JPS5952981B2 - Electrochemical analysis method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to charge transfer reactions (
The present invention relates to an electrochemical measurement system for performing, measuring and classifying charge transfer reactions.

The system includes a novel electrode adapted to simultaneously measure at least two electrolytic currents relative to a reference potential on at least two electrodes. In a preferred embodiment, the electrode is comprised of a hollow cylindrical body formed of an electrically insulating material. The electrode is open at at least one end and has a generally smooth cylindrical inner surface. Multiple electrically isolated active electrode segments (Segnlent)
are contained on the inner surface and their active surfaces are in substantially flush contact with the generally smooth cylindrical inner surface. To complete the electrochemical measurement system, a stirring device for generating a relatively high degree of mixing adjacent to the electrode active surface, a device for charging the liquid sample into the cell, and an electrically isolated active There are devices that connect at least two of the electrode segments to different potentials. The sample to be tested for use is placed in the container and stirring is started. One of the electrically isolated active electrode segments is held at a potential to which the selected substance of interest and also one or more interfering substances respond, while the other electrode segment is held at a potential to which only the interfering substance responds. Ru. The presence of the substance of interest is determined by subtracting the signals from one and the other electrode segments, and its amount is determined by integrating the signal difference. Various electrochemical systems are known for detecting and/or measuring the presence of various substances of interest in sample solutions suspected of containing selected substances;
and they have found utility in a variety of environmental, medical, and industrial applications.

Although such systems are generally used for analysis for metal ions of interest, they are also used for analysis of nonmetals such as cyanide ions, sulfur dioxide, and halogens, as well as certain organic substances. It also exists for detection. One mode of prior art electrochemical analysis uses a gravimetric method in which the deposit formed by electrical action is weighed on an analytical balance.

Gravimetric methods 1 are prone to weighing errors, require skilled technicians, and are relatively time consuming and insensitive. Another mode of electrochemical analysis in the prior art uses ion-selective electrodes.

A number of ion-monoselective electrodes have been devised for testing various ions of interest and are considered reliable and easy to use. However, many substances of interest in the environmental, industrial and medical fields cannot be measured by ion-monoselective electrodes. Additionally, ion monoselective electrodes respond logarithmically and are therefore generally not sensitive enough to measure concentrations below about 10-5 to 10-6 molar. Polarographic analysis based on the current-voltage curve obtained with a dropping mercury electrode has advantages over ion-monoselective electrodes in terms of sensitivity in dilute solutions. The characteristics and conditions of a classical dripping mercury polarographic electrolyzer are a dripping mercury electrode, ie, mercury droplets are periodically ejected into the solution from a fine-bore capillary tube under a mercury driving head. However, although the above characteristics have made it possible to incorporate very useful polarographic methods into research, there is a more general use of classical polarographic electrolyzers, i.e. in ordinary analytical systems, especially in industrial processes. Its attributes are diluted or lost when used as a device for monitoring and regulating the environment, or as a field test in medical and environmental applications. Additionally, the periodic growth and fall characteristics of the mercury droplets cause oscillations in the current-voltage curves obtained using such a bath. Other problems with the dropping mercury electrode, which essentially limit the use of the bath to laboratory and testing purposes, limit the build-up of the capacitor current as new mercury drops are formed in the capillary tube, as well as the sensitivity of the electrode. the limited surface area of the drop. Furthermore, the formation of tiny mercury droplets is affected by numerous accidental factors, such as mechanical vibrations,
It is a delicate process that can be influenced by the slope of the capillary tube and the pulsation of the test solution into the capillary entrance between their drops, etc. In this regard, the drop reproducibility in terms of drop line and amount of mercury per drop must always be practically perfect to allow a proper evaluation of the polarogram. Yet another type of prior art electrochemical measurement system is a technique called coulometric stripping voltammetry.

Coulometric stripping voltammetry consists of electrolytically depositing an electroactive substance of interest onto or into an indicating or working electrode and then electrolytically dissolving or stripping the deposited substance back into solution. This is a two-step method consisting of: In anode stripping voltammetry, the substance to be measured is plated onto an electrode by applying a negative potential for an extended period of time, and then the material is stripped from the electrode by applying a positive potential for a relatively short period of time. The order or potential at which the elements of the material are stripped from the electrode provides a qualitative analysis of the material, and the amount of current provides a quantitative analysis. Anodic stripping voltammetry offers the advantages of enhanced sensitivity, clarity and reproducibility compared to classical polarographic analysis obtained using dropping mercury electrodes. For example, thin film mercury/graphite composite electrodes have been used in anodedic stripping voltammetry systems for analysis of sub-nanogram metals. For example, 46
RapidSub-NanOgram Simulta
neOusAnalysisOfZn. Cd. Pb. C
u. BiandTi-Trace Substances
inEnvirOnmentalHealth Layer Miss Ichiriichi University, Dr. D. Hemphill. Wayne R in Ed; pages 396-406, (1971)
．． MatsOn. ReginaldM. Griffin
, and GeOrgeB. See Schreiber's report. For example, the anode stripping voltammetry 1 taught by MatsOn et al.
Although electrochemical solution analysis using synthetic mercury/graphite electrodes provides sub-nanogram sensitivity, the ability to rapidly and reliably partition and measure selected substances at picogram levels remains limited. This is generally not possible using existing electrochemical measurement techniques. Also, many metals interact with the electrodes to form alloys or amalgams. In this way, anodetics and cathodic stripping voltammetry are limited to the detection of relatively small classes of metals and non-metals. clearly,
The ability to act at such low concentrations and across a wide range of species would have major commercial utility in environmental, medical, and industrial applications. 'Thus, one object of the present invention is to provide a new and improved system, method, and apparatus that overcomes the problems and limitations of the prior art discussed above.

Another main object of the invention is a new and improved method for electrochemically analyzing a sample in order to qualitatively and/or quantitatively determine the presence of selected substances in the sample. and equipment.

Yet another object of the invention is to provide an electrochemical measurement system of the type described above which can operate rapidly and reliably with sensitivity on the picogram level.

A more specific object is to provide new and improved electrodes for use in electrochemical systems.

To achieve the foregoing objects as well as others, an electrochemical measurement system is provided that provides for the measurement and partitioning of charge transfer reactions of selected substances in a sample solution.

