a large excess of reagent with respect to the anahto However, to calibrate the amount of reagent in the reaction interface, the situation is reversed to produce an excess of anahto with respect to the reagent, by putting a relatively large amount of anahto in the bibulous material, in a position on the line with, but different from, the sample application site. Fluid (Figure 23) The anatole can be applied in the form of a single high-concentration point, but is preferably applied as an anahto fringe or slot (Figure 23), since this allows the application of the same amount of anahto at a lower concentration, avoiding the possibility of problems associated with high anahto concentrations, such as precipitation or crystallization of the anahto The anahto thus applied migrates with the sample to the reagent application site and forms a large product point at the interface of reaction (Figure 24) This point can be measured in the same way as the reaction product that is produced by the anate sample. Deviations from the values are The measurement of the calibration point can indicate the occurrence of any of several cases that may influence the concentration of the reagent, such as, for example, degradation of the reagent, difficulties in the reagent supply, lack of reagent dissolution , precipitation of the reagent and the like The calibration method described above can also be used as a positive control method to confirm the activity of the analysis when a negative result is frequently expected. In this embodiment a small amount of the anatole is applied to the bibulous material and migrates to the reagent application site The formation of a calibration product detectable in the calibration interface gives evidence that the analysis is working properly, and that any negative result is due to the absence of anahto in the liquid sample operated simultaneously. following is an exemplary list, not exclusive, of s analytes that can be identified with the present invention alanine-amido-transferase (ALT) (enzyme substrate), albumin (dye binding), alkaline phosphatase (enzyme substrate), ammonia (enzymatic) amylase (enzyme substrate), aspartate-amino -transferase (AST) (enzyme substrate), total bihrubin (dye binding), calcium (dye binding), cholesterol (total) (enzymatic), creatine kinase (CK) (enzyme substrate), creatinine (dye binding), 2 -glutam? transferase (GGT) (enzyme substrate), glucose (enzymatic) lactate dehydrogenase (enzyme substrate), raisin (enzymatic substrate), magnesium (dye binding), phosphorus (dye binding), protein (total (binding of dye), t glyceride (enzymatic), urea nitrogen (BUN) (enzymatic) and uric acid (enzymatic) The types of reaction, enzyme substrate, dye and enzyme linkages, referred to above, can result in Chromogenic reaction and / or ult raviolet, to identify the anahtos of the above list The present invention can also employ, instead of the liquid reagent that is capable of reacting with the anate, a reagent that is capable of binding to the analyte. The reagent can be any molecule that is capable of of binding to an anabolic of interest, such as an antibody, a receptor, a receptor body, an antibody fragment, an abtida or the like The reagent additionally contains (i.e., is conjugated with or linked to) an enzyme or a fragment of enzyme that produces a detectable reaction product, when the reagent is incubated with an appropriate substrate. There are numerous known methods for detecting the binding of an anahto to said reagent. In one embodiment, illustrated herein in Figure 34, a defined amount of the reagent is mixed. with the liquid sample suspected of containing the analyte of interest When mixed, the reagent binds to any analyte present in the liquid sample, forming or a strongly associated complex between the anahto and the reagent Then the mixture is applied to a pad located at one end of the bibulous fluid transporting material The pad contains a defined amount of anahto, which is substantially irreversibly bound to the material constituting the pad. By being attached or linked in a substantially irreversible manner it is meant that during the course of the analysis time no detectable amount of the anahto dissociates from the pad. The reagent not bound in the sample The liquid in the liquid sample that has been previously bound to the liquid present in the liquid sample, does not bind to the analyte that is in the pad. the shape of a reactive / analyte complex is then moved through the fluid transport material. At the same time, a substrate present at the other end of the bibulous fluid transport material is flowed to the liquid sample. At the point where the substrate and the liquid sample are located, a reaction product is formed which is detectable by the action of the enzymatic portion of the reagent with the substrate. As before, the resulting product is located at the reaction interface for a significant time, which allows the reaction rate and the intensity of the reaction product to be easily analyzed. The reaction rate and / or the concentration of the product can be related to the concentration or amount of analyte present in the liquid sample by any appropriate means, such as the use of a calibration reaction or a standard curve. The reagent can be any molecule that is capable of binding to the analyte of interest. Said molecules can be a monoclonal antibody or a portion thereof; a receptor protein or a portion of it, or an abtida or a portion of it. Examples of known antibody binding portions include, without limitation: an F (ab) fragment, an F (ab ') fragment, an F (ab') 2 fragment, an Fv fragment, an scFv fragment and the like . An example of a receptor portion that can be used in the present invention is a receiving body. The methods for generating said antibody-binding portions and receptors and for use in binding reactions are well known to those skilled in the art. The reagent, in any form, must be capable of specifically binding to the present interest of interest. in the liquid sample, at a sufficient affinity for the complex to pass through the pad located at one end of the bibulous fluid transport material, without dissociation of a significant portion of the complex. If said dissociation occurs, then the reagent could bind to the pad fixed to the pad and will not pass through the pad to react with the substrate in the bibulous fluid transport material The amount of reagent added to the liquid sample should be within a scale dictated by the amount of present on the pad and for the anticipated amount of water in the liquid sample. The amount must be at least If the amount of reagent added is less than the amount of anahto present in the sample, the reported result will be less than the true concentration of anahto in the liquid sample. , the amount of reagent added to the liquid sample should not be greater than the amount of anahto bound to the pad. If the amount of reagent added to the liquid sample is greater than the amount of analyte present in the pad, then the reported result will be greater than the true anahto concentration in the liquid sample. Additionally, the amount of air in the pad must be much greater than the amount of analyte expected to be present in the liquid sample. If the amount of anahto present in the pad is insufficient to bind the unbound reagent present in the liquid sample, then the reported result will again be greater than the true concentration of analyte in the liquid sample. The reagent is linked to an enzyme that can react with the substrate that migrates from the other end of the fluid transporting material. The reagent and the enzyme can be linked together by means generally known to those skilled in the art, such as covalent linkage, disulfide bridge and the like, and are commercially available from a variety of suppliers (eg, Sigma Chemical Co. ., St. Louis, MO, E, AU). The substrate and the enzyme pair with each other, so that the enzyme acts on the substrate to produce a detectable reaction product. Examples of such enzymes include: alkaline phosphatase, beta-galactosidase and peroxidase. For alkaline phosphatase acceptable substrates may be, without limitation: p-nitrophenol phosphate, 4-methylumbelliferyl phosphate or BCIP / NBT (5-bromo-4-chloro-indolyl phosphate / nitroblue tetrazolium). The alkaline phosphatase acts on the p-nitrophenol phosphate substrate to produce the detectable reaction product p-nitrophenol. The alkaline phosphatase acts on the 4-methylumbelliferyl phosphate to produce the fluorescent product methylumbelliferone. For beta-galactosidase, acceptable substrates may include, without limitation, o-nitrophenyl-beta-D-galactoside or 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside ("X-gal"). The substrate o-nitrophenyl-beta-D-galactoside is divided by beta-galactosidase to form D-galactoside and the detectable reaction product o.nitrophenol. For peroxidase, acceptable substrates include: 3-amino-9-ethylcarbazole ("AEC"), o-phenylenediamine dihydrochloride ("OPD"), 4-chloro-1-naphthol; 3,3'-diaminobenzidine tetrachlorohydrate ("DAB") and the like. The substrate concentrations required to produce acceptable levels of detectable product for use in the present invention can be altered as required for the selected sample, analysis and conditions, and as determined by those skilled in the art. Other substrates for these enzymes are widely known to those skilled in the art and can be substituted, as appropriate. Additionally other enzyme / substrate pairs known to those skilled in the art can also be employed in the methods and devices of the present invention, as appropriate. The following examples illustrate the use of the present invention to detect and quantify particular components in a fluid sample. These examples are provided for illustration, and are not intended to be limiting. Those skilled in the art will realize that illustrated principles and techniques can be applied to detect a variety of analytes in a variety of fluid samples.

