Abstract: A process for the electrochemical regeneration of a co-enzyme, which process comprises the steps of(i) electrochemically oxidizing a medium containing oxidized co-enzyme and biochemically inactive isomers of the co-enzyme to oxidize the biochemically inactive isomers,(ii) generating a mercury amalgam in an electrochemical cell;(iii) contacting in a reaction vessel the mercury amalgam and the medium containing the oxidize co-enzyme from step (i), with one of the reactants selected from the mercury amalgam and the oxidized co-enzyme being in the form of a plurality of droplets.

Abstract: An electrode refreshing arrangement of a biosensor includes a constant reverse bias voltage arranged to be supplied between a working electrode and a reference electrode, so as to thereby refresh the working electrode, that is, to remove the disturbance film or substance formed on the surface of the working electrode as a result of the enzyme reaction, thus reviving the activity of the working electrode.

Abstract: A variation of Pulsed Coulometric Detection (PCD) is described in which the detection potential is scanned in a cyclic fashion during current integration to achieve automatic and virtual elimination of baseline drift caused by surface roughening and changes in pH. The technique is examined at a Au electrode for flow-injection determination if thiourea which is typical of numerous sulfur compounds whose anodic reactions are catalyzed by formation of surface oxide. The baseline decays quickly to a near-zero equilibrium value following start-up and is unchanged for a pH step of ca. 2 units. The technique is concluded to be compatible with pH-gradient chromatography.

Abstract: A modular multi-channel automated medical analyzer device is disclosed, characterized by use of an ion selective electrode and/or enzymatic electrode/wash cell system which permits rapid analysis of various substances of interest contained within undiluted body fluids such as whole blood, serum and/or plasma. The ion selective electrode and/or the enzymatic electrode are disposed upon a probe which automatically axially reciprocates downwardly in a simple manipulative motion between an open-ended reference wash cell and a sample cup bearing the body fluid specimen to be analyzed. The wash cell includes an inlet port and one or more outlet ports through which is circulated an aqueous solution bearing a known concentration of the substance to be measured to provide a reference calibration medium as well as a probe washing medium.

Abstract: An analytical method using a sensor of the enzyme electrode type is provided for determining in a sample the concentration of an analyte reactive with an enzyme present on the sensor to produce an electrochemically active species detectable by the sensor, which comprises applying a potential across the sensor to cause an electrical current to flow therethrough, contacting the sensor with the sample thereby causing a change in the current flow and, when a working potential is applied across the sensor, determining the concentration of the analyte as a function of the change in the current characterized in that at some time before the working potential is applied and the concentration of the analyte is determined a potential significantly in excess of the working potential is applied, whereby to reduce the period required to establish a signal sufficiently stable to permit the determination to be effected.

Abstract: A diffusion-limiting membrane holding means for a sensor comprising: a slender resilient thin plate, of which one shorter side serves as an engagement side, and of which one longer side is provided at its predetermined position with an engagement portion, an opening being formed in the thin plate between the engagement side and the engagement portion; and a diffusion-limiting membrane integrally attached to the thin plate as covering the opening; whereby the resliency of the thin plate causes the diffusion-limiting membrane to be stuck to the surface of an enzyme electrode unit of a sensor, thus enhancing the accuracy of concentration measurement of a target substance to be measured.

Abstract: A method for determining the effective quantity of an organic additive in an electroplating bath involving passing an inert electrode through a predetermined sequence of voltammetric steps including a step of plating the electrode at a given applied potential, stripping the plated metal at a given applied potential, and conditioning the inert electrode without applied potential; correlating the quantity of additive with the coulombs utilized during the metal stripping step; and using the same predetermined sequence of voltammetric steps for a bath having an unknown quantity of additive.

Abstract: A method for determining the effective quantity of an organic additive in an electroplating bath involving passing an inert electrode through a predetermined sequence of voltammetric steps including a step of plating the electrode at a given applied potential, stripping the plated metal at a given applied potential, and conditioning the inert electrode without applied potential; correlating the quantity of additive with the coulombs utilized during the metal stripping step; and using the same predetermined sequence of voltammetric steps for a bath having an unknown quantity of additive.

