ES2389196T3 - Dry stick device and method to determine an analyte in a sample - Google Patents

Abstract

A dry stick test device for the determination of an analyte in a milk sample by means of a chemical test, said device comprises: (i) optionally a solid support, (ii) at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when in the wet state, (iii) a developer pad that is located in contact with the at least one reactive pad, optionally between the solid support and the at least one reactive pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal, wherein the developer pad is located downstream of the at least one reactive pad in which the at least one reactive pad and the pillow The developer is arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device and where the sample is applied on the upper face of the device and the detectable signal is obtained from the face upper of the device and wherein the control compound is an acid compound capable of providing a pH value of the milk sample below 6 and where the upper face of the device is related to the surface where the sample is initially placed in contact with the at least one test pad.

Description

Dry stick device and method to determine an analyte in a sample.

FIELD OF THE INVENTION

 The present invention relates to the field of analysis of an analyte in a milk sample. Particularly, the present invention relates to an improved construction of a dry stick device for the determination of an analyte in a milk sample by using a chemical test, where particular care is taken to avoid the precipitation of the components of the milk sample on the upper face of the device causing detectable seral limitation.

PREVIOUS ART

 Dairy herd improvement (DHI) has always been based on the registration of the milk of individual cows in a herd. By increasing this knowledge of each individual cow, it is possible to increase the quantity and improve the quality of the milk. In addition, the general health situation is improved and with it the income of the farmers will increase. One way for farmers to increase their income may be to optimize food by monitoring urea content. In the breeding of dairy cows, it is very important that animals (for example, cows) optimally utilize the protein content of the feed, since the protein is one of the most expensive components of the feed. The use depends, among others, on the amount of energy and protein simultaneously present in the animal. When a food contains more protein than necessary, not all the ammonia formed there can be processed in the belly. The excess of ammonia is absorbed by the blood and discharged into the liver where the ammonia is converted to urea (CO (NH2) 2). This urea is absorbed into the blood and widely excreted through the urine. From the blood, a small part of the urea also finds its way to the milk. In a cow that produces 25 kg of milk, the urea content is generally about 5 to 8 g urea per 25 kg of milk or (0.2 to 0.3 g / l). The more ammonia in the belly, the more urea in the blood, which means more urea in the milk. Excess protein (which also provides excess nitrogen, because the protein includes nitrogen) in the feed leads to a higher urea content in the milk. Consequently, from the point of view of the use of nitrogen, a lower urea content is desirable. However, there is also a lower limit. A low content of improper urea indicates a relationship of improper energy in the diet or a low content of improper protein in the diet. If the animals feed less they will produce less milk than they are capable and / or the protein content in the milk decreases. Another important point may be that energy is required to process the urea. In other words, a high nitrogen balance is also energetically unfavorable. There is a direct relationship between the amount of protein fed and the concentration of urea in the blood and milk. The high results of MUN (urea nitrogen in milk) indicate an opportunity to reduce the protein content of the diet, without reducing milk production. This will reduce food costs and also reduce the release of nitrogen to the environment. Overfeeding with proteins, which results in high levels of urea in milk, will have the following consequences:

Energy is needed for cows to synthesize urea for excretion Reduction of the amount of energy available for milk production Less energy available can put the onset of breastfeeding at increased risk of ketosis The high level of urea is toxic to sperm and the embryo and may result in reduced fertility. High urea levels contribute to environmental pollution. Today, many farmers supercharge protein at 10-20%. Protein overfeeding by 20% will lead to a cost increase of approximately USD 50 / cow / hoop. The information given by the farmers when observing the urea nitrogen in the milk will provide the basis for decisions on how to change the feeding, especially concerning the energy / protein ratio (see the table below). Because MUN levels are affected by a large number of factors related to cows, including age, lactation stage, health status, water consumption and dry matter intake, cows fed the same ration frequently have Very different MUN values. Therefore, it is generally recommended to use the MUN results of a minimum of 10 cows to diagnose feeding problems.

All information on the milk samples provided in the urea content, plus many other data of the individual cows, can be stored in or on several databases. A number of databases can be linked and can be used by consultants, veterinarians, consultants and others without visiting the farms. The information can be used to compare the situation in different countries, improve reproduction values, optimize feeding and reduce the problem with insufficient feeding.

Thus, the determination of urea in a sample has become increasingly popular and technologies that allow the measurement of a large number of samples and urea nitrogen in milk (MUN) are frequently used as an indicator of ammonia levels in belly. The content of MUN is an accurate and rapid reflection of the amount of nitrogen absorbed by the cow but is not used for the growth or synthesis of milk protein. The determination of urea content in a sample using enzymes based on test devices such as Reflotest and AzotesttStrip / Azostix are well known to a person with experience in the industry. Both Reflotest and AzotesttStrip / Azostix use urease and azo dyes to determine urea in a sample.

The urea content in a sample can also be determined using a chemical assay that uses coloring agents such as o-phthalaldehyde, such chemical assays are well known to the person with experience in the industry. Frequently, chemical assays involve control compounds / compounds (such as acids) that can cause precipitation of the sample components.

US 4,215,995 describes test means for determining the urea content in a sample. The test media involves a single filter paper that is impregnated in a three-stage reagent application (including o-phthalaldehyde) separated from each other by an acid modified carrier matrix. In this way, superior reagent stability is achieved and the precipitation of whey proteins can be avoided by providing a suitable acid matrix using a paper loaded with a strong cation exchanger. The problem with the device provided by US 4,215,995 is that the acidity component is not isolated from the reagents and will be contacted directly with pH-sensitive liquid samples which can cause precipitation of the sample components on the upper face of the device. and thus reduce the readable seral.

Patent application JP 10-229023 describes a test device comprising a solid support and a test pad and a developer pad for the determination of urea in a sample, such as blood, serum

or plasma The reaction pad is impregnated with o-phthalaldehyde glycerin acetal, polyvinyl pyrrolidone and distilled water. The developer pad is impregnated with N-1-naphthyl-N'-diethylethylenediamine oxalate, 4-sulfophthalic acid in an aqueous solution, a surfactant and distilled water. The test pad is then coated on the solid support, the developer pad is coated on this reaction pad. The problem with using this or a similar test device for the determination of urea in a sample such as milk is that the acid impregnated in the developer pad (the top layer) causes milk proteins to precipitate on the top of the device . This precipitation interferes with the development of color when urea is determined and may increase the numbers of false results.