The system includes a novel electrode adapted to simultaneously measure two electrolytic currents relative to a reference potential on at least two electrodes. In a preferred embodiment, the electrode comprises a hollow cylindrical body of electrically insulating material. The electrode is open at at least one end and has a generally smooth cylindrical inner surface. A plurality of electrically separated active electrode segments are housed on the inner surface of the electrode with their active surfaces substantially flush against the generally smooth cylindrical inner surface. To complete the electrochemical measurement system, there is a stirring device adjacent to the electrode active surface to provide a relatively high degree of mixing, a separate station for charging the liquid sample to the electrolytic cell, and at least two electrical A device is provided for connecting the divided active electrode segments to different potentials. In use, the sample to be tested is loaded into the electrolytic cell and stirring is started. One of the electrically separated active electrode segments is held at a potential to which the selected substance of interest and also one or more interferent substances respond, while the other electrode segment is held at a potential to which only the interferent substance responds. Retained. The presence of the substance of interest is determined by subtracting the signals from one and the other electrode segment, and its amount is determined by integrating the signal difference. Further objects of the present invention will be partly apparent and will become further partly apparent from the following description.

The invention thus comprises a device having a structure, a combination of elements and an arrangement of parts, and a method consisting of a number of stages and the relationship of one or more such stages to each other; All are exemplified in the following detailed description and scope of application as indicated in the claims. BRIEF DESCRIPTION OF THE DRAWINGS In order to fully understand the nature and objects of the invention, the invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a perspective front view of a preferred embodiment of an electrochemical measuring device according to the present invention, and FIG. 2 is a partially sectional front view of a preferred embodiment of the electrolytic cell of the device of FIG. 3 is an end view showing a cross section of the sample solution stirring member of the apparatus shown in FIG. 1, and FIG. 4 is a fragmentary plan view showing a cross section of a preferred embodiment of the sensing electrode element of the apparatus shown in FIG. 5 is a diagram of the flow detector element of the device of FIG. 1, FIG. 6 is a plot diagram of the electrical and pneumatic regulation and actuation of the device of FIG. 1, and FIG. 8 and 9 are plots showing the current in microamperes, μA, versus the potential in volts relative to a standard silver/silver halide reference electrode obtained in accordance with the present invention, and FIGS. FIG. 3 is a perspective front view of another embodiment of an electrolytic cell according to the present invention.

The invention is based on measuring the electrochemical reactions of selected substances in solution under controlled potential conditions.

dissolving the electroactive material in a solvent to form a reagent or electrolyte, as is well known in the art;
When a current is passed through the electrolyte between an anode and a cathode placed within it, the positive ions are attracted to the negatively charged cathode and their charge is neutralized, while the negative ions are It will move towards the anode and there will be a discharge. The potential at which such electrochemical reactions occur will vary depending on the particular materials involved. For example, consider an aqueous solution containing both iron and copper ions. Iron usually exhibits a valence of 2 or 3, while copper usually exhibits a valence of 1 or 2. The potential at which ferric ions (Fe+3) in a solution are reduced to ferrous ions (Fe+2) is constant at a given temperature. Similarly, cupric ions (Cu+2) in solution
The potential at which Cu+1 is reduced to cuprous ions (Cu+1) is also constant at a given temperature and is different from the potential at which the reduction of ferric ions to ferrous ions occurs.

The potentials at which such reactions occur are approximately indicated by standard or official potential tables). The absolute value of the potential of the ions in the solution is not uncertain. However, the electrochemical reactions for specific substances are based on standard reference pairs, e.g. H2/
It is described in terms of potential relative to H+. Potential magnitude is a measure of the potential that must be applied relative to a standard reference electrode to cause charge transfer to occur. The potential at which such a reaction occurs is called the "charge transfer potential." If we specify an arbitrary value of zero for hydrogen, the potential E of the electrochemical reaction can be written according to the following equation: (where n is the Farade number, Ap and AR are the activities of the reactants produced and x and y are the corresponding coefficients of the electrochemical reaction).

In this way its potential E. is the standard potential associated with a particular reaction. E is the potential applied to drive the reaction on the reactants or products according to the equilibrium conditions described by equation (1). Under conditions where the applied E is large enough to bring the reaction to virtually complete equilibrium, the induced current will be proportional to the concentration of reactants in solution. However, background noise precludes direct measurement of most sample solutions and often precludes direct measurement of very dilute solutions.
[As used herein, the term “background noise” refers to the presence of other electrically active substances in solution (
the major interfering factors such as ions (which respond to the same potential as the ions in question due to their electroactivity in that solution), and the boundary layer of quiescent solution adjacent to the active surface of the electrode. A signal due to the capacitance of the electrode in the solution due to the presence of , a signal due to the body of the solution, an inherent induced signal,
Refers to both major non-Faladic interference factors such as electrode stabilization signals and the like. An aspect and advantage of the present invention is the elimination and/or cancellation of background noise through a combination of electrochemical manipulation and electrode geometry. The features and advantages of the invention will be better understood from the following description, which details one preferred embodiment of the invention, which describes an electrochemical test system for measuring iron content in serum or blood. Will.

However, it will be appreciated that the system of the present invention can be advantageously used for detecting the presence and determining the concentration of various other substances of interest in sample solutions. Referring to FIG. 1, there is shown an electrochemical measurement apparatus, generally designated 10, including a base 11. As shown in FIG.

The cabinet 13 is mounted on the foundation 11 by means of upright supports 12.
is attached, and its front side serves as the control panel 14. The panel includes a display board 16, operation buttons including a standby button 17, and "゜AutoBlank (AutoOblank).
k)゛Adjustment button 18,゜゜Auto blank set (
Various adjustments are provided including an AutoOblankset button 19 and a scale adjustment knob 20.
Further located on the control panel 14 are an open/close button 22 and a flow rate indicator 23 suitably displayed to indicate that the previous sample has been flushed out and a new test may be started. Furthermore, there is a start button 24 and an "in operation" indicator 25 on the control panel.It is convenient and preferable that these controls be performed by a combination of a push button and an indicator light, and this is the case in the actual device). A typical button and light combination is used. Mounted below the cabinet 13 is an electrolytic cell assembly 27, shown schematically here but shown in detail in FIG. 2. Basics 1
Two containers 28 and 29 are placed on top of the
They are suitably connected to the electrolyzer block by plastic tubing or the like. Vessel 28 receives the cell contents which are flushed out at the end of each test, and vessel 29 provides a source of fresh cell fluid or electrolyte. FIG. 2 shows the electrolytic cell assembly of the apparatus of FIG. 1, which generally consists of a cell hook 33 and a sensing electrode 34 mounted thereon.

The tank block 33 comprises a suitable mounting member, such as a plastic block block having a single screw 35 or other mounting member at the upper end. A vertical channel or cylindrical hole 36 passes through the bath block and into the interior of the sensing electrode 34. There are two channels, the first of which is an artificial channel 38 for receiving the sample to be tested.
For example, a pipette inserted into the channel 38 (
(not shown), the second of which is an outlet channel 39 for bath liquid.

The tank block 33 is formed from a liquid-impermeable, rigid, electrically insulating, and chemically inert material such as unplasticized polyvinyl chloride, polytetrafluoroethylene fluorocarbon resin, or the like. The bottom of the channel 36 is recessed to receive the sensing electrode 34.