EXAMPLE 1 This example illustrates how a device of the present invention was used to determine the presence and concentration (246 mg / dl) of glucose in a whole blood sample. A HEMOSEP L® membrane was attached to an adhesive plastic backing and cut to 4 x 25 mm strips 15 μg of Tpnder reagent (Sigma Chemical Co., St. Louis, MO, USA) containing 15,000 u / L) of glucose oxidase, 0 5 mM of 4-aminanthant was dried. pna, 20 mM of p-hydroxybenzene sulfonate and 10,000 u / L of peroxidase, at a pH of approximately 7.0, on one end of each test strip, which comprised approximately half of the total area of the strip. This was achieved by supplying simultaneously 10 μl of water to one end of the strip (the fluid sample side) and 10 μl of Tpnder reagent (at 5x concentration) to the other end of the strip (the diluent solution side) Then the strip is air dried for one hour at room temperature After drying 15 μl of water was added to the extremity or outside the diluent solution side of the strip, at the diluent solution application site, and 15 μl of whole blood was simultaneously added to the outer end of the fluid sample side of the strip, at the fluid sample application site. two liquids flowed towards each other, eventually producing four distinct bands in the strip a band of red blood cells, a band of plasma, a band of reaction product of the red / brown quinonaimine dye (the reaction interface) and a band of unreacted Tpnder reagent As shown in Figures 4A-4F, the product interface band colored with the quinonaimine dye continued to develop for a few minutes, its rate of development and its final color intensity being proportional to the initial glucose concentration in the sample EXAMPLE 2 This example illustrates how the present invention was applied to detect and quantify calcium in fetal calf serum. Three polyether sulfone membranes were prepared as described in Example 1 and washed with 50 μl of HCl diluted to pH 2. An example of a pohetersulfone membrane suitable for use in the present invention is a SUPOR® membrane (Pall-Gelman, Port Washington, NY, USA). Whoever has ordinary skill in the art will realize that other porous membranes with similar characteristics can also be applied to the present invention 15 micro-hours of fetal calf serum containing 6 8, 13 and 186 mg / dl of calcium was added, beside fluid sample of each strip, in the fluid sample application site, while simultaneously adding 15 μl of red acid / purple dye solution Arsenazo III acidified (Sigma Chemical Co, St Louis, MO, USA, catalog No 588, prepared according to the instructions from the manufacturer) to the diluent solution side of the strip, at the application site of the diluting solution. In each case the two liquids flowed towards each other and when they formed they formed a discrete interface. The blue reaction product, calcium-arsanazo III, was developed in the product interface. As shown in Figures 5A-5I, both the time for color development and the final intensity of the blue color were proportional to the initial calcium concentration in the fluid samples.

EXAMPLE 3 In this example, concentrations of 1.2 g / dl and 1.9 g / dl of albumin in fetal calf serum were tested, with the present invention, using bromocresol green dye after adjusting the pH to 5.5. A HEMOSEP L® membrane was attached to an adhesive plastic backing and cut into 4 x 25 mm strips. BCG reagent (15 μl; Sigma Chemical Co., St. Louis, MO; Catalog No. 631, prepared according to the manufacturer's instructions, except that a 10x concentrated solution of the reagent) was used at one end of each test strip, which comprised approximately half the total area of the strip. 15 μl of serum was simultaneously added to the other end of the diluted sample side of the strip, in the fluid sample application site. The two liquids flowed towards each other, eventually producing three distinct bands on the strip: a serum band, a band of reaction product (the reaction interface), which includes a dye / albumin complex, and a reagent band BCG without reacting Figures 5, 7 and 10 are graphical representations and figures 5 and 9 are numerical representations of the color intensity of the reaction product against time, both for the 1.2 g / dl sample and 1.9 g / dl. These graphs show that the analysis carried out according to the present invention produces a substantial color intensity within five (5) minutes from the application of the sample to the test strip of the present invention, which is proportional to the concentration original analyte, based on the slope and final color intensity. Figures 11 to 14 are digital photographs of test strips of 1.2 g / dl and 1.9 g / dl at 200 mih seconds (2.0 seconds after sample application to the test strip) and 3.0 seconds after training interface (5.0 seconds after the sample application to the test strip). These digital images were recorded with a Sony Progressive 3CCD camera and the digital data was uploaded to a Gateway PC, where a selected row of pixels of the images was analyzed, using Matrox's INSPECTOR color absorption application program. Comparing figure 11 with figure 12, for the sample of 1.2 g / dl, and figure 13 with figure 14 for the sample of 1.9 g / dl, there is a large increase in the absorption of red (green color) occurred in less than three (3) seconds, as shown by line "R" of figures 11 to 14, which represents the increase in red absorption (greater green color) through the reaction interface. In general, throughout this application, an increase in absorption to a given color is reflected as a downward deflection in the color graph.? Thus, the analysis protocol of the present invention produces a determinable reaction at a reaction rate such that the analysis can be carried out in five (5) seconds from the addition of the sample, and in three (3) seconds after the Interface formation.

EXAMPLE 4 This is another example using the protocol of Example 1 and illustrating how a device of the present invention was used to determine the presence and concentration of glucose in a whole blood sample. In this example, samples of 50 mg / dl, 150 mg / dl and 250 mg / dl were used. A HEMOSEP L® membrane was attached to an adhesive plastic backing and cut into 4 mm x 25 mm strips. 15 μl of Trinder reagent (Sigma Chemical Co., St. Louis, MO, USA, catalog No. 315, prepared according to the manufacturer's instructions, except that a reagent solution at 5x concentration was used) was added, contained glucose oxidase (15,000 u / L), 0.5 mM of 4-aminoantipyrine, 20 mM of p.hydroxybenzene sulfonate and 10,000 u / L of peroxidase, at a pH of approximately 7.0, at one end of the test strip, which comprises approximately half of the total area of the strip. 15 μl of serum was simultaneously added to the outer end of the fluid sample side of the strip, at the application site of the fluid sample. The two liquids flowed towards each other, eventually producing three distinct bands on the strip: a band of serum, a band of red / brown dye reaction product of quinonaimine (the reaction interface) and a band of unreacted Tpnder reagent Figures 15 to 18 show the rate of development of the quinoneimine dye product. These graphs show that the analysis performed in accordance with the present invention produces a substantial color intensity within 2 to 4 minutes from the application of the sample. to the test strip of the present invention EXAMPLE 5 This is another example using the protocol of Example 2 and illustrating how the present invention was applied to detect and quantify calcium in fetal calf serum. In this example samples of 9 3 mg / dl and 13 mg / dl Polyethersulfone membranes were prepared as described in Example 1 and washed with 50 μl of HCl diluted to pH 2 0 Fifteen micro-hours of fetal calf serum containing 9 3 mg / dl and 13 mg / dl of calcium were added, next to the fluid sample of each strip, at the fluid sample application site, while simultaneously adding 15 μl of acidified red / purple Arsenazo III acid solution, to the solvent solution side of the strip, at the application site of diluent solution In each case, the two liquids flowed towards each other and when they met, they formed a discrete interface The blue, calcium-Arsenazo III reaction product was developed in the interface Referring to figures 10 and 20 ,. showing graphical and numerical representations of this example, Figure 19 shows that the analysis performed in accordance with the present invention produces a substantial color intensity within one minute from the application of the sample to the test strip of the present invention. Figure 20 shows the relative stability of the interface width with time. The interface width doubles approximately 100 seconds to 250+ seconds.