Thus, there is a need in the industry for a construction of simple dry swabs where the interference of precipitated sample components is limited or avoided.

SUMMARY OF THIS INVENTION

Accordingly, in a first aspect, the objective of the present invention is to provide a dry stick test device for the determination of an analyte in a milk sample by means of a chemical test wherein said dry stick device is constructed of way of limiting or preventing precipitation of the component (s) of the milk sample. The dry stick test device comprises:

(i)

optionally a solid support,

(ii)

at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state,

(iii) a developer pad that is located in contact with the at least one reactive pad, optionally between the solid support and the at least one reactive pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent reacts with the analyte to provide a detectable signal,

wherein the at least one test pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device and where the sample is applied on the upper face of the device and a detectable signal is obtained from the upper face of the device and wherein the control compound is an acidic compound capable of providing a pH value of the milk sample below 6 and where the upper face of the device is related with the surface where the sample is initially contacted with the at least one reactive pad.

In another aspect of the present invention, a dry stick test device is provided for the determination of an analyte in a milk sample by means of a chemical test. The dry stick test device comprises:

(i)

 optionally a solid support,

(ii)

 at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state,

(iii) a developer pad that is located in contact with the at least one test pad, optionally between the solid support and the test pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal,

wherein the at least one test pad is capable of providing a pH value of the milk sample of 6 or above 6 to prevent precipitation of the sample component (s), and the control compound present in the developer pad is capable of providing a pH value of the milk sample below 6, wherein the at least one reactive pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device, where the sample is applied on the upper face of the device and the detectable seral is obtained from the upper face of the device that relates to the surface where the sample is initially contacted with the at least one test pad. Furthermore, it is an aspect of the present invention to provide a dry stick test device for the determination of urea in a milk sample, said dry stick test device optionally comprises a solid support and at least 2 pads, said at least 2 pads comprise (i) at least one reactive pad comprising o-phthalaldehyde or a derivative thereof, a coloring compound and a detergent, and (ii) a developer pad comprising at least one acid, wherein the developer pad is located downstream of the at least one test pad.

It is also the object of the present invention to provide a method for the preparation of the dry stick device according to the present invention. The method comprises the steps of:

(i)

providing at least one reactive pad by impregnating a first porous material with an aqueous solution comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when in the wet state,

(ii)

 after that dry the at least one test pad,

(iii) providing a developer pad by impregnating a second porous material with an aqueous solution comprising at least one control compound which, when in a wet state, is capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal,

(iv)

after that dry the second impregnated porous material

(v)

immobilize the first porous material with the second porous material, optionally on a solid support, to obtain the dry stick device.

In a further objective of the present invention, a method is provided for the determination of an analyte in a milk sample. The method comprises the steps of:

(to)

applying the sample suspected of containing the analyte to the dry stick test device, said dry stick test device comprises:

(i)

at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state, and

(ii)

in contact with said at least one reactive pad a developer pad is located, said developer pad comprises at least one control compound capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal, wherein the at least a test pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device.

(b)

allow the sample to migrate into the at least one reagent pad and the developer pad and mobilize the at least one reagent and the at least one control compound, and

(C)

 allow the at least one reagent and the analyte, the derivative of said analyte or the indicator compound for said analyte to react and provide a detectable signal.

The present invention will now be described in more detail below.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The inventors of the present invention surprisingly found and developed a new construction of a dry stick test device where interference from the precipitated components of the milk sample is limited or prevented.

The new construction of the dry stick test device for the determination of an analyte in a milk sample by means of a chemical test comprises: (i) optionally a solid support, (ii) at least one reactive pad comprising a reagent or a combination of reagents capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when in the wet state, (iii) a developer pad that is located in contact with the at least one reactive pad, optionally between the solid support and the at least one reactive pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal, wherein the pad developer is located downstream of the at least one test pad, where the at least one almoh Reactive adilla and developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device and where the sample is applied on the upper face of the device and seral is obtained detectable from the upper face of the device and wherein the control compound is an acid compound capable of providing a pH value of the milk sample below 6 and where the upper face of the device is related to the surface where the sample It initially contacts the at least one test pad. In one embodiment of the present invention, the at least one reactive pad comprises a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte and / or a reagent capable of participating in the determination of the analyte. The reagent capable of participating in the determination of the analyte may be a reagent that takes part in the assay to provide a detectable signal, but that does not bind, react or interact directly with the analyte.

In the present context, the term "chemical test" refers to the determination of the relative amounts of one or more components of the milk sample by means of a chemical and / or biochemical reaction. In one embodiment of the present invention, the chemical assay involves the determination of the analyte that is not based on an enzyme-based determination.

An enzyme-based assay is an assay that depends on or uses enzymatic activity to produce a detectable signal.

As mentioned above, the dry stick test device comprises at least one reagent pad and a developer pad wherein the at least one reagent pad comprises the reagent or the combination of reagents and the developer pad comprises at least one control compound capable of provide a condition required for the reagent or reagent combination to react with the analyte to provide a detectable signal. In one embodiment of the present invention, the at least one reagent and the developer pad are located in relation to each other so that precipitation of the components of the milk sample can be avoided, particularly to prevent precipitation of the components of the milk sample on the surface, where the reading / determination (of color) is performed.

In the present context the term "arranged to avoid precipitation" refers to placing the at least one reactive pad and the developer pad so as to avoid the precipitation of the components of the milk sample on the upper face of the test device. of dry stick when the sample is applied. Precipitation of the components of the milk sample means the components of the milk sample of the fluid milk sample or part of the fluid milk sample that changes to solid or semi-solid mass, often caused by the action of, for example, , heat or chemicals. It is preferred that precipitation be provided by the action of a chemical substance (in the present context a control compound).

In the present context the term "upper face" refers to the surface of the dry swab device according to the present invention where the milk sample is applied or where the milk sample is initially contacted with the at least one pad reactive

In an alternative embodiment of the present invention the term "upper face" refers to the surface of the dry stick test device of the present invention from which the detectable signal is obtained. This surface is the same as the surface where the sample is applied.