The sensitive electrode 34 is in the form of a hollow cylinder, the inner surface of the electrode and the inner surface of the channel 36 being flush and as smooth as possible to minimize the amount of material trapped between them. It is designed to become. In practice, the electrodes are permanently attached to the tank hook by suitable means, such as epoxy resin, and the inner surface of the joint between the two is machined smooth. Sensing electrode 34
At the bottom of the is a hermetic connection 46, which may for example be in the form of a cast-molded plastic plug to the sensing electrode 34, and a threaded connection 35a for connecting a pipe or hose to it. and a flow path 49 extending therethrough. A continuous flow path is thus formed, with the electrolyte or other cell contents flowing through the flow path 49 and the outlet 39 of the cell block above the electrodes.
It can be discharged by flowing out through. As previously mentioned, important features and advantages of the present invention are that the electrical signals representative of the charge transfer electrolytic reactions of the selected substance of interest and the electrical signals derived from the total sample solution, interfering substances, and other background noise; It is the ability to distinguish between

This feature and advantage is enabled in part by the structure of sensing electrode 34. Sensing electrode 34 comprises a generally cylindrical body of block epoxy with a plurality of active electrode segments mounted therein. The electrode body is made of an electrically insulating material such as a polymeric material,
Alternatively, the active electrode segment may consist of a suitable electrode substrate such as graphite, pyrolytic graphite or platinum, or alternatively may consist of a coating of active electrode material such as mercury or gold. . In practice at least two electrically separated electrode areas are used, for example in the form of a ring or band of the active electrode surface on the interior of the hollow electrode body. The segments are separated by electrically insulating bands on the interior of the electrode. Such electrodes can be formed by holding segments of active electrode material in a ring shape in the desired position and molding the ring with an electrically insulating material such as epoxy resin to form a cylinder. . Sensing electrode 34 is shown in more detail in FIG. For ease of illustration, the sensitive electrode 34 is shown as consisting of two active test electrode segments, a counter or powered electrode segment and a reference electrode segment: a first active test electrode segment 42, a second active test electrode segment 42, and a reference electrode segment. an active test electrode segment 43, a third counter electrode segment 44 and a reference electrode segment 45. First, second and third active electrode segments 42, 43 and 44 are formed from a suitable electrode material such as graphite, while reference electrode segment 45 is formed from silver, palladium or the like. Electrode segments 42, 43, 44 and 45
each consists of a cylindrical ring embedded into a cylindrical electrode body 41. The electrode segments are separated by narrow gaps so as to be electrically insulated from each other, and they are connected to the inner surface of the electrode body 41 so that the inner surface of all electrodes 34 is as smooth as possible. The surfaces are mounted in substantially the same plane. Electrical connections (not shown in FIG. 4) are provided to each electrode segment and are shown in FIG. It is suitably connected to the device by four conductive wires, each of which ends in a four-legged plug, such as shown in FIG. It will be clear that the electrode may have additional active electrode segments. Electrode 3
A stirring device 50 is disposed within the chamber 4.

The stirring device 50 is mounted by a rod 51 so as to rotate within the electrode body. The stirring device 50 and the rod 51 are made of electrically insulating and chemically inert material;
For example, it is made of molded resin. The lower end of the stirrer 50 is slightly wedge-shaped or conical and generally snug within the electrode body. Radial grooves 5, 2, which are better seen in FIG. 3, run along the surface of the stirring device 50. When rotated in the direction indicated by arrow 54, groove 52
is in close contact with the active surfaces of electrode segments 42, 43, 44 and 45 to create a high degree of mixing or turbulence, thereby minimizing the thickness of the boundary layer of the quiescent solution adjacent to the active surfaces of the electrode segments. , while mass transfer to the electrode surface is maximized.
In use, the open/close button 22 is first actuated.

Typically, the device will be left running overnight in standby mode and will be shut down if it is left unused for more than a week. The device may be calibrated to be more careful at the start of each week or at the start of each day. This correction is performed by first placing the correction button in an operating position so as to standardize the electronic mechanism as described below. A blank sample of reagent is run first. Next, correction is performed by operating the auto blank button 19. Next, a standard sample with a known ion concentration is introduced into the tank 27, and the device is activated to perform one step. After the correction knob 20 is adjusted so that the reading in the display panel 16 corresponds to the known amount of ions in the standard correction sample, a plastic tube or pipe 40 (not shown in FIG. ) connects the tank assembly 27 to the apparatus.

Along the tube 40 and preferably at selected points within the cabinet 13, there are flow detectors shown schematically in FIG. An emitter 55 or other light source is positioned near the window at a point along tube 40. The window may be a transparent insert, or the tube itself may be transparent. On the opposite side of the emitter 55, ie on the opposite side of the tube 40, a detector 56 is located adjacent to a similar window. If tube 40 is empty or filled with gas,
The light beam 57 from the emitter is highly diffused. When tube 40 is filled with a liquid, such as a sliding electrolyte, flowing through the tube, the liquid acts as a lens and increases the sharpness of the focus of light beam 57. Detector 56 is tube 4
is adjusted to a threshold such that the presence of liquid within 0 and the length of time such liquid is present can be determined. A signal from detector 56 indicates that there has been a flow of liquid through tube 40 for a sufficient period of time to complete the flushing of the electrolyte so that the sample is removed therein after one test. used to. For each test, electrolytic cell 27 is repeatedly filled with electrolyte and the cell agitator is operated constantly and continuously to keep the cell contents uniformly mixed.

A known amount of test sample is then pipetted into the electrolytic cell. An operating indicator 25 is illuminated to indicate that a test is being conducted. In a preferred embodiment of the invention, the display is a digital display that counts from zero to micrograms per 100 ml of serum (μg%). The test count is complete when the digital display stops. After a defined waiting time, the sliding electrolyte containing the sample is flushed into the container 28 and fresh electrolyte is replenished into the cell from the container 29. At the start of the test, the test start instruction button 24 lights up again, and the device can be used for the next sample. FIG. 6 shows a block diagram of the electrical and fluid flow control for the above-described device. A cell 27, such as the electrolytic cell of FIG. 1, is connected so that reagents or electrolytes are passed therethrough in individual analytical quantities. The pump 60 connects the reagent container 6 through a flow path 61.
Pump air to 2. Reagent valve 63 regulates the flow of reagent to reservoir 27 . Referring to FIG. 2, the reagents flow down into channel 49 and into and through reservoir 27. Referring to FIG. Another fluid flow path 65 is arranged to convey reagents or other fluids from the reservoir 27 through an optical sensor 68, such as the sensor shown in FIG. Channel 65 thus carries the liquid to drain container 69. Vacuum line 70 returns to pump 60. The flow of liquid through the tank 27 thus enters the bottom of the tank and exits through the outlet 39 located above the tank. Preferably, the inlet channel 38 in the reservoir 27 is positioned slightly above the outlet channel 39 so that liquid normally exits through the channel 39 rather than the channel 38. To analyze a sample, the sample is dissolved in a solvent to form an electrolyte or reagent.