Abstract: The invention relates to a method for measuring and adjusting electrochemical potential and/or component content in the process of treating valuable materials, when the valuable materials should be recovered either together or separately by aid of the values of the recovery range defined on the basis of electrochemical potential and component control. According to the invention, the measuring of electrochemical potential and/or component content is carried out by means of at least one electrode (4, 5), advantageously by means of a mineral electrode, so that in order to regulate the physicochemical state of the electrode and/or to remove the coating layer formed on the electrode surface and in order to protect the electrode, onto the electrode there is switched a supply voltage differing from the electrochemical balance potential of the electrode, which supply voltage is switched off before starting the measuring operation.

Abstract: A glucose sensing apparatus and method includes an electrocatalytic sensor having a reference electrode and a sensing electrode. A periodic signal is comprised of a ramp voltage which is intermingled a series of square wave measurement pulses. This signal is applied to the sensor. Current levels are sampled twice during each measurement pulse, and a signal indicative of glucose level is derived therefrom. After completion of a measurement, a reactivation, signal is applied to the electrode to regenerate deteriorated surfaces thereof.

Abstract: A method of determining one gas in the presence of another, where the one gas is reactive with an electrochemical product of the other, comprisesapplying the gases to one side of a membrane permeable to the two gases, the other side of the membrane retaining a solvent for both gases and for the electrochemical product,applying, for the predetermined duration through a working electrode in contact with the solvent, a potential which electrolyses (e.g. reduces) the (dissolved) other gas to form the said electrochemical product,applying, through the working electrode, a potential for reconverting the product to the dissolved gas,measuring, at a predetermined instant or integrated over a predetermined time slot, the current flowing at the reconversion potential, and,from the amount by which the measured current (or integrated current, i.e. charge) falls short of the current when the said one gas is absent, determining the concentration of the said one gas.

Abstract: The electrochemical determination of the oxygen concentration, particularly in biological matter, is possible by means of an oxygen sensor with a measuring electrode and a counter electrode over long periods of time, even if the sensor is implanted, by taking the following measures; two potentials are cyclically impressed on the measuring electrode, with one potential (measuring potential) in the range -1.4 V.ltoreq..rho.Ag/AgCl.ltoreq.-0.4 V, and the other potential (recovery potential) in the range -0.2 V.ltoreq..rho.Ag/AgCl.ltoreq.+0.2 V; the dwelling time at the measuring potential is small as compared to the duration of the cycle; and the current flowing during the measuring period is evaluated as the measuring signal.

Abstract: An improved electrolytic cell, the electrodes of which can be readily cleaned, and resensitized by the application of fresh electrolyte upon the electrodes. The cell includes a cleaning assembly integral with the cell body, and the electrodes of the cell are integrated with a plunger reciprocably mounted within the cell body. In operating position, the electrodes are extended by actuation of the plunger into a thimble insert which, with the components provided by the thimble insert provide the essential components of an operative cell. The plunger, when the cell has become insensitive due to desensitization of the electrolyte, can be withdrawn from the thimble insert, aligned with the cleaning apparatus, the electrodes cleaned and a fresh electrolyte installed upon the electrodes, and the electrodes returned to operative position by mere reactuation of the plunger.

Abstract: The effectiveness of organic additives acting as inhibitors during the electrolytic deposition of metals from aqueous electrolytes, which contain organic additives for improving the deposition of metal, is electrically measured. In order to permit an improved and more reliable check of the effectiveness of the inhibitor and to permit a controlled supply of makeup inhibitors at the required rate, a partial stream of the electrolyte is supplied to flow at a constant velocity in a measuring cell provided with at least three wire electrodes having a fresh conductor surface, a measuring current of 5 mA to 1.0 A is supplied to the electrodes and is maintained, and the slope of the plotted cathode potential-time curve in the range from 0.1 to 50 minutes is taken as a measure of the effective conecentration of the inhibitor.

Abstract: A method of regenerating a membrane-enclosed amperometric or Clark cell having an operative current range for electroanalytical operation limited by a maximum current density of typically not more than 100 .mu.A/cm.sup.2 at the working electrode by subjecting at least one of the probe electrode in contact with a regeneration electrolyte, while the membrane is removed, to a regeneration current for causing a current density in the range of from about 1 to about 1000 mA/cm.sup.2 which is substantially higher, e.g. by a factor of at least 10 and preferably at least 100, than the maximum current density in electroanalytical operation.