In one embodiment of the present invention, the dry stick test device may comprise at least 2 reactive pads, such as at least 3 reactive pads, for example, at least 4 reactive pads, such as at least 5 reactive pads, for example , at least 6 reactive pads.

In the present context, the term "sample components" refers to all substances present in the milk sample at the time of testing, in one embodiment of the present invention the "sample components" may be one of reagents of the assay. In one embodiment of the present invention the components of the milk sample that may tend to precipitate may be milk proteins, such as casein molecules.

The inventors of the present invention also provided a new method for the determination of an analyte in a milk sample. The method comprises the steps of:

(to)

applying the sample suspected of containing the analyte to the dry stick test device, said dry stick test device comprises:

(i)

at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state, and

(ii)

in contact with said at least one reactive pad a developer pad is located, said developer pad comprises at least one control compound capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal, wherein the at least a reactive pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device and where the sample is applied on the upper face of the device and the detectable signal from the upper face of the device and wherein the control compound is an acid compound capable of providing a pH value of the milk sample below 6 and where the upper face of the device is related to the surface where the sample is initially contacted with the at least one test pad

(b)

allow the sample to migrate into the at least one reagent pad and the developer pad and mobilize the at least one reagent and the at least one control compound, and

(C)

 allow the at least one reagent and the analyte, the derivative of said analyte or the indicator compound for said analyte to react and provide a detectable signal.

The detectable signal can be any substance that is directly or indirectly capable of being observed by any type of visual or instrumental means. The instrumental means can be, for example, a magne (magne) tometro, spectrophotometer, reader-ELISA. Several appropriate compounds may be suitable as the compound that produces color. In the present invention, the color-producing compound may be selected from the group consisting of chromogens, catalysts, fluorescent compounds, chemiluminescent compounds, radioactive tags, metals, magnetic particles, coloring particles, organic polymer latex particles, liposomes or other vesicles that they contain substances that produce seral and the like.

In the present context the term "in a wet state" refers to the contact between the reagents in the reagent pad (s) and / or the control compound in the developer pad and the milk sample where the reagent pad (s) and / or the developer pad are moistened or slightly moistened. The effect of the wet state is that the dry reagents, the dry control compounds are released and dissolved (mobilized) and the reaction in the dry stick device begins and a detectable seral occurs, which depends on the amount of analyte present in the milk sample

The porous matter

The materials selected for use in the at least one reactive pad and / or the developer pad may be selected from a porous material. In the present context the term "porous material" refers to a material that absorbs the milk sample and thus allows it to migrate.

The selected porous material may comprise a pore size and a capacity that makes it possible to provide a high flow rate that rapidly dissolves the reagent or the combination of reagents and provides a good and substantially uniform distribution of the samples. Preferably, the porous material can be selected so that it substantially does not provide retention of triglyceride-rich samples. In one embodiment of the present invention the retention of triglycerides is 0%, such as a maximum of 1%, for example, a maximum of 2.5%, such as a maximum of 5%, for example, a maximum of 10%, such as a maximum of 15%, for example, a maximum of 25%, such as a maximum of 50%, or the retention of most or all triglycerides, for example, a maximum of 75%, such as a maximum of 100 %.

The porous material is selected from the group consisting of a nitrocellulose membrane, cellulose, a polymer (such as nylon, polyvinylidene fluoride or latex), glass fiber, tissue fibers, nonwoven fibers, a chromatographic gel membrane, earth of diatoms, silica gel, silicon oxide and diatomite.

In one embodiment of the present invention, the porous material in the at least one reactive pad and / or in the developer pad may be selected from a group of materials comprising a pore size preferably in the range of 1-1000 µm, such as in the range of 1-500 µm, such as in the range of 1-100 pm, for example, in the range of 1-75 µm, such as in the range of 5-500 µm, as in the range of 5-100 µm, for example, in the range of 5-75 µm, such as in the range of 10-500 µm, such as in the range of 10-100 µm, for example, in the range of 10-75 µm, such as in the range of 10-50 µm, for example, in the range of 50-200 µm, such as in the range of 50-100 µm, for example, in the range of 100-500 µm, such as in the range of 50300 µm, for example, in the range of 75-300 µm, such as in the range of 75-200 µm, for example, in the interval 75-150 µm, as in the range of 75-120 µm.

In yet another embodiment of the present invention, the porous material in at least one reactive pad and / or in the developer pad may be selected from a group of materials comprising a suitable pore size such as at most 500 µm, for example , at a maximum of 200 µm, such as a maximum of 150 µm, for example, at a maximum of 100 µm, such as a maximum of 75 µm.

Preferably, the porous materials used in the at least one reactive pad and / or the developer pad may be the same in at least 2 pads, such as at least 3 of the pads, for example 4 of the pads, such as at least 5 of the pads.

In accordance with the above porous material, it may be desirable to provide a device for detecting an analyte in a rapid assay. In one embodiment of the present invention the test time at about 20 ° C may be less than 20 minutes, such as less than 18 minutes, for example, less than 15 minutes, such as less than 12 minutes, for example, less than 10 minutes, such as less than 8 minutes, for example, less than 5 minutes, such as less than 3 minutes, for example, less than 2 minutes, such as in the range of 1 to 25 minutes, for example in the range of 2-25 minutes, such as in the range of 5 to 20 minutes, for example in the range of 8-18 minutes, such as in the range of 10 to 15 minutes, for example in the range of 11-14 minutes, such as in the interval of 1213 minutes.

The solid support

The device according to the present invention may be supported by a solid support. In the present context, the term "solid support" refers to a material that has no influence on migration in the reaction of the liquid milk sample or in the reagent (s) or agents capable of increasing the speed of the reaction. The solid support provides a stabilizing base for the test device and provides sufficient strength to maintain the desired physical form and substantially does not interfere with the production of a detectable signal.

In one embodiment of the present invention, the solid support material is selected from the group consisting of tubes, polymer beads, nitrocellulose strips, membranes, filters, plastic sheets and the like.