For example, to test iron in blood or serum, a small sample of blood or serum, typically 5 to 100 microliters, releases the iron from binding with the serum and removes the iron from most common interferences. Added to an electrolyte or chemical reagent to separate the transfer potential of the element copper. If total iron binding capacity is to be determined, the serum is first completely saturated with iron by mixing it with an iron-containing ion exchange resin.

Preferably, the serum treatment electrolyte or reagent that liberates iron for testing is strong hydrochloric acid, e.g.
/2 to about 81/2 normal, preferably about 7 normal, with strong hydrochloric acid.

Although methanol and ethanol have been found to be almost as effective as propanol and isopropanol, they have the disadvantages of being more expensive, more volatile, and therefore more difficult to handle. Higher alcohols such as butanol can also be used, but they are less compatible with strong hydrochloric acid. Other substances such as acetonitrile and acetone can be used, but they are not satisfactory, partly due to insufficient performance and partly due to their price, volatility, toxicity, etc. It's not possible. The device is calibrated according to the selected concentration of hydrochloric acid. For the electrochemical analysis of iron in blood or serum, as an electrolyte or reagent to liberate iron from its binding with serum and to separate the transfer potential of iron and its most common interfering substance, copper. The use of strong hydrochloric acid in a lower alcohol is considered novel.

Instead of hydrochloric acid, other compounds with a high content of chlorine or halogen may be used, but it has been found that these other compounds are not completely satisfactory.

For example, lithium chloride is a more expensive source of chloride ions, but also tends to precipitate at least a portion of serum. Hydrogen bromide is another source of halogen ions, but it is also expensive, significantly more difficult to work with, and corrosive. Approximately 200 p of silver reference electrode segment 45 is in the reagent or electrolyte.
It contains very small amounts of silver ions in the pm range.

The reference potential is the silver ion potential maintained by reference electrode segment 45. The reagent or electrolyte therefore preferably contains 7N HCl in propanol with 200 ppm silver ions; such reagent or electrolyte liberates iron from the serum or iron-binding components so that the iron is electrochemically It also enables separation of the charge transfer potentials of iron and copper, and provides reproducible results for serum iron analysis by electrochemical measurement with microliter sample volumes. A prepared sample consisting of the serum to be tested together with a measured amount of reagent or electrolyte is introduced into the cell assembly-27 and agitation is started.

Potential adjustment 70 sets two different potentials 72 and 73 to two of the active test electrode segments, e.g. electrode segments 42 and 43.
apply to

Potential 72 is set to a value that causes an electrochemical reaction of both iron and copper, while potential 73 is set to a value that causes an electrochemical reaction of only copper, which will be described in more detail later. . A reference potential is applied to the silver electrode segment 45 and a separate potential is applied to the counter electrode segment 44, thereby providing a current source to the electrolytic cell. Alternatively, counter electrode segment 44 may be grounded. 1st and 2nd
The currents or signals from the test electrode segments 42 and 43 are sent to a logic module that subtracts the first signal from the second, and a scaling factor is applied to correct if necessary. For example, the currents or signals from the two active electrode segments in bath 27 may be sent to current transducer subtractor 75 with two variable gains for adjustment. The signal is then transferred to a signal integrator 76
and then to a corrective blanking circuit 7mo, which also has a variable gain or corrector 78. The signal from the corrective blanking circuit 77 is then sent to a readout 80 and then to an auto blank adjustment 81. The signal from the blanking adjustment is returned to the corrective blanking circuit 7. If the correction is correct, the autoblank set 82 can be activated to fix the circuit. The reactions are the reduction of ferric ions to ferrous ions, the oxidation of ferrous ions to ferric ions, and the reduction of cupric ions to cuprous ions.

(Generally, no material is deposited onto the active electrode segment, so these reactions are considered to be single charge transfers rather than electrolytic or electrodeposition reactions). The reduction of ferric ions (Fe+3) to ferrous ions (Fe+2) and the reduction of cupric ions (Cu+
2) reduction to cuprous ions (Cu+1) occurs. At the active electrode segment 43 the reduction of cupric ions to cuprous ions and the oxidation of ferrous ions to ferric ions occur.
As a matter of choice, the active electrode segment 42 is set to a higher potential. The signal from one electrode is subtracted from the signal from the other electrode, resulting in: CA) F8+
3+8-→FO+2: Cu+2+o-→Cu+1 and
(2)(B) Fe
+2→Fe+3+E, Cu+2→Cu+1-e (3)
By deduction, prisoner - (B) - Fe+3 and Fe+2:C
u→0 (4) As can be seen from the above, from cupric
The reduction to copper ions is logically canceled out so that the total iron content becomes a signal that is fed into a digital or other readout.

Generally, the potential on active electrode segment 42 varies from about 0 to 1 volt, while the potential on active electrode segment 43 varies from about 0 to 1 volt.
It will vary from about 0 to 300 mV from the potential of 2.

To test serum iron according to the method described above, active electrode segment 42 would be set to a potential of about 460 mV, while active electrode segment 43 would be set to a potential of about 250 mV. It should be appreciated that the present invention is not limited to measuring serum iron only; any electroactive substance can be detected and measured using the aforementioned methods and devices. For example, the electrochemical measurement system of the present invention can be used to detect and measure heavy metals such as zinc, cadmium, lead, copper, bismuth, gold, silver and thallium in blood samples. As is well known in the art, such heavy metals usually complex with blood and therefore must be released before they can be measured. Numerous reagents for liberating such heavy metals from human blood are known in the art and are commercially available. One such reagent is METEXCH
EnvirOnmentalSci, Bethford, Massachusetts
encesAssOciates. ．． Inc. It can be obtained from. The manufacturer states that this reagent consists of a dilute aqueous solution of calcium chloride, talom trichloride, hydrogen ions, phosphate ions, acetate ions, and a dispersant. A mixture of calcium and chromium ions is said to cause the release of complexed heavy metals in the blood, and thus the total concentration of heavy metals could be measured effectively. Furthermore, the invention is not limited to the detection and measurement of heavy metals in biological samples.