Abstract: A residual analyzer assembly including an analyzer probe, typically of the amperometric type having a stable zero calibration, and a working fluid sampler system having means for backflushing the flow so as to periodically cleanse the system. The residual analyzer probe having two bare electrodes operating as a working electrode and a counter electrode. The working electrode being formed in a double spiral helix with the counter electrode being formed in an outer peripheral ring closely adjacent the working electrode. The probe also including a third electrode within an electrolytic solution and positioned behind a membrane located directly behind the working electrode. The three electrode system operated utilizing a potentiostat type circuit. The working fluid sampler system adapted to sample a portion of the working fluid flow and maintain a constant pressure into a flow block. A controlled amount of reagent being added for proper residual analyzation of the sample.

Abstract: An apparatus for etching supports that have deposited thereon an etchable metal with an etching medium, which apparatus includes an etching chamber, means to convey the supports with metal deposited thereon through the etching chamber, a plurality of nozzles which are positioned to spray etching medium containing acid on the supports as they move through the etching chamber, a sump for receiving residual etching medium withdrawn from the etching chamber, a first circulating system for circulating residual etching medium from the sump back to the plurality of nozzles, a reservoir for an oxidizing agent, a device for regulating the addition of oxidizing agent into the circulating system in an amount which is stoichiometrically in excess of that required to remove metal from the supports, a chamber containing a metal which will react with the oxidizing agent, a second circulating system for circulating residual etching medium from the sump through the chamber containing a metal, a regenerating chamber to receive

Abstract: A stripping analysis method comprises a preelectrolysis step during which liquid to be analyzed is introduced into a measurement cell at a pulsating rate, a working electrode is vibrated at an ultrasonic frequency, and the voltage potential between the working electrode and a reference electrode is adjusted to a level which allows the substances to be determined to be deposited on the working electrode. After the preelectrolysis step is a stripping step during which the voltage potential between the working electrode and the reference electrode is scanned through the potential range where the substances to be determined are dissolved back to the liquid and current is measured while the liquid in the measurement cell remains essentially undisturbed. The method also comprises an elimination step during which the voltage potential between the working electrode and the reference electrode is adjusted to a level at which the working electrode is regenerated.

Abstract: An antifouling electrochemical gas sensor is disclosed in which the sensor has a cell containing two spaced apart electrodes immersed in an electrolyte and a membrane over an opening in the end of the cell which is immersed in a medium containing varying concentrations of a gas to be sensed, typically oxygen. The electrodes are also connected to an external electrical circuit which indicates the current flow between the electrodes as a result of oxidation and reduction reactions at the electrodes caused by oxygen diffusing through the membrane into the cell. The sensor has a sensing mode during which it functions to indicate the amount of oxygen in the medium. The sensor also has a cleaning mode in which the current flow across the electrodes is in an opposite direction to cause a reaction at one of the electrodes producing a biocidal gas.

Abstract: A method is disclosed for conditioning a gas sensor. The electrode arrangement of the sensor is surrounded by an electrolyte and is partitioned off from the atmosphere by a gas-permeable membrane. The electrode arrangement is introduced into a calibrating gas and the calibrating gas is kept in isotonic equilibrium with the electrolyte. The composition of the electrolyte is not varied substantially while maintaining the operating conditions of the sensor and without having to introduce the sensor into a medium containing the calibrating gas. For this purpose, the membrane of the sensor is covered with a gas-tight and water-vapor-tight overlay, and the isotonic equilibrium is brought about and maintained by means of the gas that diffuses out of the electrolyte through the membrane as far as the overlay.

Abstract: The method of operating a two electrode electrochemical detector cell in which the cell is connected to an external current measurement circuit through a cyclically operated switch which alternately opens and closes the connection between the cell and the external circuit. The cell is operated without bias potential. The peak current obtained from the cell after closing the connection to the external circuit may be measured immediately without any delay for transient current to decay. Means are disclosed for automatically compensating for background current error in the cell current measurement.