Naturally, synthetic and naturally occurring materials that are synthetically modified can be used as the solid phase material. Such materials include polysaccharides, for example, cellulosic materials such as paper and cellulosic derivatives, such as cellulose acetate and nitrocellulose, inorganic silica materials, such as, for example, non-activated alumina, diatomaceous earth, MgSO4 or other inorganic materials. finely divided uniformly dispersed in a porous polymeric matrix, wherein the matrix may comprise one or more polymers such as homopolymers and copolymers of vinyl chloride, for example, polyvinyl chloride, copolymer of vinyl-propylene chloride, and copolymer of vinyl-vinyl acetate, fabric, of natural origin (for example, cotton) and synthetic (for example, nylon), porous gels, such as silica gel, agarose, dextran, and gelatin, polymeric films, such as polyacrylamine, and Similar.

 In one embodiment of the present invention, the solid support can be omitted from the dry stick test device. In this case, the dry stick test device comprises at least one test pad and one developer pad. When an analyte is determined using a dry stick test device without a solid support, the sample is applied to the dry stick test device on a surface and the detectable signal can be detected on the same surface, and thus any possible precipitation of the components of the milk sample on the surface where the detectable seral is to be detected is limited or eliminated.

The reactive pillow

In the present context the term "reactive pad" refers to one or more pads comprising a reagent or a combination of reagents. The reagent or reagent combination may be impregnated in the reagent pad so that the reagent or reagent combination is immobilized when it is in the dry state and is mobile when it is in the wet state.

In the present context of the present invention the term "reagent" refers to the chemical that reacts with or participates in or is necessary for the determination of an analyte, a derivative of said analyte or an indicator compound for said analyte to provide a Seral detectable. A similar definition of the combination of reagents can be provided which more specifically refers to 2 or more reagents, such as 3 or more reagents, for example, 4 or more reagents, such as 5 or more reagents, for example, 6 or more reagents

In one embodiment of the present invention the dry stick test device comprises at least 2 reactive pads, such as at least 3 reactive pads, for example, at least 4 reactive pads, such as at least 5 reactive pads, for example, at minus 6 reactive pads. In this embodiment, the reagents that react with or participate in or are necessary for the determination of an analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal can be introduced into different reactive pads. This can improve the stability, storage and applicability properties of the dry swab device because unsupported compounds may be included in the different reagent pads of the dry swab device.

The revealing pillow

In the present context, the term "developer pad" refers to a pad capable of regulating the medium and conditions for the milk sample comprising the analyte to a medium that facilitates the determination of the analyte, a derivative of said analyte or a indicator compound for said analyte.

In one embodiment of the present invention, the developer pad comprises one or more control compounds capable of increasing the reaction rate between the analyte, a derivative of said analyte or an indicator compound for said analyte present in the milk sample and the (the) reagent (s). In one embodiment of the present invention the control agent is an acid.

In yet another embodiment of the present invention, the developer pad is in contact with at least one reactive pad by a substantially complete overlap, by a partial overlap or by the placement adjacent to at least one reactive pad. In one embodiment of the present invention, the developer pad is superimposed on at least one reactive pad by at least 5%, such as at least 10%, for example, at least 25%, such as at least 50%, for example, at least 75%, such as at least 80%, for example, at least 90%, such as at least 95%. In the present context the term "substantially complete overlap" refers to two separate pads (the developer pad and the at least one reactive pad) placed one on top of the other. In the present context the term "partial overlap" refers to two separate pads (the developer pad and the at least one reactive pad) that overlap with only part of the pad (s). A partial overlap of 100% refers to a complete overlap and a 5% deviation of 100% of complete overlap refers to a substantially complete overlay.

In one embodiment of the present invention the developer pad and the at least one reactive pad (s) are placed adjacent to each other. This means that the pads are placed in contact with each other (touching each other). An overlap of 0% (but in contact) refers to the term "adjacent placed", in addition, an overlap of less than 5% is considered within the term of "adjacent placed", such as a maximum overlap of 4%, by For example, a superposition of a maximum of 3%, such as a superposition of a maximum of 2% or, for example, an overlap of a maximum of 1%.

Control compound

A control compound is immobilized on the developer pad. In the present context the term "control compound" refers to a substance that functions as a propellant or a fuel in the specific test for the determination of the analyte, a derivative of said analyte or an indicator compound for said analyte. The control compound may also be the chemical substance responsible for the precipitation of the sample components or the chemical compound that causes the milk sample components not to precipitate. In one embodiment of the present invention, the control compound can be separated from at least one of the reagents to improve the stability of the dry stick test device.

In yet another embodiment of the present invention the control compound is an acidic compound. The control compound is an acidic compound capable of providing a pH value of the sample in the dry stick test device, when in a wet state, below pH 6, such as below pH 5, for example, below pH 4, such as below pH 3, for example, below pH 2, such as below pH 1, for example, below pH 0, such as in the range of pH 0-6 , for example, in the range of pH 0-5, such as in the range of pH 0-4, for example, in the range of pH 0-3, such as in the range of pH 0-2, for example, in the range of pH 0-1, such as in the range of pH 1-6, for example, in the range of pH 2-6, such as in the range of pH 3-6, for example, in the range of pH 4-6, such as in the range of pH 5-6.

The anaIitos to be determined

A device or method based on the foregoing principles can be used to determine a wide variety of analytes by the selection of suitable coloring compounds known to the person with experience in the industry, and the invention need not be limited to the examples mentioned herein. .

In one embodiment of the present invention, the analytes to be tested may be selected from the group consisting of a protein, a fat, a carbohydrate, an antibiotic, a steroid, such as hormones, a vitamin, a chemical compound, a hapten. , a cell, such as a bacterium or such as leukocytes, an antibody, a drug of abuse and blood.

In one embodiment of the present invention, the analyte is a chemical compound and the chemical compound can be selected from the group consisting of urea, triglyceride and ketone bodies, such as acetoacetate, betahydroxybutyrate (BHB), acetone, ascorbic acid, nitrates, urobilinogen, cholesterol, and steroids such as pregnenolone, progesterone, testosterone, dihydrotestosterone, estrone, estradiol, cortisol, cortisone, aldosterone, corticosterone, androstenedione, 17a-OH-pregnenolone, 17a-OH- progesterone, 11-deoxy-, corticosterone, 11-deoxycortisol and dehydroepiandrosterone, luteinizing hormone or human chorionic gonadotropin.