EXAMPLE 6 This example illustrates how the present invention was applied to detect and quantify total alkaline phosphatase in fetal calf serum. In this example, serial dilutions of alkaline phosphatase were used on a scale of 10 times the concentration. Nitrocellulose membrane strips were washed with NaOH diluted to pH 10. 15 microliters of fetal calf serum containing various dilutions of alkaline phosphatase was applied to sample side of the membrane strip at the fluid sample application site, while simultaneously added 15 μl of alkaline phosphatase reagent (Sigma, Catalog No. 245, prepared in accordance with the manufacturer's instructions, except that a 2x concentrated reagent solution was used, next to the strip's diluent solution, at the application site of the diluting solution. The reaction product, p-nitrophenol, was developed in the product interface. Figure 25 is a digital photograph of one of the test strips, showing the product formation at 15 seconds and at 120 seconds after the application of the sample to the test strip. These digital images were recorded as described for the example Figure 25 shows that the analysis carried out in accordance with the present invention produces a detectable color intensity within 15 seconds from the application of the sample to the test strip of the present invention, and a substantial color intensity in 120 seconds EXAMPLE 7 This example shows how the present invention was applied to detect and quantify total biurubin in fetal calf serum. In this example, samples of 0 65 mg / dl, 2 55 mg / dl, 4 73 mg / dl, 9 were used. 39 mg / dl and 19 57 mg / dl Pohetersulfone membranes were prepared as described in Example 1 and washed with water at pH 7 0 15 micrograms of a commercial standard solution, containing 065 mg / dl, was added. 2 55 mg / dl, 4 73 mg / dl, 9 39 mg / dl or 19 57 mg / dl of bihrubin, next to fluid sample of each strip, at the fluid sample application site, while adding 15 μl simultaneously of total bihrrubin reagent (Sigma, Catalog No. 550-4, reconstituted with sodium nitrite, according to the manufacturer's instructions, except that a reagent solution at a concentration of 20x was used), along with diluent solution of the strip, in the application site of the diluent solution In each case the two liquids flowed towards each other and, found, they formed a discrete interface The reaction product, azobilirubin, was developed in the product interface Figure 26 is a digital photograph of the 4 73 mg / dl Figure 26 shows the product formation at 15 seconds and 275 seconds after the application of the sample to the test strip. These digital images were recorded as described for Example 3, Figure 26 shows that the analysis carried out in accordance with the present invention produces a substantial color intensity within 15 seconds from the application of the sample to the test strip of the present invention EXAMPLE 8 This example illustrates how the present invention was applied to detect and quantify uric acid in fetal calf serum. In this example, samples ranging from 0 15 mg / dl to 15 5 mg / dl were used. Poetersulfone membranes were prepared as described in Example 1 and washed with water at pH 7 0 Fifteen microliters of fetal calf serum containing 0 15 mg / dl, 0 3 mg / dl, 0 6 mg / dl, 10 mg / dl was added. mg / dl, 7 3 mg / dl and 15 5 mg / dl of uric acid next to fluid sample of each strip at the fluid sample application site, while simultaneously adding 15 μl of uric acid reagent (Sigma No of catalog 685, except that a concentrated solution of 3 3x reagent was used next to diluent solution of the strip, at the site of application of diluting solution. In each case the two liquids flowed towards each other and, when found, formed a discrete interface. The reaction product, a quinonaimine dye that had a maximum absorption at 520 nm, was developed at the product interface. Figure 27 is a digital photograph of the 0.3 mg / dl test strip showing the product formation within 5 seconds and 295 seconds after the application of the sample to the test strip. These digital images were recorded as described in Example 3 and show a substantial product intensity, developed after 295 seconds.

EXAMPLE 9 This example illustrates how the present invention was applied to detect and quantify gamma-glutamyltransferase in fetal calf serum. In this example, samples ranging from 8 units / liter (u / L) to 725 u / L were used. Nitrocellulose membranes were washed with water at pH 7.0. 15 microliters of fetal calf serum containing 8, 37, 107, 380 and 725 u / L of gamma-glutamyltransferase was added to the fluid sample application site, while 15 μl of gamma-glutamyltransferase reagent was added simultaneously (Sigma , Catalog No. 419, prepared according to the manufacturer's instructions, except that a concentrated reagent solution was used at 2x) next to the strip's diluting solution, at the application site of the diluting solution. In each case the two liquids flowed towards each other and when they formed they formed a discrete interface The reaction product, 5-amin-2-n-trobenzoate, which has a maximum absorption at 405 nm, was developed in the product interface Figure 28 is a digital photograph of the 380 u / L test strip showing the product formation at 5 seconds and 285 seconds after the application of the sample to the test strip. These images were recorded as described in Example 3 and show a substantial product development occurred after 295 seconds This example illustrates how the present invention was applied to detect and quantify gamma-glutamyltransferase in fetal calf serum. In this example it was used samples that vary between samples of 8 units / liter (u / L) and 725 u / L Nitrile cellulose membranes were washed with water at pH 7 0 15 microherres of fetal calf serum containing 8, 37, 107, 380 and 725 u / L of gamma-glutamyltransferase to the sample application site, while simultaneously adding 15 μl of gamma-glutamyltransferase reagent (Sigma Catalog No. 419, prepared according to the manufacturer's instructions , except that a reagent solution at 2x concentration was used, next to the diluent solution of the strip, at the application site of the diluting solution. In each case, the two liquids flowed towards each other and when they formed a discrete interface The product of the reaction, 5-amin-2-n-trobenzoate, which has a maximum absorption at 405 nm, was developed in the product interface Figure 28 is a digital photograph of the 380 u / test strip L, which shows the product formation 5 seconds and 285 seconds after the application of the sample to the test strip. Those digital images were recorded as described for Example 3, and show that substantial product development occurred after 285 seconds.

EXAMPLE 10 This example illustrates how the present invention was applied to detect and quantify amylase in fetal calf serum. In this example, samples were used that varied between samples of 88 units / liter (u / L) and 16,800 u / L. Nitrocellulose membranes were washed with water at pH 7.0. 15 micro-hours of fetal calf serum containing 88, 362, 1680 and 16800 u / L of amylase was added to the fluid sample application site, while 15 μl of amylase reagent was added simultaneously (Sigma, Catalog No. 419, prepared in accordance with the manufacturer's instructions, except that a concentrated solution of 2x reagent was used next to diluent solution of the strip at the application site of the diluting solution. In each case the two liquids flowed towards each other and, when found, formed a discrete interface. The reaction product p-nitrophenol having a maximum absorption at 405 nm was developed at the product interface. Figure 29 is a digital photograph of the test strip at 16,800 u / L showing the product formation 35 seconds and 275 seconds after the application of the sample to the test strip. These digital images were recorded as described in Example 3. An important level of product development occurred after 275 seconds.