For example, heavy metals complexed with gasoline can be prepared by converting a gasoline sample to ICl. NaCl. N2H4H
It can be detected and measured by dissolving it in a reagent consisting of a dilute mixture of Cl and a polyalcohol. The same reagent can be used to release various other heavy metals in various organic samples. Other reagents containing metal ions that displace the heavy metal of interest from the complex compound can also be used. Furthermore, a number of organic substances are electroactive and therefore can also be detected and measured according to the invention, including unsaturated hydrocarbons, azides, triazines and phenothiazines, amino acids. , amines and amides, phenols, aromatic OH, quinolines, quinones, imines, olefins, ketones, aldehydes, esters, and olefinic esters, ethers, organometallics, diazo compounds, nitro compounds, and halogens.

The same reagents useful for dissolving these organic materials for liquid chromatography can also be used as reagents in the method of the invention. Among the suitable reagents are: water, lower alcohols such as methanol, ethanol, isopropanol and mixtures thereof. If necessary, a strong inorganic acid such as hydrochloric or phosphoric acid, a strong base such as sodium hydroxide, or a salt such as sodium chloride may be added to the reagent to liberate the substance in question from the complex. It may be included. For example, according to the present invention, Tylenol (TylenOl)
A suitable reagent for analyzing a blood sample for the presence of morphine or heroin is about 30% methanol,
Methanol/consisting of 0.1-1% phosphoric acid and balance water
Composed of a water/phosphoric acid mixture. In order to analyze blood samples for essentially trace elements such as zinc, an aqueous calcium acetate solution buffered to PH3 has been found to be a suitable reagent. Conventional saline reagents may be used to measure glucose in blood or serum. The electrochemical measuring device of the present invention includes a biological sample,
It can also be advantageously used for the detection and measurement of substances such as cyanide, halogens, SO2, and NOx in water and sewage.

The electrochemical measurement system of the present invention can also be used to monitor electroactive substances in chemical process streams. The required electrode potential is approximately the same as that used for controlled voltage current desorption of the same organic material. The extremely high sensitivity of the electrochemical measurement system of the present invention allows accurate measurements in the picogram range. Therefore, the electrochemical measurement system of the invention can be advantageously used for soil analysis for agricultural purposes and can also be used for metal prospecting. Regarding this latter case,
The method includes measuring soil and/or water samples taken in a grid pattern to zero in on significant deposits of selected metals. For example, to zero in on deposits of relatively rare metals such as molybdenum, tungsten, vanadium, titanium, and uranium, soil or water samples taken on a grid are diluted in HCl.
Alcoholic HCl, such as a solution containing 0% methanol
Extract and analyze with reagents consisting of solutions. The electrolyte is then placed in an electrolytic cell, and one of the active electrode segments is set to a potential that oxidizes the metal in question, and the other active electrode segment is set to an electrolysis potential that oxidizes the metal in question and any other interfering metals. do. The required electrode potentials are approximately the same as those used for regulated voltage current analysis of the same metal(s). Other metals may be measured by varying the electrode potential and/or reagents. For example, for chromium the preferred reagent is 0.8NNa0
An alcoholic hydroxide solution such as a methanol solution of H. Using alcoholic HCl solution as reagent for electrochemical analysis of molybdenum, tungsten, vanadium, titanium and uranium. The use of alcoholic hydroxide solution as a reagent for electrochemical analysis of chromium is believed to be novel. Gaseous samples and/or samples contained in air can also be analyzed as follows.

j ie, the gas or air is bubbled through a suitable reagent to dissolve the substance in question. Next, the electrolytic solution is put into an electrolytic cell in the same manner as described above, and the measurement is performed in the same manner as described above. Those skilled in the art will recognize that variations may be made to this invention.

For example, the sensing electrode 34 according to the invention consists of two active test electrode segments, a reference electrode segment and a counter electrode segment, the potentials of the two active test electrode segments being dependent on the specific substance being detected and measured. Shown to be adjusted.

However, those skilled in the art will appreciate that electrode 34 may have a large number of active test electrode segments, e.g., electrode 34 may have 50 or 1 active test electrode segment.
00 electrically separated active test electrode segments, each segment electrically connected to a different potential;
It will be appreciated that it may be adapted to effectively reproduce the entire current-voltage curve. For example, the electrode 34 is
A series of potentials divided from 0 to 80 mV1
It may have two active test electrode segments. In this way, signal information from each electrode segment can be used for electrochemical analysis of samples containing various electrically active substances of interest, as well as known or suspected interfering substances. select or group only those active test electrode segments that are at specific potentials to store and produce the desired electrochemical reactions and direct signals from those electrochemical reactions to arrive at the desired measurements. It is a simple matter to sum (add and subtract) those signals. Selected active electrode segments can be connected manually, for example by an operator following printed instructions. Obviously, such a device would also include a plurality of reagents, supplies, reagent valves, etc. so that specific reagents are introduced according to the specific substance being detected and measured. Although the above device has been described as being operated under operator control, the device can also be made to operate automatically as follows: With reference to FIG. Timing control 86 and also analog timing control 8
A control tuner 85 is provided for operating 7.

Analog timing control 87 is in the ready position and is activated for analysis by start analysis control 88, visible on the instrument as test start button 24. An optical sensor 68, operated as shown in FIG.
Send a signal to 7.

If the flow through channel 65 is insufficient for complete flushing of reservoir 27, a signal from flow sensing circuit 90 causes pump 60 to stop and/or valve 63 to close. and deactivate analog timing control 87 so that analysis cannot begin without reconfiguring the instrument. A power supply 91 operated by an A/C power supply 92 sends a positive voltage through line 93 and a negative voltage through line 9.
4 and the ground potential through line 95.

The ground potential is supplied to the electric wire potential control 70. The electric potential control 70 can be controlled by a potential setting 96. In a preferred embodiment of automatic control, the device consists of two parts.

analog circuitry for conversion, conditioning and display of electrochemical signals; and reagent handling circuitry for automatic sample handling. The analysis process is controlled by two consecutive timers 87.

The first timing interval (30 seconds) is the analysis start switch 8.
It starts after 8 is pressed down. This sequence is used to bring the bath to equilibrium. The second interval (20 seconds) is the concentration measurement. During this period the electrochemical signal is converted and displayed. In a preferred embodiment, the device digitally displays a ``countdown'' or ``countup'' during the measurement.
and set by control 96. This potential is applied between the reference electrode segment 45 and the active electrode segment 42. Different potentials are seen between the active electrode segment 43 and the reference electrode segment 45. This different potential is set by the offset 2 which is operatively controlled in the current transducer subtractor 75. The equivalent potential is [0 setting 1-0 offset]. During the measurement interval, the sliding current is supplied to the current-to-voltage converter circuit 75 and is gain controlled by potentiometers "°Gain 1" and "°Gain 2".