The device and method according to the present invention may also be suitable when the analyte is a carbohydrate and the carbohydrate can be selected from the group consisting of a monosaccharide, such as glucose or galactose, and a disaccharide, such as lactose.

In one embodiment of the present invention the dry stick test device is used for the determination of urea in a milk sample. The dry stick test device may optionally comprise a solid support and at least 2 pads, said at least 2 pads comprise (i) at least one reactive pad comprising o-phthalaldehyde or a derivative thereof, a coloring compound and a detergent, and (ii) a developer pad comprising at least one acid, wherein a developer pad may be located downstream of the at least one reactive pad. In this embodiment, the acidic compound is capable of providing a pH value of the sample in the dry stick test device, when in a wet state below pH 6, such as below pH 5, for example, below of pH 4, such as below pH 3, for example, below pH 2, such as below pH 1, for example, below pH 0, such as in the range of pH 0-6, for for example, in the range of pH 1-5, such as in the range of pH 1-4, for example, in the range of pH 1-3, such as in the range of pH 1-2, for example, in the pH range 2-6, such as in the range of pH 3-6, for example, in the range of pH 4-6, such as in the range of pH 5-6. Preferably, the at least one reactive pad is in contact with the developer pad by substantially complete overlap, by partial overlap or by adjacent placement. It is further preferred that the developer pad can be located between the solid support and the at least one reactive pad.

The sample of Ieche to analyze

To moisten the porous material used in the developer pad and / or in the at least one reactive pad to allow migration, the liquid milk sample is liquid milk applied. In addition, it is preferred that a minimum number of handling steps of the liquid milk sample be necessary before applying it to the dry stick test device. In the present context, the term "handling steps" refers to any type of pretreatment of the liquid milk sample before or after it has been applied to the test device. This pretreatment comprises separation, filtration, dilution, distillation, concentration, inactivation of interfering compounds, centrifugation, heating, fixation, reagent addition, or chemical treatment.

In one embodiment of the present invention, the milk sample may be collected from a mammal, preferably the mammal is selected from the group consisting of herd animals, cows, camels, buffalo, pigs, horses, deer, lamb, goats, pets, Dogs, cats and humans.

In one embodiment of the present invention, the sample is milk.

In a preferred embodiment of the present invention a dry stick test device is provided for the determination of an analyte in a milk sample by means of a chemical test. The device comprises:

(i)

 optionally a solid support,

(ii)

 at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state,

(iii) a developer pad that is located in contact with the at least one reactive pad, optionally between the solid support and the at least one reactive pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent reacts with the analyte to provide a detectable signal,

wherein the at least one test pad is capable of providing a pH value of the milk sample of 6 or above 6, and the control compound present in the developer pad is capable of providing a pH value of the sample of milk below 6, where the at least one reagent pad and the developer pad are arranged to prevent precipitation of the milk sample component (s) on the upper face of the device, where the sample is applied in the upper face of the device and the detectable signal is obtained from the upper face of the device and where the upper face of the device is related to the surface where the sample is initially contacted with the at least one reactive pad. In this embodiment, the acidic compound is capable of providing a pH value of the sample in the dry stick test device when it is in a wet state in the range of pH 1-5, such as in the range of pH 1-4 , for example, in the range of pH 1-3, such as in the range of pH 1-2, for example, in the range of pH 2-5, such as in the range of pH 3-5, for example, in the pH range 4-5, such as in the pH range 5-6. Preferably, the at least one reactive pad is in contact with the developer pad by substantially complete overlap, by partial overlap or by adjacent placement. It is further preferred that the developer pad can be located between the solid support and the at least one reactive pad.

The auxiliary compound

Due to the complexity of the liquid milk samples to be analyzed in the present invention it may occasionally be an advantage to use an auxiliary compound to improve the flow and adsorption of the liquid milk sample in the regulating pad and / or in the or more reactive pad (s) and to provide a rapid, consistent and uniform release of the reagent (s) and agents capable of increasing the reaction rate. The auxiliary compound can be supplied to the device by a) adding it to the at least one reactive pad (s) and / or regulating pad alone or together with the liquid milk sample, b) incorporating the auxiliary compound into at least one of the reagent pad (s) and / or the regulation pad, or c) a combination of these.

In one embodiment of the present invention, the auxiliary compound is scratched into the dry swab device before the liquid milk sample is plowed. Preferably, the auxiliary compound is a liquid.

In another preferred embodiment of the present invention, the auxiliary compound and the liquid milk sample are scratched into the layered dry stick device. In the present context, the term "layers" refers to the division of the volume of the auxiliary compound and the volume of the liquid milk sample, and then the auxiliary compound and the liquid milk sample are scratched to the first zone one after other. In this case, the auxiliary compound can be added as a liquid as well as a solid compound. In one embodiment of the present invention, the auxiliary compound and the liquid milk sample are divided into at least 2 volumes where each provides 4 alternate layers of the auxiliary compound and the liquid milk sample, for example, the auxiliary compound and the sample of liquid milk are divided into at least 3 volumes where each provides 6 alternate layers of the auxiliary compound and the liquid sample, such as the auxiliary compound and the liquid milk sample is divided into at least 4 volumes where each provides 8 alternate layers of the auxiliary compound and the liquid milk sample, for example, the auxiliary compound and the liquid milk sample are divided into at least 6 volumes where each provides 12 alternate layers of the auxiliary compound and the liquid milk sample, such as the compound auxiliary and the liquid milk sample are divided into at least 8 volumes where each provides 16 alternate layers of the auxiliary compound and the liquid milk sample For example, the auxiliary compound and the liquid milk sample are divided into at least 10 volumes where each provides 20 alternate layers of the auxiliary compound and the liquid milk sample, such as the auxiliary compound and the liquid milk sample. They divide into at least 20 volumes where each provides 40 alternate layers of the auxiliary compound and the liquid milk sample.

In even one embodiment of the present invention the auxiliary compound can be impregnated in at least one reactive pad (s) and / or in the regulating pad.

In another embodiment of the present invention at least one reactive pad and / or the developer pad incorporating at least one auxiliary compound capable of improving the flow of the liquid milk sample.