EXAMPLE 11 This example illustrates how the present invention was applied to detect and quantify creatinine in fetal calf serum. In this example, samples varying between 75 mg / dl and 300 mg / dl were used. Nitrocellulose membranes were washed with water at pH 7.0. 15 micro-hours of fetal calf serum containing 75 mg / dl, 150 mg / dl and 300 mg / dl of creatinine was added to the fluid sample application site, while simultaneously adding 15 μl of creatinine reagent (Sigma, No. catalog 557-A and 557-B, prepared according to the manufacturer's instructions, except that a 2x concentrated reagent solution was used) next to the diluent solution of the strip at the application site of the diluting solution. In each case the two liquids flowed towards each other and, when found, formed a discrete interface. The reaction product, a Janovski complex, which has a maximum absorption between 480 and 520 nm, was developed at the interface. Figure 30 is a digital photograph of the 150 rng / dl test strip showing the product formation 5 seconds and 295 seconds after the application of the sample to the test strip. These digital images were recorded as described for Example 3 and show a significant level of the product formed after 295 seconds EXAMPLE 12 This example illustrates how the present invention was applied to detect and quantify cholesterol. In this example, samples varying between 61 m / dl and 183 mg / dl were used. Nitrocellulose membranes were washed with water at pH 7 0 15 micro-hours of a normal commercial cholesterol solution containing 61 mg / dl, 96 mg / dl, 160 mg / dl or 183 mg / dl of cholesterol was added to the application site of fluid sample, while simultaneously adding 15 μl of cholesterol reagent (Sigma, Catalog No. 352) to the diluent solution of the strip at the application site of the diluting solution In each case the two liquids flowed towards each other and at the same time were formed a discrete interface A reaction product, a quinonaimine dye that has maximum absorption at 500 nm, was developed in the product interface. Figure 31 is a digital photograph of the 96 mg / dl test strip, showing the product formation 10 seconds and 300 seconds after applying the sample to the test strip These digital images were recorded as described for example 3 A detectable level of product was formed in the term 10 seconds after the application of the sample to the test strip, and had an increase substantially after 300 seconds EXAMPLE 13 This example shows how the present invention was applied to detect and quantify total protein In this example samples were used ranging from 2 1 g / dl to 8 3 g / dl Washed with water nitrocellulose membranes at pH 7 0 was added 15 micro-hours of fetal calf serum or dog, containing 2 1 g / dl, 4 1 g / dl, 62 g / dl and 82 g / dl of total protein, to the application site of the fluid sample, while simultaneously adding 15 μl of alkaline biuret reagent (Sigma , Catalog No. 541), prepared in accordance with the manufacturer's instructions, except that a concentrated reagent solution was used at 15x) next to the strip's diluting solution, at the diluent solution application site. liquids flowed towards each other and as they formed a discrete interface The reaction product, a purple copper-protein complex that had a maximum absorption at 540 nm, was developed in the product interface Figure 32 is a digital photograph of the test strip of 6 2 g / dl, which shows the product formation 5 seconds and 295 seconds after the sample application to the test strip These digital images were recorded as described for example 3 A level was detectable The important product after 5 seconds and a substantial amount of product formed after 295 seconds EXAMPLE 14 This example illustrates how the present invention was applied to detect and quantify magnesium in fetal calf serum. In this example, a sample containing 4.7 mg / dl of magnesium was used. Nitrocellulose membranes were washed with NaOH diluted to pH 10.0. 15 microliters of fetal calf serum containing 4.7 mg / dl of magnesium was added to the fluid sample application site, while simultaneously adding 15 μl of magnesium reagent (Sigma, Catalog No. 595, prepared as described by the manufacturer, except that a large excess magnesium reagent (about 100x) was used, next to the strip diluting solution, at the application site of the diluting solution. In each case the two liquids flowed towards each other and, when found, formed a discrete interface. The reaction product, a calmagite-magnesium complex having a maximum absorption at 520 nm, was developed at the product interface. Figure 33 is a digital photograph of the test strip of 4.7 mg / dl, which shows the product formation 5 seconds and 295 seconds after the application of the sample to the test strip. These digital images were recorded as described for example 3. The product was detectable after 5 seconds and was substantial after 295 seconds.

EXAMPLE 15 This example illustrates how the present invention was applied to detect and quantify a hapten, thyroxine ("T4"), bound to BSA as an analyte. T4-BSA was bound to mouse anti-T4, conjugated to alkaline phosphatase. In this example, anti-T4-BSA was used at concentrations of 5 μg / ml and 50 μg / ml. Nitrocellulose membranes were washed in Triton X-100 and rinsed with water. T4-BSA was attached to a pad on one side of the fluid transport material, while drying a substrate for alkaline phosphatase, p-nitrophenol phosphate, on a pad at the opposite end of the fluid transport material. Anti-mouse T4 / alkaline phosphatase conjugate was added to the pad containing bound T4-BSA, while adding water simultaneously to the other pad containing the substrate. The liquids flowed towards each other and formed a discrete interface. The reaction product p-nitrophenol was developed at the product interface and measured at 405 nm. Figure 34 is a digital photograph of the product formed from the reaction of the mouse anti-T4 / alkaline phosphatase conjugate with the substrate.

Claims (6)

1. CLAIMS 1. - A device for detecting and quantifying at least one analyte in a fluid sample suspected of containing said analyte, using a liquid reactant capable of reacting with the analyte to form a soluble, detectable reaction product, relating said analyte to the product of soluble, detectable reaction of the analyte and the liquid reactant; characterized in that it comprises: a fluid transport material, capable of absorbing a liquid and causing the capillary flow of the liquid; the fluid transport material having a first zone for the application of the fluid sample that is suspected to contain the analyte; and a second zone for the application of the liquid reactant, where, when the fluid sample is added to the first zone and the liquid reactant is added to the second zone, the fluid sample flows in a first direction from a fluid sample edge towards the second zone; and the liquid reactant flows in a second direction, opposite the first direction and toward the first zone, from a liquid reactant edge; so that, when the fluid flowing sample and the flowing liquid reactant are found, the flow ceases and a detectable reaction product is formed, by a reaction between the liquid reactant and the analyte, and a reaction pattern is formed. stable on a joint between the fluid sample and the liquid reactant, visually distinct from them.
2. 2. The device according to claim 1, further characterized in that the fluid transport material is capable of separating red blood cells from whole blood.
3. 3. The device according to claim 2, further characterized in that the fluid transport material is selected from the group consisting of a HEMASEP L® membrane, a HEMASEP V® membrane, a CYTOSEP® membrane, a SUPOR® membrane, and nitrocellulose.
4. 4. The device according to claim 1, further characterized in that at least one of the first zone and the second zone contains a reagent.
5. 5. The device according to claim 1, further characterized in that the fluid transport material is a nitrocellulose material, cast on a support material.