Abstract: An electrochemical sensor capable of determining the partial pressure of various gases (e.g., CO, CO.sub.2, H.sub.2 S, alcohol vapors, hydrocarbons, NO.sub.x, etc.) and, optionally, substantially concurrently, but independently, oxygen content in gases and liquids. The sensor measures the amount of chemisorbent species formed either electrochemically by partial reduction (such as "Reduced-CO.sub.2 " in the case of CO.sub.2) or partial oxidation (in the case of alcohol) or non-electrochemically via specific adsorption (in the case of CO and hydrocarbons) on platinum or other metals. The charge required to oxidize this chemisorbed species is proportional to the amount of adsorbate on the electrode surface which is made a reproducible and reliable function of the partial pressure of the gas to be measured. By the proper selection of the sensor construction and electrical parameters, high sensitivity, fast response time, and high selectivity can be obtained.

Abstract: The present invention is for an electrochemical cell and method for quantitatively detecting noxious gas which comprises a first working electrode comprising a gas diffusion membrane having bonded thereto a catalytic portion electrochemically reactive with the noxious gas; a second working electrode having electrochemical activity with the oxidation/reduction products produced at the first working electrode; a counter electrode; a reference electrode; an electrolyte; means for containing said electrolyte and said electrodes; means for maintaining a fixed potential on said first working electrode relative to said reference electrode of from about 1.0 to 1.8 volts with respect to the potential of the reversible hydrogen couple of the electrolyte of the cell; and means for maintaining a fixed potential on said second working electrode relative to said reference electrode of from about 1.0 to 2.

Abstract: An improved method and apparatus for deplating the electrodes of cutaneous oxygen sensors. A controllable voltage source selectably establishes either a polarizing voltage or a deplating voltage between the electrodes of a cutaneous oxygen sensor, while a current sensing circuit measures the current flow therebetween. If, during the calibration of the sensor, the current flow exceeds a predetermined threshold, the apparatus initiates an operator assisted sequence of operations which deplate the electrodes and restore the gas sensor to a usable operating condition. During the performance of this sequence of operations, the apparatus carries out all steps, except those which must be performed manually by an operator.

Abstract: The measuring device (10) comprises an ISFET (12) used as a chemically selective ion sensor, a reference electrode (20) positioned adjacent the ISFET (12), an amplifier (22) coupled to the ISFET and control/correction circuitry (30) coupled to the ISFET (12), to the reference electrode (20) and to the amplifier (22). The control/correction circuitry (30) is operable to maintain the drain-source current I.sub.DS of the ISFET (12) at a constant value and to correct drift effects of the ISFET (12) on the basis of the logarithmic equation:.DELTA.V.sub.p =A 1n(t/t.sub.o +1 )where:.DELTA.V.sub.p =potential driftA=scale factor for drift and amplitudet.sub.o =time constant defining the dependence on timet=time during which the sensor is operative in the event of continuous operation.

Abstract: An automatically depolarizing electrode system for analyzing ions and gases in a solution, especially in blood. A magnetic stirrer is placed in a test chamber of the electrode system and rubs the sensing surface of the electrode which constitutes the wall of the test chamber. During analysis, the rotating stirrer prevents blood from coagulating on the sensing portion of the electrode, so that the electrode is constantly kept clean and depolarized. Preferred is a flat and solid state ion selective electrode for this electrode system. Additionally, the size of the stirrer is designed not only to lessen the amount of a sample solution which is present in the test chamber but to prevent the reading response from retarding.

Abstract: A flow path in a flow analyzing apparatus is branched into two or more branch flow paths. In one of the branch flow paths, a flow path blockage detector and an electrolyte measuring electrode are disposed, and in the other branch flow path, a gas measuring electrode is disposed. When a liquid sample is introduced into the flow paths from a sampling nozzle of the common flow path, the blockage detector detects whether a blockage is occuring. If the blockage is detected, the blockage is removed by feeding a cleaning fluid into the common flow path in a direction opposite to the flow of the sample. Following this, the sample is introduced into the other branch flow path. By this operation, the pressure in the other branch flow path is not reduced abnormally, and thus normal operation of the gas measuring electrode can be maintained.