In yet another embodiment of the present invention the auxiliary compound provides a rapid, consistent and homogeneous release of the reagent (s) in the at least one reactive pad and / or the agent capable of increasing the reaction rate in the pad. revealing In addition, the auxiliary compound provides low affinity for protein binding.

In addition, the auxiliary compound can provide low retention of triglyceride-rich samples and / or decrease the viscosity of the sample.

In one embodiment of the present invention the auxiliary compound contains chemical constituents selected from the group consisting of water, a surfactant, a salt, a metal, a sugar, a protein, a solvent and a lipid.

Preparation of dry sticking

The dry stick device according to the present invention can be prepared by any of the conventional methods provided for the preparation of dry stick devices. In a preferred embodiment the method of providing a dry stick device according to the present invention comprises the steps of:

(i)

providing at least one reactive pad by impregnating a first porous material with an aqueous solution comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when in the wet state,

(ii)

 after that dry the at least one test pad,

(iii) providing a developer pad by impregnating a second porous material with an aqueous solution comprising at least one control compound which, when in a wet state, is capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal,

(iv)

 after that dry the second impregnated porous material

(v)

immobilize the first porous material with the second porous material, optionally on a solid support, to obtain the dry stick device.

In one embodiment of the present invention the at least one reactive pad is located in relation to the developer pad to prevent the precipitation of the sample of the milk component on the upper face of the device. Preferably, the developer pad is located between the solid support and the at least one reactive pad. The milk sample component as described above can be selected from the group consisting of proteins, carbohydrate, fat, cells, or other components present in the sample.

In even one embodiment of the present invention the first porous material can be impregnated with o-phthalaldehyde or a derivative thereof and a coloring compound. In addition, the first porous material can also be impregnated with a detergent.

In another embodiment of the present invention the first porous material may comprise 1, 2 or 3 different porous materials having 3, 2 or 1 impregnated reagent, respectively. Reagents in this mode are selected from o-phthalaldehyde or a derivative thereof, a coloring compound and a detergent.

In one embodiment of the present invention the second porous material can be impregnated with an acid. Said acid may be able to provide a pH value of the sample in the dry stick test device, when it is in a wet state below pH 6, such as below pH 5, for example, below pH 4 , such as below pH 3, for example, below pH 2, such as below pH 1, for example, below pH 0, such as in the range of pH 0-6, for example, in the range of pH 0-5, such as in the range of pH 0-4, for example, in the range of pH 0-3, such as in the range of pH 0-2, for example, in the range of pH 0-1, such as in the range of pH 1-6, for example, in the range of pH 2-6, such as in the range of pH 3-6, for example, in the range of pH 4-6, such as in the pH range 5-6

In one embodiment of the present invention the second porous material may be impregnated with one or more reagents capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state, preferably together With the control compound.

Additional fashion

In one embodiment the dry stick test device according to the present invention is used for the determination of an analyte in a milk sample. Preferably, the analyte is selected from the group consisting of a protein, a fat, a carbohydrate, an antibiotic, a steroid, a vitamin and a chemical compound. Preferably, the chemical compound is selected from the group consisting of urea, triglyceride and ketone bodies, such as acetoacetate, beta-hydroxybutyrate (BOHB), ascorbic acid (citric acid) and acetone. If the analyte is a carbohydrate the carbohydrate can be selected from the group consisting of glucose and lactose.

Urea Determination

As mentioned above, the determination of protein utilization can be an important parameter. As is the case in cattle raising, it is very important that animals (for example, cows) optimally use the protein contained in the feed, since the protein is one of the most expensive components of the feed. The use depends, among others, on the amount of energy and protein simultaneously present in the animal.

The new construction of the dry stick test device according to the present invention can be very useful for the qualitative and quantitative determination of urea in a milk sample. The one or more reactive pad (s) of the dry stick test device may be impregnated with o-phthalaldehyde or a derivative thereof and a coloring compound and optionally a detergent, such as an alkyl polyoxyethylene phenyl ether or a polyoxyethylene alkyl ether.

The o-phthalaldehyde derivative of the present invention refers to a compound that is converted to o-phthalaldehyde after the derivative is dissolved in the milk sample. The derivative includes o-phthalaldehyde glycerol acetal.

The dye compound includes N-1-naphthyl ethylenediamine, N-1-naphthyl-N'-diethylethylenediamine and a salt thereof, such as salts of hydrochloric acid or oxalic acid are included.

The detergent may be a polyoxyethylene alkyl phenyl ether or a polyoxyethylene alkyl ether such as polyoxyethylene (9.5) pt-octylphenylether (HLB: 13.5; trade name: TRITON X-100), polyoxyethylene (40) pt-octylphenylether (HLB: 17.9 ; trade name: TRITON X-405), polyoxyethylene (20) octylphenyleter (HLB: 16.2; trade name: NISSAN NONION HS-220), polyoxyethylene (23) lauryl ether (HLB: 15.3; trade name: Brij35), polyoxyethylene (20) palmitileter (HLB: 15.7; trade name: Brij58), polyoxyethylene (20) lauryl (HLB: 16.2; trade name: NISSAN NONION K-220), polyoxyethylene (20) stearyl (HLB: 15.3; trade name: NISSAN NONION S-220 ), etc.

The polyoxyethylene alkyl phenyl ether or polyoxyethylene alkyl ether of the present invention may have an HLB of 8 or more. In the present context, the term "HLB" refers to the hydrophilic-lipophilic balance of the surfactant. This provides an indication of the hydrophilic portion of the molecule. More hydrophilic groups allow more water solubility since there are more hydrogen bonds there.

In one embodiment of the present invention, the developer pad is impregnated with an acid necessary for urea determination. The acid used can be any type of acid capable of providing and maintaining a pH value of 2.0 or less when dissolved by the liquid sample. Particularly, said acids include 4sulfophthalic acid or an acid polymer.