6. 6. The device according to claim 5, further characterized in that the support material is one of polyvinyl chloride or a polyester film (Mylar ™) 7. The device according to claim 1, further characterized by additionally comprising a pad located in the first zone. 8. The device according to claim 7, further characterized in that the pad is effective to remove red blood cells from the fluid sample. 9. The device according to claim 7, further characterized in that the pad is made of a material selected from the group consisting of Hemasep V and glass fiber 10 - The device according to claim 1, further characterized by additionally comprising means for optionally detecting and measuring an amount of the detectable reaction product 11 - The device according to claim 10, further characterized in that the means for optionally detecting and measuring an amount of the detectable reaction product includes a member selected from the group consisting of of absorbance, reflectance, transmission, fluorescence, luminescence and conductance 12 - The device according to claim 1, further characterized in that it additionally comprises a means for calibrating a concentration of the liquid reagent, said means comprising a calibration zone for the application of a AC nity of the anahto, the calibration zone being located between the first zone and the reaction interface, so that, when the quantity of anate is added to the calibration zone, the analyte in the amount of water flows in one place direction towards the second zone, and the liquid reactant flows in a second direction opposite to the first direction, and towards the first zone, from a liquid reagent edge 13 - The device according to claim 12, further characterized in that the amount of the anahto added to the zone calibration is in excess of the amount of anahto in the fluid sample, such that the amount of anate added to the calibration zone is sufficient to form a quantity of the calibration product that allows the determination of a quantity of the reactant liquid 14 - The device according to claim 1, further characterized in that it additionally comprises a means for simultaneously applying the fluid sample to the first zone and the liquid reactant to the second zone, and a sensor, said sensor being effective for detecting a product Detectable Reaction 15 - The device according to claim 14, further characterized by that the sensor is effective to detect the detectable reaction product having at least a desired wavelength of reflectance or absorption of >; _ 250 nanometers 16 - The device according to claim 14, further characterized in that the sensor is effective to detect and measure an amount of the detectable reaction product that is proportional to an anatole concentration, based on a DICO intensity. of reflectance or absorption of the detectable reaction product 17 - The device according to claim 17, further characterized in that the sensor is effective to detect and measure a rate of formation of the detectable reaction product, which is proportional to the concentration of the analyte . 18.- The device in accordance with the claim 17, further characterized in that the speed is calculated as a change, in time, of a peak intensity of reflectance or absorption of the detectable reaction product. 19.- The device in accordance with the claim 18, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the reaction interface. 20. The device according to claim 18, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising all or a portion of the reaction interface. 21.- The device in accordance with the claim 14, further characterized in that the sensor is effective to detect and measure an amount of the detectable reaction product that is greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicative of the presence of anahto. 22. The device in accordance with the claim 13, further characterized in that the detectable reaction product is formed at a sufficient rate to be detected within about fifteen seconds after the application of the fluid sample to the fluid sample zone. 23. A method for detecting and quantifying at least one analyte in a fluid sample that is suspected of containing said analyte, using a liquid reagent capable of reacting with the analyte to form a soluble, detectable reaction product, relating the analyte to the soluble, detectable reaction product, and the liquid reactant; characterized in said method because it comprises: providing a fluid transport material, capable of absorbing a liquid and causing the capillary flow of the liquid; the fluid transport material having a first zone for the application of the fluid sample suspected of containing the analyte; and a second zone for the application of the liquid reagent; add the fluid sample to the first zone; and the liquid reagent to the second zone; where the fluid sample subsequently flows in a first direction from one edge of the fluid sample to the second zone; and the liquid reagent flows in a second direction, opposite the first direction, and towards the first zone, from a liquid reactive edge; so that the fluid flowing sample and the flowing liquid reactant meet or meet; the flow is stopped and the detectable reaction product is formed, by a reaction between the liquid reactant and the analyte; and a stable reaction interface is formed at a joint between the fluid sample and the liquid reagent, and visually distinct from them; and detecting the detectable reaction product. The method according to claim 23, further characterized in that the fluid transport material is capable of separating red blood cells from whole blood. 25. The method according to claim 24, further characterized in that the fluid transport material is selected from the group consisting of a HEMASEP membrane L®, a HEMASEP V® membrane, a CYTOSEP® membrane, a SUPOR® membrane and nitrocellulose. 26. The method according to claim 23, further characterized in that at least one of the first zone and the second zone contains a reagent. 27. The method according to claim 23, further characterized in that the fluid transport material is a nitrocellulose material, molded into a support material. 28. The method according to claim 27, further characterized in that the support material is one of polyvinyl chloride or a polyester film (Mylar ™). 29. The method according to claim 23, further characterized in that it additionally comprises a pad located in the first zone. 30. The method according to claim 29, further characterized in that the pad is effective to remove red blood cells from the fluid sample. 31. The method according to claim 29, further characterized in that the pad is made of a material selected from the group consisting of Hemasep V and glass fiber. 32. The method according to claim 23, further characterized by additionally comprising measuring an amount of the detectable reaction product. 33. The method according to claim 32, further characterized in that the step of measuring an amount of the detectable reaction product includes measuring a member selected from the group consisting of absorbency, reflectance, transmission, fluorescence, luminescence and conductance. 34.- The method according to claim 32, further characterized in that the detectable reaction product is measured by one of absorbency and reflectance. 35.- The method according to claim 34, further characterized in that the one of absorbance and reflectance is measured at one or more wavelengths of >_250 nanometers. 36. The method according to claim 23, further characterized in that an amount of the detectable reaction product is proportional to a concentration of the analyte, based on a peak intensity of reflectance or absorption of the detectable reaction product. 37. The method according to claim 23, further characterized in that the detectable reaction product is formed at a rate that is proportional to an anahto concentration. 38.- The method according to claim 37, further characterized in that the speed is calculated as a change in time of a peak intensity of reflectance or absorption of the detectable reaction product 39 - The method according to claim 38, characterized in addition because the peak intensity of the reflectance or absorption is measured through a line substantially perpendicular to the reaction interface. The method according to claim 38, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising all or a portion of the reaction interface 41 - The method according to claim 23, further characterized in that the detectable reaction product is formed in an amount greater than or equal to a predetermined minimum reflectance intensity or absorption, indicative of the presence of anahto 42 - The method of according to claim 23, further characterized by additionally comprising measuring a member selected from the group consisting of a distance between the fluid sample edge and a midpoint of the stable reaction interface, a distance between the liquid leactant edge and a midpoint of the stable reaction interface, a distance between the fluid sample edge and a midpoint of a stable liquid interface, a distance between the liquid reactant edge and a midpoint of a stable liquid interface, a distance between the point medium of the stable reaction interface and the midpoint of a stable liquid interface; a reflectance or absorption of the reaction product detectable at a plurality of fixed points in time; a reflectance or absorption of the stable liquid interface, at a plurality of fixed points in time; a rate of change in the reflectance or absorption of the detectable reaction product; an area of the stable reaction interface; an area of stable liquid interface; a bottom level of the fluid sample, and a background level of the liquid reactant. 43. The method according to claim 23, further characterized in that the at least one analyte includes a member selected from the group consisting of glucose, calcium, albumin, alkaline phosphatase, ammonia, bilirubin, uric acid, gamma-glutamyltransferase, amylase, creatine kinase, creatinine, cholesterol, total protein, magnesium, lactate dehydrogenase, lipase, phosphorus, triglyceride, alanine aminotransferase, aspartate aminotransferase and blood urea nitrogen. 44. The method according to claim 23, further characterized in that it further comprises calibrating a concentration of the liquid reagent by applying an amount of the analyte to a calibration zone; the calibration zone being located between the first zone and the reaction interface; whereby, when the amount of analyte is added to the calibration zone, the analyte in said amount of analyte flows in a first direction into the second zone; and the liquid reactant flows in a second direction opposite to the first direction and into the first zone, from a liquid reactant edge; whereby when the analyte flowing in said amount of the analyte and the flowing liquid reactant come together, the flow stops and a detectable calibration product is formed by a reaction between the analyte and the amount of the analyte and the liquid reactant; and a stable calibration reaction interface is formed at a junction between, and visually distinct from, the analyte in said excess amount of the analyte and the liquid reactant; and detecting the detectable calibration product. 