Abstract: A method is disclosed for conditioning a gas sensor. The electrode arrangement of the sensor is surrounded by an electrolyte and is partitioned off from the atmosphere by a gas-permeable membrane. The electrode arrangement is introduced into a calibrating gas and the calibrating gas is kept in isotonic equilibrium with the electrolyte. The composition of the electrolyte is not varied substantially while maintaining the operating conditions of the sensor and without having to introduce the sensor into a medium containing the calibrating gas. For this purpose, the membrane of the sensor is covered with a gas-tight and water-vapor-tight overlay, and the isotonic equilibrium is brought about and maintained by means of the gas that diffuses out of the electrolyte through the membrane as far as the overlay.

Abstract: Analysis of a series of samples is carried in an electrode cell (10) containing an ion-selective electrode (11). A base solution, to which a trace of the ion to be measured has previously been added, is run into the cell (10). To perform an analysis a small volume of solution, containing a known concentration of the ion is added, followed by an identical volume of sample. The pX or mV measurement before and after each of the two additions is recorded and the analytical result calculated. After analyzing the first sample, the cell is drained, without rinsing and the second sample analyzed in the same way. No blank determination is required. In more sophisticated versions of the technique, at least two additions of standard are made, one before and one after the sample.

Abstract: An improved electrochemical cell is described which comprises at least one electrode having increased signal strength achieved by treating at least the working surface of the electrode with a coating of a polytetrafluoroethylene and a catalyst metal selected from the group consisting of platinum and the oxides thereof in an aqueous oligosaccharide solution. Following coating, the electrode is heated to a temperature below the sintering temperature of the polymer to thermally convert the oligosaccharide in the presence of the catalyst metal and drive off the conversion products. An electrode thus treated exhibits a substantially inproved signal strength as compared to an electrode of the same construction which has not been treated in accordance with the invention.

Abstract: An improved oxygen sensor is provided which gives oxygen concentration readings immediately and without the uncertain delays of a break-in period. The break-in period is decreased substantially by imparting to a copper counter electrode a uniform distribution of cuprous oxide throughout its structure. More reliable performance of the sensor is achieved.

Abstract: A testing module is provided having units which can be arranged seriatim to provide narrow through passageways linked to each other for quantitative determination of analytes passing through the units as by electrical testing with electrodes. Auxiliary passageways are preferably used in one unit to allow flushing of a first sample chamber without contamination from a second sample chamber. An electrode holder carries a membrane backed by a gel to aid in electrically linking the membrane to an electrode and to support the membrane in a substantially planar condition in use.

Abstract: A halogen ion concentration in a solution is measured by bringing halogen ion-selective detection means comprising a silver/silver halide electrode, and a reference electrode into a solution whose halogen ion concentration is to be measured, and measuring an electromotive force of the halogen ion-selective detection means in the presence of silver ions dissolved in the solution. The electromotive force corresponds to the halogen ion concentration in the solution.

Abstract: An improved system for the monitoring of pH of a liquid containing oil and water by directing the flow of at least a portion of the liquid into contact with the electrode of a pH meter for measuring the pH of the liquid, interrupting the flow of liquid to the electrode periodically, directing the flow of a washing solution into contact with the electrode to remove any depositions on the electrode, and then resuming the flow of the liquid into contact with the electrode to continue the monitoring of pH of the liquid without the need for manual removal and cleaning of the glass electrode.

Abstract: The clogging of junctions of electrochemical reference cells by contaminants is prevented by a triple junction design incorporating dual, independently operative flushing conduits. The first conduit flushes the exterior of the first junction and the exterior of the second junction, and the second conduit flushes the interior of the second junction and the exterior of the third junction. When the cell is used in-line on a chemical process stream, pressure equalizing means are employed between the stream and the standard electrode, of which the third junction is an element. Elevation of the exits of the flushing conduits above the junctions releases air from the cell which may collect at the junctions and impair the accuracy of the readings.

Abstract: In an apparatus for determining the oxygen content of a liquid by measuring the electric current between two electrodes (20, 21) of different materials which are immersed into the liquid, each electrode (20, 21) is embedded in its own body (18, 19) of insulating material in such a manner that only one end surface (20a, 21a) of each electrode is free and may be electrochemically active. The respective structural units (13, 14) consisting of an electrode and insulating body are pressed via associated springs (30, 31) at a common grinding device (28) displaceable by a driving apparatus, which grinding device serves for cleaning the free electrode end surfaces (20, 21a). The spring force by means of which the pressing to the grinding device (28) occurs is individually adjustable for each of the structural units (13, 14) by adjustment of a support ring (32,35) for the relevant spring (30, 31) to match the hardness, abrasion-resistance and corrosion properties of the material of the revelant electrode.

Abstract: An improved electrochemical cell and detector which is especially suited for analysis of rapidly changing flowing streams such as found in high performance liquid chromatography is disclosed. A uniquely designed jet made of microbore drawn capillary tubing permits the construction of a cell for very low flow rates that still retains true wall-jet hydrodynamics. The invention prevents changes in cell response in time by periodically cleaning a working electrode in a novel way. Cleaning and detection are both accomplished on a time scale much shorter than the fastest liquid chromatograph peaks by means of a unique three electrode cell design utilizing a small diameter, low capacitance, metal working electrode situated close to a reference electrode.

Abstract: The calibration of a polarographic oxygen sensor (20) at zero oxygen concentration is accomplished by providing an oxygen-free liquid environment at the sensor active surface. This is accomplished electrolytically by depleting a thin film of electrolyte (24) of oxygen to zero concentration with an oxygen-reducing cathode (6), and complementary anode (4), connected via a battery (10) and switch (12). The sensor (20) is placed into close proximity with the electrodes (4,6) and the oxygen in the electrolyte (24) reduced while its concentration is measured by the sensor (20). A low steady-state signal for the sensor provides the zero oxygen concentration calibration point.

Abstract: To permit calibrating and testing a current-limiting sensor in situ, the sensor is exposed, from time to time, to ambient air forming a standard gas, and the output thereof compared with a standard, for example by connecting a resistor (4) of standard value in circuit therewith or for recalling from a memory (23) in a microcomputer (22) standard conditions; upon determination of a deviation between output from the sensor (2) when exposed to the standard gas--typically air--and the theoretical value as stored, the theoretical or reference value is reset if the deviation is within a predetermined limit or, otherwise, an alarm output is provided. The tolerance limits can be set in such a way that a first alarm output is provided in a narrow tolerance, thus indicating drift of the sensor toward eventual malfunction, and permitting utilization of the sensor for long lifetime, while providing advance warning of imminent failure.

Abstract: The invention is concerned with an electrochemical gas analyzer for determining the sulphur dioxide content of certain gases in particular, flue gases. The device comprises a measuring cell containing a measuring electrode for the determination of the depolarization current and further comprising an unpolarizable electrode in the same electrolyte. The gas input flow is utilized to cause a circulation of electrolyte containing the dissolved gas which moves in the space between the measuring and counter-electrode. The electrolyte is continuously renewed and the electrolyte leaving the cell is regeneratd and recycled. The sulphur dioxide dissolved in the electrolyte is removed outside the cell by treatment with air in the presence of activated charcoal.

Abstract: The disclosed apparatus quickly measures ionic concentration of an electrolyte with an ion sensitive electrode means, by using a number of measuring cups disposed along a circle on a turntable and a series of treating stages fixed along but outside the turntable so as to face different measuring cups as the turntable stops at different angular positions, whereby various treatments necessary for the ionic concentration measurement are carried out simultaneously in parallel at different measuring cups, so as to shorten the measuring time of the ionic concentration.

Abstract: For determining the urea concentration in liquids in continuous operation, with high sensitivity and reliable determination of the urea content over an extended period of time, an electrode which is separated from the urea containing liquid by means of a diaphragm with a diffusion coefficient of less than 10.sup.-7 cm.sup.2 s.sup.-1 for urea has impressed on it potentiostatically and cyclically, two potential values, the more positive potential being between 0.9 and 2.0. V/H.sub.2 rev and the more negative potential being lower than 0.6 V/H.sub.2 rev, and at the more positive potential, the current flowing within a predetermined time interval is evaluated as the measuring signal.

Abstract: An improved sensing electrode assembly for testing for a constituent in blood is provided. An electrode assembly exhibits a decreased time to reach stable operation by virtue of having the assembly pretreated by applying thereto a liquid containing blood derived albumin.

Abstract: An improved electrochemical cell and detector which is especially suited for analysis of rapidly changing flowing streams such as found in high performance liquid chromatography is disclosed. A uniquely designed jet made of microbore drawn capillary tubing permits the construction of a cell for very low flow rates that still retains true wall-jet hydrodynamics. The invention prevents changes in cell response in time by periodically cleaning a working electrode in a novel way. Cleaning and detection are both accomplished on a time scale much shorter than the fastest liquid chromatograph peaks by means of a unique three electrode cell design utilizing a small diameter, low capacitance, metal working electrode situated close to a reference electrode.

Abstract: A method for determining the concentration of sugar in the presence of interfering foreign substances, by means of a test electrode with a membrane placed in front of it, the electrode being contained in an electrocatalytic sugar sensor, whereby the test electrode is set potentiostatically to a reactivation potential and to a test potential and the current flowing during the set test period is evaluated as a test signal. The invention formulates a method such that with varying concentrations of urea a sensitive determination of sugar concentration which is reliable over a long term is achieved. The invention discloses the method which includes the step that after the reactivation potential and prior to the test potential a third potential that is more negative than the test potential is applied to the test electrode. The technique proposed in the invention is particularly appropriate for the determination of the concentration of glucose in body fluids.

Abstract: An electrode system for measuring oxygen gas in a solution comprises a pair of electrodes consisting of an indicator electrode and a reference electrode immersed in an electrolyte solution and a membrane pressed against the indicator electrode. On the other side of the membrane, is a solution to be analyzed. In determination of gas in solution especially in blood, good reproducibility of data, a stable reading and a long performance life are obtained by rubbing the surface of the indicator electrode and rotating a magnetic stirrer on the membrane. These effective measures prevent the electrode and the membrane from being contaminated. Accordingly, continuous analysis of arterial blood can be achieved.

Abstract: An apparatus and method are disclosed for the continuous monitoring of pH in a fluid stream flowing at a low volumetric flow rate. The stream is directed through an enclosed conduit with a glass electrode sealed therein. The conduit wall facing the electrode has contour approximately complementary in shape to the sensing surface of the electrode with a narrow gap between the opposing surfaces through which the fluid passes, forcing rapid and uniform flow of the fluid over the electrode surface. Continuous operation is thereby permitted for extended time periods without substantial fouling of the surfaces.

Abstract: A pH sensor comprising a sleeve assembly having at least first and second spaces, a partition separating the two spaces from each other with a water tight seal, and a barrel including a flange, a reference electrode accommodated in the first space and including a liquid junction, a glass electrode having a sensor unit disposed adjacent to the liquid junction, liquid grounding means mounted adjacent to the liquid junction, and a cable disposed in the second space with a watertight seal, the cable being electrically connected to the reference electrode, glass electrode and liquid grounding means. The pH sensor can be used for continuous flow, immersion or submersion types of installations, and can be fabricated inexpensively and is easily maintained. The sensor unit of the pH sensor can be easily cleaned by a cleaning unit which includes a rotatable shaft to which is connected a vane and a brush at one end.

Abstract: A probe immersible in process water or wastewater having oxygen, chlorine or another gas dissolved therein and adapted to continuously and accurately measure the concentration of the gas. The probe includes a noble metal measuring electrode, an oxidizable metal counter-electrode and an electrolyte which in combination with the electrodes defines an electro-chemical cell whose output current depends on the amount of the gas passing into the cell through a diffusion membrane permeable to the gas being analyzed. In order to simulate the effect of rapid sample flow past the membrane and thereby maintain the analytical sensitivity of the instrument, the probe is vertically supported through a flexible coupling and includes an internal motor having an unbalanced rotor secured to its shaft. Rotation of the rotor causes the probe to nutate about its vertical axis to simulate the effect of a rapid sample flow.

Abstract: Disclosed is a method for regenerating an ion-selective electrode equipped with an ion-selective membrane which is formed of a polymer membrane containing an ion-selective material and plasticizer, which method comprises supplying to the ion-selective membrane a regenerating plasticizer which is either identical in every aspects or analogous in effects to the first-mentioned plasticizer and is capable of dissolving the ion-selective material therein and imparting flexibility to the ion-selective membrane. Also disclosed are several embodiments of ion-selective electrodes and ion-concentration analyzers containing means for practicing said method.