The respective amount of o-phthalaldehyde or its derivatives, the coloring compound (in the at least one reactive pad) and the acid (in the developer pad) may be the amount necessary for the determination of urea in the specific assay. This means that the amounts are similar to those conventionally used for ophthaldehyde or its derivatives, the coloring compound and the acid in the quantitative determination of urea. Normally, but not limited to the foregoing, the amount of o-phthalaldehyde or its derivatives is in the range sufficient to provide an amount of 0.05M -2M when the o-phthalaldehyde or its derivatives are dissolved in the milk sample. The amount of addition provided in the developer pad may be sufficient to provide and maintain the pH value of the milk sample at 2.0 or less, when the milk sample dissolves in the sample.

The amount of detergent may be sufficient to provide an amount of 0.1-20% (w / v) when the detergent begins to dissolve in the milk sample, such as in an amount of 0.1 -10% (w / v), for example, in an amount of 4-10% (w / v). In one embodiment of the present invention, the amount of detergent, when dissolved in the milk sample, can be calculated based on the capacity of the sample maintained in the dry stick test device.

Other known additives may be added to the dry stick test device that includes stabilizers, such as a surfactant etc. The surfactant can be used to improve the extensibility and solubility of the milk sample and improve the coating properties of the liquid solution (s) after production. In one embodiment of the present invention the amount of a specified surfactant may be the same as the amount conventionally used.

The structure of the dry stick test device of the present invention is not limited except that it must contain o-phthalaldehyde or its derivatives, a coloring compound and a separate acid in at least one reactive pad and a developer pad where the at least one Reactive pad and developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device. The dry stick test device of the present invention can be produced in a manner similar to the production of conventional test pieces for measuring urea or as described herein.

In one embodiment of the present invention the dry stick test device may be provided with a plurality of reactive pads where different reagent (s) are / are comprised in each reactive pad. In addition, an intermediate pad may be provided between the pluralities of reactive pads. In even one embodiment of the present invention the reagents may not all be comprised in at least one reagent pad, but one or more of the reagent (s) may be comprised in the developer pad.

An example of the dry stick test piece is provided in Figure 1. The dry stick test piece comprises a solid support (1) having at one end a reactive section (2). The reactive section (2) comprises a developer pad (3) located on the solid support (1) and on the top of the developer pad (3) is a reactive pad (4). In this example, the milk sample is applied to the test pad

(4) and the reagents (included therein) dissolve and migrate through the reactive pad and the developer pad (4) thus dissolving the acid included therein and the reaction to determine the progress of the urea.

When a predetermined amount of a milk sample is dripped onto the test pad (4) of the dry stick test piece (1), the sample is spread evenly over the entire surface and through the entire test pad (4) . The extended sample reaches the developer pad (4) where the acid comprised in the developer pad (4) dissolves and the reaction proceeds. The determination of urea in the milk sample reacts with o-phthalaldehyde or its derivatives present in the test pad (4) to produce 1,3-dihydroxyisoindrin (DHI). The carbon ion of the resulting DHI reacts with a dyeing compound of the test pad (4) under acidic conditions, provided by the present compound in the developer pad (3), to produce a detectable seral - a color. With the progress of the reaction, the reagents comprised in the reactive pad (4) and the acid comprised substantially dissolve completely and are dispersed in the developer pad (3) thus dissolving the acid comprised therein, and the reactive pad and pad developer together form a detection pad.

It is obvious to those with experience in the industry that the control compound and the construction of the dry stick test device may change based on the concept of the present invention, if a different assay is provided or if another analyte is to be tested.

In addition, it is also obvious to the person with experience in the industry how to select the control compound to optimize the construction of the dry stick test device based on the knowledge provided by the concept of the present invention, specifically, to separate the control compound of the reagents (at least some of them) in different pads and subsequently dispose of these pads to avoid the precipitation of the components of the milk sample, with which the influence of the detected seral can be limited or avoided.

The concept of the present invention will be further illustrated in the following non-limiting figures and examples.

Description of the figures

Fig. 1 shows a possible construction of the dry stick test device according to the present invention where (1) refers to the dry stick test device, (2) refers to the reactive section, (3) refers to the developer pad and (4) refers to the test pad. Fig. 2 shows the dry swab test device where the test pad is placed on top of the developer pad and the dry swab test devices where the developer pad is placed on the reagent pad. The figures show different degrees of precipitation of milk (white spots) on the test pad and the developer pad respectively. Fig. 3 shows an amplification of the upper left reactive pad of Figure 2.

EXAMPLES

EXAMPLE 1: Influence of precipitation on the diffusion of light in the dry basins for urea

Experimental assembly:

The pads comprising a very acidic lower layer (developer pad) and a pad with the dry top layer) are mounted with the developer pad on top or with the reactive pad on top. The milk samples are applied and the distribution of the milk in the pads is described. At the end of the incubation / reaction the pads are scanned and the green color is measured to calculate the influence of the precipitation on the diffusion of the light on the pads.

Preparation of dry sticks for urea:

Dry swabs are used for urea (pads in plastic frames, lot number 20060928-1, produced in accordance with "Production of swabs for UREA ver. 4.0.2") comprising 5x5 mm2 pads. Said pads consisting of two layers glued together, comprising:

one.

a top layer comprising filter paper impregnated with Triton X-405, N, N-diethyl-N'-1-naphthylethylenediamine oxalate, glycerin acetal and ortho-phthaldialdehyde (developer pad) and,

2.

 a bottom layer consisting of woven fabric (nylon / PET) impregnated with 4-sulfophthalic acid (reactive pad).

The glued layers are cut into square pads, 5 by 5 mm2 and placed in plastic frames with the developer pad on top of the reactive pad (mounted inverted) or with the reactive pad on the top of the developer pad (mounted correctly).

Preparation of samples of Ieche:

Two milk samples (hereafter listed # 11 and # 14) were enriched with 500 mg / ml urea.

Performance test of the dry urea sticks mounted correctly and inverted:

Four correctly mounted swabs and four inverted swabs were held by a tape.

8 µl of milk # 11 and 8 µl of milk # 14 were applied in two dry urea sticks inverted separately and in two dried urea sticks mounted correctly separately. After incubation at 25 ° C in 12 minutes and 30 seconds, each dry urea stick was scanned inverted with a Canon ConoScan "2400U scanner.