The resulting voltage difference is picked up and provided to an integrator circuit 76 where it is integrated during the measurement interval. The integrated voltage thus has an autoblank value subtracted and obtained by the correction circuit 77. The value thus obtained is then displayed on the direct readout 80 in micrograms of iron per 100 ml of serum (μg%). When the digital display stops counting, the reagent or electrolyte containing the sample is drained into container 28 and fresh reagent or electrolyte is replenished into the tank from container 29. Test start indicator 24
When the lamp lights up again, the device can be used immediately for the next sample. The entire test takes less than 1 minute, most of which is preliminary mixing time. Reagents or electrolytes can be automatically added to the cell by a number of methods.

One method is to automatically fill the reservoir when the device changes from standby to active position, and another method is to automatically fill the reservoir at the end of each analysis step.

The pump and valve timers are set to "oZ" by control tuner 85 from the trigger signal received by the standby control switch or analytical process timer.

A solenoid valve 63 is used to control the flow of reagent to the reservoir. The pump pumps the reagent supply 62 to the nominal pressure (
e.g. 0.28 kg/Cm2 (4 psi)) and a nominal vacuum (e.g. 432 m
m(17″″) Hg). The pressure forces clean reagent into the tank 27 through the valve. This surplus in the tank is taken out to the drain storage tank 69 through the drain channel. The reagent inlet valve is left open for a short period of time, for example 8 seconds, and the pump is left on for an additional 2 seconds to drain any excess reagent above the set level from the reservoir.
A flow sensor 68, consisting of an optical sensor 56 and a flow sensing circuit 90, monitors the reservoir drain channel 65 during the reagent flushing process.

If there is no or only a small flow of reagent through the reservoir, the flow sensing circuit 90 resets the pump and valve timers 1, thereby preventing the initiation of the analysis. At this time, an alarm sound and an indicator light (light 23) may be activated. In this manner, a new process cannot be started until the operator places the meter in a standby state where the flow sensing circuit 90 is reconfigured. i The flow sensing circuit 90 has an optical sensor (LED 55 and phototransistor assembly 56, FIG. 5) and is placed in the tank outflow line. In operation, the output from the flow sensing circuit 90 changes from a low voltage level (flow path empty) to a high voltage level (reagent flowing). This level change is sensed and integrated for the first 4 seconds of the process when the reagent is in the bath. If the integrator voltage is below the preset level at the end of the 4 second interval, instrument lockout is activated. In an autoblanking operation, if a blank density reading is taken and is to be subtracted from future readings, the device is switched from "on" to ゜゜autoblank.

The auto blank set switch is depressed and a 4 second timer is started. The binary code decimal output from the display is captured in circuitry. This BCD number is then converted from digital to analog signal. An analog voltage of the correct polarity and magnitude is provided to the correction circuit and subtracted from the concentration analog voltage to produce a zero output for display.

Alternatively, the device can be operated automatically, for example by switching using a microprocessor.

In such cases, for a known substance, a tape containing instrument instructions is inserted into the microprocessor, which then selects the reagents and electrode potentials to be added to the bath. The results may then be visually displayed, such as on a CRT tube or printed, or they may be read and stored for appropriate mathematical manipulation and then displayed. For unknown substances, the instrument is instructed to connect several electrically separated active test electrodes to different potentials, thus reproducing the total current-voltage curve; The curve can then be compared to current voltage curves for known electroactive materials. Although the identity of an unknown substance can be determined using the curve shape, the amount of electrically active substance present in the sample can be determined by varying the curve shape for the unknown substance. It can be determined from the area of the part. Especially the 7th
The figure shows a typical current versus potential chart obtained in accordance with the present invention. In this graph, the horizontal axis shows the potential difference in volts of the electrode operating at increasingly positive potentials relative to the silver/silver chloride reference electrode.
The vertical axis represents the anodic current in microamperes at the indicated potential. The waves in the current versus potential curve are
It shows the sharp changes in current due to changes in concentration when each electroactive substance reacts in the reagent. Electroactive substances present in a sample are easily identified because the potential at which a particular electroactive substance reacts is characteristic of the particular substance in a particular reagent. Also, since the presence of interfering electroactive substances is offset by the transfer of electrons, the area under the peak is directly related to the total amount of each electroactive substance in the sample solution, and therefore the concentration of each substance. is connected with. A feature and advantage of the present invention is that electrochemical measurements are performed on charge transfer reactions at substantially the same time as the reactions occur.

In this way, electrochemical measurements according to the present invention can be performed by applying appropriate potentials to the various active electrode segments and classifying the signals to detect the "one or more species of interest" in the sample.
Can be done for quality at the same time. For example, a blood sample can be tested for lead and chromium simultaneously. Various other modifications will be apparent to those skilled in the art.

For example, although the active electrode segment is illustrated as consisting of a continuous ring or band, those skilled in the art will appreciate that the active electrode segment may consist of individual points or pieces or a series of points or pieces. would recognize that. Furthermore, although the electrode is preferably of a hollow cylindrical shape, the same advantages can also be achieved by making the electrode a hollow "cone" and providing a stirrer of matching size and shape. Additionally, one or more active electrode segments can be added to vary the electrode area at a selected voltage, which would otherwise interfere with the presence of very large signals from interfering electroactive materials, or in the case of very dilute solutions. The reagent signal of may be reduced or eliminated to increase sensitivity to the particular electrochemical of interest and to balance the signal.
Neither the reference electrode nor the counter electrode or the power electrode need be mounted as a segment or electrode 3"4, but can be provided separately in contact with the solution to be measured by known methods. For example. , a reference electrode and/or a counter electrode may be formed in plug 46. The device may also include one
It may have one or more reference electrodes and/or one or more counter electrodes. The apparatus may also be used to operate as a fluidized bath, thereby providing a continuous record of the process.
．． In addition to the above, as shown in Figure 8,
The electrochemical system consists of a pair of side-by-side cell assemblies -
It will be appreciated that it may consist of 27A and 27B. Bath assemblies 27A and 27B are similar to bath assembly 27 described above. In this latter case, one of the tank assemblies, for example 27A, is designed as an analysis tank, and the other tank assembly 27B is a blank correction tank. Each active electrode segment in reservoir assembly-27A is paired with a corresponding active electrode segment in reservoir assembly-27B at the same potential. In use, sample-containing reagents are injected into reservoir assembly 27A, while pure reagents are injected into reservoir assembly 27B. The vessel contents are agitated at substantially the same rate and a charge transfer signal is induced as before. Signals from the active reservoir segments in two reservoir assemblies - 27A and 27B can e.g.
is summed by subtracting from the signal induced from
As a result, all background signals are essentially eliminated.

An advantage of using two similar bath assemblies is that signals resulting from impurities in the reagents are eliminated.