45.- The method according to claim 44, further characterized in that the amount of the analyte added to the calibration zone is in excess of the amount of analyte in the fluid sample, such that the amount of analyte added to the The calibration zone is sufficient to form a quantity of the calibration product, which allows the determination of a quantity of liquid reactant. 46. The method according to claim 44, further characterized in that the detectable calibration product is formed at a rate that is proportional to a concentration of the analyte 47. The method according to claim 46, further characterized in that calculates the speed as a change in time of a peak reflectance intensity or absorption of the detectable calibration product. 48. - The method according to claim 47, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the calibration interface. 49. The method according to claim 47, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising all or a portion of the calibration interface. 50.- The method according to claim 44, further characterized in that the detectable reaction product is formed in an amount greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicative of the presence of the analyte. 51.- A device for detecting and quantifying at least one analyte in a fluid sample that is suspected to contain the analyte, using a liquid reactant capable of reacting with the analyte to form a soluble, detectable reaction product, relating the analyte to the detectable soluble reaction product of analyte and liquid reactant, characterized in that it comprises: a fluid transport material, capable of absorbing a liquid and causing the capillary flow of the liquid; said fluid transporting material having a first zone for the application of the fluid sample that is suspected to contain the analyte; and a second zone for the application of a liquid to a pad containing a reconstitutable reagent, where, when the fluid sample is added to the first zone and the liquid is added to the second zone, the fluid sample flows in a first direction from a fluid sample border towards the second zone, the reagent is reconstituted and the reagent and liquid form a liquid reagent containing a liquid reactant capable of reacting with the anahto to form a detectable reaction product, and the liquid reactant flows in a second direction, opposite the first direction and towards the first zone, from a liquid reactant edge, whereby, when the fluid flowing sample and the flowing liquid reactant meet, the flow stops and the product is formed. reaction detectable by a reaction between the liquid reactant and the anahto, and a stable reaction interface is formed in a joint between the fluid sample and the reactant liquid, visually distinct from them 52 - The device according to claim 51, further characterized in that the fluid transport material is capable of separating red blood cells from whole blood 53 - The device according to claim 52, further characterized because the fluid transport material is selected from the group consisting of a HEMASEP L® membrane, a HEMASEP V® membrane, a CYTOSEP® membrane, a SUPOR® membrane and nitrocellulose 54 - The device according to claim 51, further characterized because at least one of the first zone and the second zone contains a reagent. 55.- The device according to claim 51, further characterized in that the bibulous material is a nitrocellulose material, molded on a support material. 56.- The device in accordance with the claim 55, further characterized in that the support material is one of polyvinyl chloride or a polyester film (Mylar ™). 57.- The device according to claim 51, further characterized in that it additionally comprises a pad located in the first zone. 58.- The device according to claim 57, further characterized in that the pad is effective to remove red blood cells from the fluid sample. 59. The device according to claim 57, further characterized in that the pad is made of a material selected from the group consisting of Hemasep V and glass fiber. The device according to claim 51, further characterized in that it additionally comprises a means for detecting and optionally means an amount of the detectable reaction product. 61.- The device in accordance with the claim 60, further characterized in that the means for detecting and optionally measuring an amount of the detectable reaction product include a member selected from the group consisting of absorbency, reflectance, transmission, fluorescence, luminescence and conductance. 62 - The device according to claim 51 , characterized in that it additionally comprises a calibration zone for application of an anahto quantity, the calibration zone being located between the first zone and the reaction interface, whereby, when the quantity of anato is added to the zone of calibration, the anahto in said amount of analyte flows in a first direction towards the second zone, and the liquid reactant flows in a second direction, opposite the first direction and towards the first zone, from a liquid reactant edge, thereby , when the anahto flowing in said amount of analyte and the liquid reactant flowing are found, stop the flow and a detectable calibration product is formed by a reaction between the analyte in said amount of analyte and the liquid reactant, and a stable calibration reaction interface is formed at a junction between the anahto in the amount of anahto and the liquid reactant, visually distinct from them, the calibration interface being additionally adjacent to the reaction interface 63 - The device according to claim 62, further characterized in that the amount of anahto added to the calibration zone is in excess of the amount of anahto in the fluid sample, so that the amount of anahto added to the calibration zone is sufficient to form a quantity of the calibration product that allows the determination of an amount of the liquid reactant 64 - The device according to claim 51 , further characterized in that it additionally comprises a means for simultaneously applying the a fluid sample to the first zone and the liquid reactant to the second zone, and a sensor, the sensor being effective to detect the detectable reaction product 65 - The device according to claim 64, further characterized in that the sensor is effective for detecting the detectable reaction product, having at least one wavelength of reflectance or absorption of > .250 nanometers 66 - The device according to claim 64, further characterized in that the sensor is effective to detect and measure an amount of the detectable reaction product, which is proportional to an anahto concentration based on a peak reflectance intensity or absorption of the detectable reaction product 67 - The device according to claim 64, further characterized in that the sensor is effective to detect and measure a rate of formation of the detectable reaction product, which is to provide the concentration of the analyte 68 - The device according to claim 67, further characterized in that the speed is calculated as a change over time of a peak intensity of reflectance or absorption of the detectable reaction product. 69.- The device according to claim 68, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the reaction interface. The device according to claim 68, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising the entire reaction interface or a portion of it ..}. 71.- The device in accordance with the claim 64, further characterized in that the sensor is effective to detect and measure an amount of the detectable reaction product, which is greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicative of the presence of the analyte. 72.- A method to detect and quantify at least one analyte in a fluid sample that is suspected to contain the analyte, employing a liquid reactant capable of reacting with the analyte to form a soluble, detectable reaction product, relating the anahto with the soluble, detectable reaction product and the liquid reactant, characterized in that it comprises: providing a fluid transport material, capable of of absorbing a liquid and causing the liquid to flow capillary; the fluid transport material having a first zone for the application of the fluid sample suspected of containing the anahto, and a second zone for the application of a liquid to a pad containing a reconstitutable reagent, where, when the fluid sample to the first zone and the liquid is added to the second zone, the fluid sample flows in a first direction, from a fluid sample edge to the second zone, the reagent is reconstituted and the reagent and liquid form a liquid reagent which contains a liquid reactant capable of reacting with the anahto to form a detectable reaction product, and the liquid reactant flows in a second direction, opposite the first direction and into the first zone from a liquid reactant edge, thereby, When the fluid flowing sample and flowing liquid reactant are found, the flow is stopped and the detectable reaction product is formed by a action between the liquid reactant and the anate, and a stable reaction interface is formed in a joint between the fluid sample and the liquid reactant, visually distinct from them, and detect the detectable calibration product 73 - The method of conformity with the claim 72, further characterized in that the fluid transport material is capable of separating red blood cells from whole blood 74 - The method according to claim 73, further characterized in that the fluid transport material is selected from the group consisting of a HEMASEP L® membrane, a HEMASEP V® membrane, a CYTOSEP® membrane, a SUPOR® membrane and nitrocellulose 75 - The method according to claim 72, further characterized in that at least one of the first zone and the second zone contains a reagent 76 - The method according to claim 72, further characterized in that the fluid transport material is a nit material rocellulose, molded on a support material 77 - The method according to claim 76, further characterized in that the support material is one of polyvinyl chloride or a polyester film (Mylar ™) 78 - The method according to claim 72, further characterized in that it further comprises providing a pad located in the first zone 79 - The method according to claim 78, further characterized in that the pad is effective to separate the red blood cells from the fluid sample 80 - The method according to claim 78 , further characterized in that the pad is made of a material selected from the group consisting of Hemasep V and glass fiber 81 - The method according to claim 72, further characterized in that it additionally comprises measuring an amount of the detectable reaction product 82 - method according to claim 81, character further bristling because the step of measuring an amount of the detectable reaction product includes measuring a member selected from the group consisting of absorbency, reflectance, transmission, fluorescence, luminescence and conductance. 