In dry urea sticks that comprise the correctly mounted pads, the milk spreads easily and freely enters the pad. After incubation the color spreads evenly over the entire surface. In dry urea sticks comprising inverted mounted pads, the 8 µl of milk remains as a small drop, slowly releasing the liquid in the pad. After incubation the constituents of coagulated milk (protein ("cheese") with fat globules) remain on the surface of the pad, forming a white spot that covers approximately 2/3 of the area (See Figures 2 and 3) .

Each of the eight scanned pads (with 300 dots per inch) was measured using the Matlab program, a routine program that uses red, green and blue. The field measured on each dry urea stick constitutes approximately 4x4 mm2 since the edges of the pads were excluded.

The table below shows the green values.

Pad orientation

Green average from Standard deviation of pixels (green color)

Revealing pad above "inverted"

first # 14 sample 213.2 25.6

second # 14

sample 209.7 30.1

first # 11

sample 205.3 35.4

second # 11

sample 194.5 36.6

Reactive pad above "correct"

first # 14 sample 204.3 5.1

second # 14

sample 213.7 8.7

first # 11

sample 206.1 5.8

second # 11

sample 199.4 5.1

ConcIusion:

The above results clearly show that the standard deviation of pixels (green color) is significantly higher (5-6 times) when the pads are oriented with the developer pad up (inverted mounted pads) compared to the pads with the reactive pad up (pads) mounted correctly). The results show that the color produced is not distributed uniformly, which causes false readings of the

10 swab when the pads are mounted upside down and confirms that the milk clots / precipitates significantly influence the test and significantly influence the performance of the dry swab.

References

15 US 4,125,995 JP 10-229023

Claims (11)

1. A dry stick test device for the determination of an analyte in a milk sample by means of a chemical test, said device comprises:

(i)

 optionally a solid support,

(ii)

at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state,

(iii) a developer pad that is located in contact with the at least one reactive pad, optionally between the solid support and the at least one reactive pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent reacts with the analyte to provide a detectable signal, wherein the developer pad is located downstream of the at least one reactive pad wherein the at least one test pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device and where the sample is applied on the upper face of the device and the detectable signal is obtained from the upper face of the device and wherein the control compound is an acid compound capable of providing a pH value of the milk sample below 6 and where the upper face of the device is related with the surface where the sample is initially contacted with the at least one reactive pad.

2.

A device according to any of the preceding claims, wherein the at least one reactive pad comprises o-phthalaldehyde or a derivative thereof, a coloring compound and a detergent.

3.

A device according to any of the preceding claims, wherein the analyte is selected from the group consisting of a protein, a fat, a carbohydrate such as monosaccharides, such as glucose or galactose and disacarides, such as lactose, an antibiotic, a steroid, a vitamin, and a chemical compound such as urea, triglyceride and ketone bodies, such as acetoacetate, beta-hydroxybutyrate (BOHB), citric acid, lactic acid and acetone.

Four.

A dry stick test device for the determination of an analyte in a milk sample by means of a chemical test, said device comprises:

(i)

 optionally a solid support,

(ii)

at least one reactive pad comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when it is in a wet state,

(iii) a developer pad that is located in contact with the at least one reactive pad, optionally between the solid support and the at least one reactive pad, said developer pad comprises at least one control compound capable of providing a condition required for the reagent reacts with the analyte to provide a detectable signal, wherein the developer pad is located downstream of the at least one reactive pad wherein the at least one test pad is capable of providing a pH value of the milk sample of 6 or above 6, and the control compound present in the developer pad is capable of providing a pH value of the sample of milk below 6, where the at least one test pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device, where the sample it is applied to the upper face of the device and the detectable signal is obtained from the upper face of the device and where the upper face of the device is related to the surface where the sample is initially contacted with the at least one reactive pad.

5.

A dry stick test device for the determination of urea in a milk sample, said dry stick test device optionally comprises a solid support and at least 2 pads, said at least 2 pads comprise (i) at least one reactive pad comprising o-phthalaldehyde or a derivative thereof, a coloring compound and a detergent, and (ii) a developer pad comprising at least one acidic compound capable of providing a pH value of the milk sample below 6, in where the at least one test pad and the developer pad are arranged to prevent precipitation of the component (s) of the milk sample on the upper face of the device, where the sample is applied on the upper face of the device and the detectable signal is obtained from the upper face of the device and where the upper face of the device is related to the surface where the sample is initially contacted with the at least one test pad.

6.

A method for the preparation of the dry stick device according to any of claims 1-5, said method comprises the steps of:

(i)

providing at least one reactive pad by impregnating a first porous material with an aqueous solution comprising a reagent capable of reacting with the analyte, a derivative of said analyte or an indicator compound for said analyte to provide a detectable signal when in the wet state,

(ii)

 after that dry the at least one test pad,

(iii) providing a developer pad by impregnating a second porous material with an aqueous solution comprising at least one control compound which, when in a wet state, is capable of providing a condition required for the reagent to react with the analyte to provide a detectable signal,

(iv)

 after that dry the second impregnated porous material, and

(v)

immobilize the first porous material with the second porous material, optionally on a solid support, to obtain the dry stick device.

7.

A method for the determination of an analyte in a milk sample, said method comprises the steps of:

(to)

applying the sample suspected of containing the analyte to a dry stick test device according to any of claims 1-6,

(b)

allow the sample to migrate into the at least one reagent pad and the developer pad and mobilize the at least one reagent and the at least one control compound, and

(C)

allow the at least one reagent and the analyte, the derivative of said analyte or the indicator compound for said analyte to react and provide a detectable signal

8.

A method according to claim 7, wherein the analyte is selected from a group consisting of a protein, a fat, a carbohydrate such as glucose and lactose, an antibiotic, a steroid, a vitamin, a chemical compound such as urea, triglyceride. and ketone bodies, such as acetoacetate, beta-hydroxybutyrate (BOHB) and acetone.

9.

Use of a device according to any of claims 1-5 for the determination of an analyte in a milk sample.

10.

Use according to claim 9, wherein the analyte is selected from the group consisting of a protein, a fat, a carbohydrate, an antibiotic, a steroid, a vitamin and a chemical compound.

eleven.

Use according to claim 10, wherein the chemical compound is selected from the group consisting of urea, triglyceride and ketone bodies, such as acetoacetate, beta-hydroxybutyrate (BOHB) and acetone.