Furthermore, the effects of sedation caused by changes in reagents, washing steps, etc. are also eliminated. The reservoir assemblies - 27A and 27B may consist of the same active electrode area, or one of the reservoir assemblies (typically a blank correction reservoir assembly - 27B)
may be made smaller than the analytical tank assembly 27A, and the difference in active electrode area may be electrically canceled in a known manner. As previously mentioned, the agitation speed in tank assembly-27A should be substantially the same as the agitation speed in tank assembly-27B. The simplest way to ensure that match is to mechanically couple the agitators 50A and 50B in the two tank assemblies - 27A and 27B to one motor. Alternatively, two tank assemblies may be provided, such as 27C and 27D in FIG.
As shown in FIG.
It may be stirred at 0C and 50D.

Obviously, care must be taken to prevent fluid transfer between the two reservoir assemblies - 27C and 27D. This is ensured by precise manufacturing tolerances and sealing means, as is well known to those skilled in the art. As previously mentioned, grooves 52C and 52D are provided on stirring devices 50C and 50D, respectively. If desired, these grooves may be made to move in opposite directions to minimize fluid movement between reservoirs 27C and 27D. The features and advantages of the present invention resulting from the use of an electrode with a plurality of active test electrodes at different potentials in accordance with the present invention are similar to those of the prior art electrochemical The capacitance signal that was inherent in physical measurements has been removed.

Additional features, advantages and conventions will be apparent to those skilled in the art.

[Brief explanation of the drawing]

1 is a perspective front view of a preferred embodiment of an electrochemical measuring device according to the invention, and FIG. 2 is a partially sectional front view of a preferred embodiment of an electrolytic cell of the device of FIG. 3 is an end view showing a cross section of the sample solution stirring member of the apparatus shown in FIG. 1, and FIG. 4 is a fragmentary plan view showing a cross section of a preferred embodiment of the sensing electrode element of the apparatus shown in FIG. 5 is a diagram of the flow detector elements of the device of FIG. 1, FIG. 6 is a block diagram of the electrical and pneumatic regulation and operation of the device of FIG. 1, and FIG. is a plot showing current (μA) versus potential (V) for a standard silver/silver halide reference electrode obtained in accordance with the present invention, and FIGS. 8 and 9 are plots of another embodiment in accordance with the present invention FIG. 2 is a transparent front view of an electrolytic cell.

Claims (1)