83. The method according to claim 81, further characterized in that the detectable reaction product is measured by one of absorbency and reflectance. 84. The method according to claim 83, further characterized in that one of absorbance and reflectance is measured at one or more wavelengths of > _ 250 nanometers. } The method according to claim 72, further characterized in that an amount of the detectable reaction product is proportional to a concentration of the analyte based on a peak intensity of reflectance or absorption of the detectable reaction product. 86. The method according to claim 72, further characterized in that the detectable reaction product is formed at a rate that is proportional to an anahto concentration. 87.- The method according to claim 86, further characterized in that the speed is calculated as a change over time of a peak reflectance intensity or absorption of the detectable reaction product. 88. The method according to claim 87, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the reaction interface. 89.- The method according to claim 87, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising all or a portion of the reaction interface 90 - The method according to claim 72, further characterized in that the detectable reaction product is formed in an amount greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicative of the presence of anahto 91 - The method according to claim 72, further characterized in that the reaction product forms detectable at a sufficient rate to be detected within about fifteen seconds after the application of the fluid sample to the fluid sample zone 92 - The method according to claim 72, further characterized by additionally comprising measuring a member selected from the group consisting of a dis between the fluid sample edge and a midpoint of the stable reaction interface, a distance between the liquid reactant edge and a midpoint of the stable reaction interface, a distance between the fluid sample edge and a spot point of a stable liquid interface, a distance between the liquid reactant edge and a midpoint of a stable liquid interface, a distance between the midpoint of the stable reaction interface and the midpoint of a stable liquid interface, a reflectance or absorption of the reaction product detectable at a plurality of fixed points in time; a reflectance or absorption of the stable liquid interface, at a plurality of fixed points in time; a rate of change in the reflectance or absorption of the detectable reaction product; an area of the stable reaction interface; an area of stable liquid interface; a bottom level of the fluid sample, and a background level of the liquid reactant. The method according to claim 72, further characterized in that said at least one analyte includes a member selected from the group consisting of glucose, calcium, albumin, alkaline phosphatase, ammonia, bilirubin, uric acid, gamma-glutamyltransferase , amylase, creatine kinase, creatinine, cholesterol, total protein, magnesium, lactate dehydrogenase, lipase, phosphorus, triglyceride, alanine aminotransferase, aspartate aminotransferase and urea nitrogen in blood. 94. The method according to claim 72, further characterized in that it further comprises calibrating a concentration of the liquid reagent by applying an amount of the analyte to a calibration zone; the calibration zone being located between the first zone and the reaction interface; whereby, when the amount of analyte is added to the calibration zone, the analyte in the amount of analyte flows in a first direction towards the second zone; and the liquid reactant flows in a second direction, opposite the first direction, and toward the first zone, from a liquid reactant edge; whereby, when the analyte flowing in said quantity of anahto and the flowing liquid reactant meet, the flow stops and a detectable calibration product is formed by a reaction between the analyte in the amount of the analyte and the liquid reactant; and a stable calibration reaction interface is formed, at a junction between the analyte in said amount of analyte and the liquid reactant, visually distinct from them; the calibration interface being additionally adjacent to the reaction interface; and measuring the calibration product therein, at least at a desired wavelength of reflectance or absorbency, as said reaction product. The method according to claim 94, further characterized in that the amount of analyte added to the calibration zone is in excess of the amount of analyte in the fluid sample; so that said amount of analyte added to the calibration zone is sufficient to form a quantity of the calibration product that allows the determination of an amount of the liquid reactant. 96. The method according to claim 94, further characterized in that the detectable calibration product is formed at a rate that is proportional to the concentration of the analyte. The method according to claim 96, further characterized in that said speed is calculated as a change over time of a peak intensity of reflectance or absorption of the detectable calibration product. 98., - The method according to claim 97, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the reaction interface 99. The method according to claim 97, characterized in addition because the peak intensity of reflectance or absorption is measured within a polygonal region comprising all or a portion of the reaction interface. The method according to claim 94, further characterized in that the detectable reaction product is formed in an amount greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicative of the presence of the analyte. 101.- A device for detecting and quantifying at least one anahto in a fluid sample that is suspected to contain the analyte, using a reagent capable of binding to the analyte and forming a detectable reaction product from a substrate, to relate a amount of the anahto with a quantity of the detectable reaction product, characterized in that it comprises: a fluid transport material, capable of absorbing a liquid and causing the capillary flow of the liquid; the fluid transport material having a first zone for the application of the fluid sample containing the reagent to a first pad containing the analyte substantially irreversibly attached to the first pad, and a second zone for the application of a liquid to a liquid. second pad containing a reconstitutable substrate, where, when the fluid sample containing the reagent is added to the first pad and the liquid is added to the second pad, the fluid sample containing the reagent not bound to the analyte attached substantially irreversibly to the first pad, it flows in a first direction from a fluid sample edge to the second zone; and the substrate is reconstituted by the liquid to form a liquid reactant capable of reacting with the reagent; and the liquid reactant flows in a second direction opposite to the first direction and into the first zone from a liquid reactant edge; whereby, when the fluid flowing sample containing the unbound reagent by the analyte substantially irreversibly bound to the first pad and the flowing liquid reactant meet, the flow is stopped and the detectable reaction product is formed by a reaction between the liquid reactant and the reagent; and a stable reaction interface is formed in a joint between the fluid sample and the liquid reactant, visually distinct from them. 102.- The device according to claim 101, further characterized in that the fluid transport material is selected from the group consisting of a HEMAEP L® membrane, a HEMASEP V® membrane, a CYTOSEP® membrane, a SUPOR® membrane and nitrocellulose 103. - The device according to claim 101, further characterized in that the fluid transport material is a nitrocellulose material, molded on a support material. 104.- The device in accordance with the claim 103, further characterized in that the support material is one of polyvinyl chloride or a polyester film (Mylar®). The device according to claim 101, further characterized in that it comprises a means for detecting and optionally measuring an amount of the detectable reaction product. 106. The device according to claim 101, further characterized in that it comprises a means for calibrating a concentration of the liquid reagent; said means comprising a calibration zone for application of a quantity of the reagent; the calibration zone being located between the first zone and the reaction interface; whereby, when the amount of the reagent is added to the calibration zone, the reagent flows in a first direction tos the second zone; and the liquid reactant flows in a second direction opposite to the first direction and to the first zone, from a liquid reactant edge; whereby, when the reactant flowing from the flowing liquid reactant is encountered, the flow is stopped and a detectable calibration product is formed, by a reaction between the reactant and the liquid reactant, and a reaction interface is formed of stable calibration in a joint between the reactant in said amount of reagent and the liquid reactant, visually distinct from them. 107. The device according to claim 106, further characterized in that the amount of reagent added to the calibration zone is in excess of the amount of the reagent in the fluid sample, such that said amount of reagent added to the area of Calibration is sufficient to form a quantity of the detectable calibration product, which allows the determination of a quantity of the liquid reactant. 108.- The device in accordance with the claim 101, further characterized in that it further comprises: a means for simultaneously applying the fluid sample to the first zone and the liquid reactant to the second zone; and a sensor; said sensor being effective to detect the detectable reaction product. 109. The device according to claim 108, further characterized in that the sensor is effective to detect the detectable reaction product having at least a desired wavelength of reflectance or absorption of > 250 nanometers 110.- The device according to claim 108, further characterized in that the sensor is effective to detect and measure an amount of the detectable reaction product that is proportional to a concentration of the analyte, based on a peak intensity of reflectance or absorption of the detectable reaction product. 111. The device according to claim 108, further characterized in that the sensor is effective to detect and measure the rate of formation of the detectable reaction product, which is proportional to the concentration of the analyte. 112.- The device in accordance with the claim 111, further characterized in that the velocity is calculated as a change with time of the peak reflectance intensity or absorption of the detectable reaction product. 113.- The device in accordance with the claim 112, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the reaction interface. 114. The device according to claim 112, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising all or a portion of the reaction interface. 115.- The device in accordance with the claim 108, further characterized in that the sensor is effective to detect and measure an amount of the detectable reaction product that is greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicative of the presence of the analyte. 116.- The device in accordance with the claim 107, further characterized in that the detectable reaction product is formed at a sufficient rate to be detected within about fifteen seconds after the application of the fluid sample to the fluid sample zone. 117. The device according to claim 101, further characterized in that the reagent comprises an enzyme or a portion thereof, linked to a monoclonal antibody or a portion thereof; the enzyme or a portion thereof being capable of forming the reaction product detectable from said substrate; the monoclonal antibody or a portion thereof being capable of binding to the analyte. The device according to claim 117, further characterized in that the enzyme is a member selected from the group consisting of alkaline phosphatase, beta-galactosidase and peroxidase. 119.- The device in accordance with the claim 117, further characterized in that the portion of a monoclonal antibody is selected from the group consisting of an F (ab) fragment, an F (ab ') fragment, an F (ab') 2 fragment, an Fv fragment and an scFv fragment. 120.- The device in accordance with the claim 101, further characterized in that the reagent comprises an enzyme or a portion thereof linked to a receptor protein or a portion thereof; the enzyme or its portion being capable of forming the reaction product detectable from said substrate; the receptor protein or its portion binding to said analyte being capable. 121. The device according to claim 101, further characterized in that the reagent comprises an enzyme or a portion thereof, linked to an abstida or a portion thereof; the enzyme or its portion being capable of forming the reaction product detectable from said substrate; the abstida or its portion being able to bind said analyte. 122.- A method for detecting and quantifying at least one analyte in a fluid sample that is suspected of containing the analyte, using a reagent capable of binding to the analyte and forming a detectable reaction product from a substrate, to relate a amount of the analyte with a quantity of the detectable reaction product, characterized in that it comprises: providing a fluid transport material, capable of absorbing a liquid and causing the capillary flow of the liquid; the fluid transport material having a first zone for the application of the fluid sample containing the reagent to a first pad containing the analyte substantially irreversibly bound to the first pad and a second zone for the application of a liquid to a liquid. second pad containing a reconstitutable substrate; adding the fluid sample containing the reagent to the first pad and the liquid to the second pad; where the fluid sample, after this flows in a first direction from a fluid sample edge to the second zone, and the substrate is reconstituted by the liquid to form a liquid reactant, capable of reacting with the reagent, and the liquid reactant flows in a second direction opposite to the first direction and to the first zone, from a liquid reactant edge, whereby, when the fluid sample flowing, it contains the reagent not attached by the anahto substantially irreversibly to the first pad , and the flowing liquid reactant is found, the flow is stopped and the detectable reaction product is formed by a reaction between the liquid reactant and the reactant, and a stable reaction interface is formed at a joint between the fluid sample and the liquid reactant, visually distinct from them, and detect the detectable reaction product 123 - The method according to claim 122, further characterized in that the transport material is selected from the group consisting of a membrane HEMASEP L® a membrane HEMASEP V® a membrane CYTOSEP®, a SUPOR® membrane and nitrocellulose 124 - The method according to claim 122, further characterized in that the fluid transport material is a nitrocellulose material molded into a support material 125 - The method according to claim 124 , further characterized in that the support material is one of pohvmyl chloride or a polyester film (Mylar ™) 126. - The method according to claim 122, further characterized by additionally comprising measuring an amount of the detectable reaction product. 127. The method according to claim 122, further characterized in that the step of measuring an amount of the detectable reaction product includes measuring a member selected from the group consisting of absorbency, reflectance, transmission, fluorescence, luminescence and conductance. 128. The method according to claim 122, further characterized in that the detectable reaction product is measured by one of absorbency and reflectance. 129.- The method according to claim 128, further characterized in that one of absorbance and reflectance is measured at one or more wavelengths of > .250 nanometers 130. The method according to claim 126, further characterized in that the amount of detectable reaction product is proportional to a concentration of the analyte based on a peak intensity of reflectance or absorption of the detectable reaction product. 131. The method according to claim 122, further characterized in that the detectable reaction product is formed at a rate that is proportional to a concentration of the analyte. 132. The method according to claim 131, further characterized in that the speed is calculated as a change in time of a peak intensity of reflectance or absorption of the detectable reaction product. 133. The method according to claim 132, further characterized in that the peak intensity of reflectance or absorption is measured through a line substantially perpendicular to the reaction interface. 134. The method according to claim 132, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising the entire reaction interface or a portion thereof. The method according to claim 122, further characterized in that the detectable reaction product is formed in an amount greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicating the presence of the analyte. The method according to claim 122, characterized in that it additionally comprises measuring a member selected from the group consisting of: a distance between the fluid sample edge and a midpoint of the stable reaction interface; a distance between the liquid reactant edge and a midpoint of the stable reaction interface; a distance between the fluid sample edge and a midpoint of a stable liquid interface; a distance between the liquid reactant edge and a midpoint of a stable liquid interface; a distance between the midpoint of the stable reaction interface and the midpoint of a stable liquid interface; a reflectance or absorption of the reaction product detectable at a plurality of fixed points in time; a reflectance or absorption of the stable liquid interface, at a plurality of fixed points in time; a rate of change in the reflectance or absorption of the detectable reaction product; an area of the stable reaction interface; an area of stable liquid interface; a bottom level of the fluid sample, and a background level of the liquid reactant. The method according to claim 122, further characterized in that it further comprises calibrating a concentration of the liquid reagent by applying a quantity of the reagent to a calibration zone; the calibration zone being located between the first zone and the reaction interface, so that when the reagent is added to the calibration zone the reagent flows in a first direction towards the second zone and the liquid reactant flows in a second direction, opposite the first direction and towards the first zone, from a liquid reactant edge; so that the reagent flowing from the flowing liquid reactant will meet, stop the flow and form a detectable calibration product, by a reaction between the reactant and the liquid reactant, and form a stable calibration reaction interface in a joint between the reagent in said excessive amount of reagent and the liquid reactant; visually distinct from them; and detecting the detectable calibration product. 138. The method according to claim 137, further characterized in that the amount of reagent added to the calibration zone is in excess of the amount of reagent in the fluid sample; so that the amount of reagent added to the calibration zone is sufficient to form a quantity of the detectable calibration product, which allows the determination of an amount of the liquid reactant. 139. The method according to claim 137, further characterized in that the detectable calibration product is formed at a rate that is proportional to a concentration of the reagent. The method according to claim 139, further characterized in that the speed is calculated as a change in time of a sharp intensity of reflectance or absorption of the detectable calibration product. 141. The method according to claim 140, further characterized in that the intensity of reflectance or absorption is measured through a line substantially perpendicular to the calibration interface. 142 - The method according to claim 140, further characterized in that the peak intensity of reflectance or absorption is measured within a polygonal region comprising the entire calibration interface or a portion thereof. 143. - The method according to claim 137, further characterized in that the detectable calibration product is formed in an amount greater than or equal to a predetermined minimum intensity of reflectance or absorption, indicating the presence of the reagent. 144. The method according to claim 122, further characterized in that the reagent comprises an enzyme or a portion thereof conjugated to a monoclonal antibody or a portion thereof; the enzyme or its portion being capable of forming the detectable reaction product from the substrate; the monoclonal antibody or its portion of binding to the anahto being capable. 145. The method according to claim 144, further characterized in that the enzyme is a member selected from the group consisting of alkaline phosphatase, beta-galactosidase and peroxidase. 146. The method according to claim 144, further characterized in that the portion of a monoclonal antibody is selected from the group consisting of an F (ab) fragment, an F (ab ') fragment, an F (ab') fragment. 2, a Fv fragment and a scFv fragment. 147. The method according to claim 122, further characterized in that the reagent comprises an enzyme or a portion thereof, conjugated to a receptor protein or a portion thereof; the enzyme or its portion being capable of forming the detectable reaction product from the substrate; the receptor protein or its portion being able to bind to the analyte. 148. The method according to claim 122, further characterized in that the reagent comprises an enzyme or a portion thereof, conjugated to an abstid or a portion thereof; the enzyme or its portion being capable of forming the detectable reaction product from the substrate; the abstida or its portion being able to bind to the analyte.