[Scope of Claims] 1. A method of electrochemically analyzing a sample to identify selected substances present in the sample, wherein the sample is dissolved in a reagent to form a test solution, and the sample is dissolved in a reagent to form a test solution. A certain amount is charged into an electrolytic cell, and a plurality of potentials are applied simultaneously from a plurality of active electrodes through the solution, a signal corresponding to a charge transfer reaction of a substance in the solution is induced from the electrode, and the selected one is A method of electrochemical analysis, characterized in that it consists of the step of classifying the signal to obtain a signal identifying the substance that has been detected. 2. In the method according to claim 1, if the sample is believed to contain a metal selected from the group consisting of molybdenum, tungsten, titanium, vanadium and uranium, the reagent consists of an alcoholic HCl solution; Also, if the sample is thought to contain chromium,
The reagent consists of an alcoholic hydroxide solution, and if the sample is blood or serum containing iron and copper, the reagent consists of a substantially equal amount of about 51/2 to 81/2 normal HCl and a lower aliphatic alcohol. An electrochemical analysis method characterized by comprising a mixture containing no iron. 3. A method according to claim 2, in which a predetermined amount of the serum or blood is introduced into the above mixture to form the test solution and a measured amount of the test solution is introduced into an electrolytic cell. adding; applying an electric potential to a first electrode of the electrolytic cell to measure the amount of copper and iron in the electrolytic cell; applying an electric potential to measure the quantity; obtaining a signal corresponding to the flow of current in each of the electrodes; and comparing the signals to measure the quantity of iron. electrochemical analysis method. 4. In the method according to claim 3, about 0
．． a potential of 4 to about 0.5 volts is applied to the first electrode, a potential of about 0.2 to about 0.3 volts is applied to the second electrode, and a signal from the second electrode is applied. is the first
An electrochemical analysis method characterized in that the signal is subtracted from a signal from an electrode. 5. The method according to claim 4, wherein the potential on the first electrode is about 460 mV and the potential on the second electrode is about 460 mV.
An electrochemical analysis method characterized in that the potential on the electrode is about 250 mV. 6. An electrochemical analysis method according to any one of claims 2 to 5, characterized in that the alcohol consists of isopropanol. 7. An electrochemical analysis method according to any one of claims 2 to 6, characterized in that the HCl concentration is about 7 formal. 8. In the method according to claim 1, about 0
An electrochemical analysis method characterized by applying a potential of ~1 volt to one of the active electrodes and applying a potential of about 0 to 300 mV to the other of the active electrodes. 9. In an electrolytic cell for electrochemical testing of samples in solution, the cell is a sensitive electrode in the form of a hollow cylindrical body defining an enclosure for holding said solution for testing; at least two active test segments, a counter electrode segment, and a reference electrode segment attached to the inner surface of the electrode, all of which have electrically active surfaces and which are electrically connected to each other by an insulating material. (a) a sensing electrode separated from the at least two active electrodes such that the electrically active surface and the inner surface of the insulating material are in the same plane as the inner surface of the body; (b) a device for connecting the reference electrode to a reference potential; and (c) a device for connecting the counter electrode to a further potential. An electrolytic cell for electrochemical testing, characterized in that the active test electrode segment is adapted to simultaneously measure at least two electrolytic currents of a sample solution with reference to a reference potential. 10 In the electrolytic cell according to claim 9,
The reference electrode is housed on the inner surface of the body 1
consisting of one or more electrode segments, each of the reference electrode segments (a) having an electrically active surface in substantially intimate contact with the interior surface of the body; and (b) An electrolytic cell for electrochemical tests, characterized in that it is electrically insulated from each other and from all other electrode segments on its body. 11. An electrolytic cell according to claim 9 or 10, the counter electrode of which comprises one or more electrode segments housed in the inner surface of said body, the counter electrode segment comprising: each (a) has an electrically active surface in substantially intimate contact with the interior surface of its body, and (b) is electrically insulated from each other and all other surfaces on its body; An electrolytic cell for electrochemical testing, characterized in that it is electrically insulated from the electrode segments of the cell. 12. The electrolytic cell according to any one of claims 9 to 11, wherein the reference electrode is made of silver,
An electrolytic cell for electrochemical testing, characterized in that the active test electrode and the counter electrode thereof are made of carbon. 13. In an electrolytic cell for the electrochemical testing of samples in solution, the cell having a sensing electrode in the form of a hollow cylindrical body defining an enclosure for holding said solution for testing; at least two attached to the inner surface of
an active test segment, a counter electrode segment, and a reference electrode segment, all of which have an electrically active surface;
sensing electrodes electrically separated from each other by an insulating material, such that the electrically active surface and the inner surface of the insulating material are in the same plane as the inner surface of the body; and (a) a device for connecting the at least two active test electrode segments to different potentials, (b) a device for connecting the reference electrode to a reference potential, and (c) a device for connecting the counter electrode to a further potential. an apparatus, wherein the active test electrode segment is at least 2 volts of sample solution with reference to a reference potential.
The first one is designed to be able to measure two electrolytic currents simultaneously.
and a second electrolytic cell, the first electrolytic cell being adapted to hold a sample in a reagent and to measure a charge transfer reaction between the sample and the reagent; the second electrolytic cell is adapted to hold only the reagent and measure the charge transfer reaction of the reagent alone, and the first and second electrolytic cells have corresponding active electrode segments; , wherein the corresponding segment in the first electrolytic cell is paired at the same potential as the corresponding segment in the second electrolytic cell. 14. An apparatus for electrochemically testing a sample in solution for the identification of selected substances therein, the apparatus comprising at least one electrolytic cell as defined by claim 13. and an apparatus for comparing signals corresponding to currents in at least two active test segments in order to determine by comparison the amount of a selected substance in the sample. Test equipment. 15. In an electrolytic cell for electrochemical testing of samples in solution, the cell having a sensing electrode in the form of a hollow cylindrical body defining an enclosure for holding said solution for testing, said body at least two attached to the inner surface of
one active test segment, a counter electrode segment and a reference electrode segment, all of which have electrically active surfaces and are electrically separated from each other by an insulating material; a sensing electrode, the electrically active surface and the inner surface of the insulating material being in the same plane as the inner surface of the body; and (a) connecting the at least two active test electrode segments to different potentials. (b) a device for connecting the reference electrode to a reference potential; and (c) a device for connecting the counter electrode to a further potential, wherein the active test electrode segment is connected to a reference potential. An electrolytic cell consisting of a first electrolytic cell and a second electrolytic cell capable of simultaneously measuring at least two electrolytic potentials of a sample solution, the first electrolytic cell containing a sample in a reagent. and the second electrolytic cell is adapted to hold only the reagent and to measure the charge transfer reaction of the reagent alone. and the first and second electrolytic cells have corresponding active electrode segments, and the corresponding segment in the first electrolytic cell is the same as the corresponding segment in the second electrolytic cell. at least one electrolytic cell paired in potential and a device for comparing signals corresponding to the currents in at least two active test segments in order to determine by comparison the amount of a selected substance in the sample; further comprising (d) a stirring device housed in the sensing electrode; (e) a sample preparation device for introducing a measured amount of sample into the sensing electrode; (f) inside the sensing electrode. a charging device for introducing electrolyte into;
An electrochemical test device characterized by comprising: (g) a take-out device for taking out the electrolyte from the sensing electrode; (h) a device for supplying the electrolyte to the above-mentioned charging device; 16. In an electrolytic cell for the electrochemical test of serum iron, the cell has a sensing electrode in the form of a hollow cylindrical body defining an enclosure for holding said solution for the test, attached to the inner surface of said body. at least two active test segments, a counter electrode segment and a reference electrode segment, all having electrically active surfaces and electrically separated from each other by an insulating material. a sensing electrode, wherein the electrically active surface and the inner surface of the insulating material are coplanar with the inner surface of the body; and (a) the at least two active test electrode segments. (b) a device for connecting the reference electrode to a reference potential;
and (c) a device for connecting the counter electrode to a further potential, wherein the active test electrode segment is configured to simultaneously measure at least two electrolytic potentials of the sample solution with reference to a reference potential. an electrolytic cell consisting of a first and a second electrolytic cell, the first electrolytic cell holding a sample in a reagent, and measuring a charge transfer reaction between the sample and the reagent; the second electrolytic cell is adapted to hold only the reagent and measure the charge transfer reaction of the reagent alone, and the first and second electrolytic cells are and, by comparison, at least one electrolytic cell having an active electrode segment with an active electrode segment in which the corresponding segment in the first electrolytic cell is paired at the same potential as the corresponding segment in the second electrolytic cell; consisting of a device for comparing signals corresponding to currents in at least two active test segments to determine the amount of a selected substance in the sample, one of the electrode segments being active for both iron and copper; one electrode segment adapted to measure a second charge transfer for a separate quantity selected from iron and copper; an apparatus for applying a first potential for measuring charge transfer of both iron and copper;
an apparatus for applying a second potential for measuring the charge transfer of separate amounts selected from iron and copper to the other electrode segment; and by comparison determining the amount of iron in the sample; An electrochemical test device comprising: a device for comparing signals corresponding to first and second charge transfers for measurement. 17. In an electrolytic cell for electrochemical testing of samples in solution, the sensing electrode in the form of a hollow cylindrical body defining an enclosure for holding said solution for testing, said body at least two attached to the inner surface of
an active test segment, a counter electrode segment, and a reference electrode segment, all of which have an electrically active surface;
sensing electrodes electrically separated from each other by an insulating material, such that the electrically active surface and the inner surface of the insulating material are in the same plane as the inner surface of the body; and (a) a device for connecting the at least two active test electrode segments to different potentials, (b) a device for connecting the reference electrode to a reference potential, and (c) a device for connecting the counter electrode to a further potential. an apparatus, wherein the active test electrode segment is at least 2 volts of sample solution with reference to a reference potential.
The first one is designed to be able to measure two electrolytic potentials simultaneously.
and a second electrolytic cell, the first electrolytic cell being adapted to hold a sample in a reagent and to measure a charge transfer reaction between the sample and the reagent. the second electrolytic cell is adapted to hold only the reagent and measure the charge transfer reaction of the reagent alone, and the first and second electrolytic cells have corresponding active electrode segments. at least one electrolytic cell in which the corresponding segment in the first electrolytic cell is paired at the same potential as the corresponding segment in the second electrolytic cell and, by comparison, the selected cell in the sample. (d) a stirring device housed in said sensing electrode; (e) A sample loading device for introducing a measured amount of sample into the sensing electrode; (
F) A charging device for introducing the electrolyte into the sensing electrode; (G) A take-out device for taking out the electrolyte from the sensing electrode; (H) A device for supplying the electrolyte to the charging device; (i) includes a device for flushing electrolyte through the electrolytic cell to remove the electrolyte from the cell and replace it with fresh electrolyte, the washing device supplying fresh electrolyte to the electrolytic cell; a first conduit for
a second conduit for receiving waste electrolyte from the electrolytic cell, an optical emitter and an optical detector on opposite sides of one of the first and second conduits, and between the emitter and the detector; comprising a curved transparent wall within one of the conduits, whereby radiation from the radiator is more completely focused onto the detector while the electrolyte is in the conduit; An electrochemical test device featuring: