Abstract: A limiting-current-type hydrocarbon sensor of the present invention comprises a solid electrolyte formed of a barium-cerium-based oxide, capable of detecting hydrocarbon stably and accurately regardless of whether no oxygen is present or a high concentration of oxygen is present. The cathode on the surface of the solid electrolyte is formed of an alloyed layer including Au and Al. In particular, an alloyed layer including an Al—Au intermediate phase is suited for the alloyed layer of the cathode. The alloyed layer comprises a first layer including an Al—Au intermediate phase that is in contact with the surface of the solid electrolyte, and a second layer including a metal Al phase that covers the first layer. The Al phase of the alloyed layer blocks oxygen, and the Al—Au intermediate phase smoothens hydrogen association and reduces the resistance of the electrode. The hydrocarbon sensor can thus detect hydrocarbon accurately even when oxygen is included in an atmosphere.

Abstract: A modular, in particular multidimensional system for the reagent-free, continuous detection of a substance is disclosed. The system is characterized by the presence of at least two measurements modules of preferably different types. The modules are robust and designed for a long-time operation. They have an exchangeable or replaceable selective layer structure. The system may also include appropriate modules for amperometry and optical sensors.

Abstract: A small volume sensor, and methods of making, for determining the concentration of an analyte, such as glucose or lactate, in a biological fluid, such as blood or serum, using techniques such as coulometry, amperometry, and potentiometry. The sensor includes a working electrode and a counter electrode, and can include an insertion monitoring trace to determine correct positioning of the sensor in a connector. In one embodiment, the sensor determines the concentration of the analyte by discharging an amount of charge into the sample, determining the time needed to discharge the charge, and determining the current used to electrolyze a portion of the to analyte using the amount of charge and the amount of time.

Abstract: The invention proposes a sensing element which serves to determine the concentration of oxidizable constituents in a gas mixture, in particular of hydrocarbons, NO, and NH3. Electrically conductive spinels of the general formula ABB′O4, or electrically conductive pseudobrookites of the general formula ABB′O5, serve in this context as the material for the measurement electrode.

Abstract: A device for measurement of an odor component in a sample gas prepares many target gases to be actually measured by a plurality of sensors with different response characteristics, each containing the odor component at a different concentration. Detection signals from these sensors are analyzed by a method of multivariate analysis such as the principal component analysis, and the odor component is characterized on the basis of such an analysis. For preparing the target gases, the sample gas containing the odor component is passed through a collector tube containing an adsorbent which adsorbs this odor component at normal and subnormal temperature and desorbs it when heated. After a specified amount of the odor component is adsorbed to the adsorbent, the tube is heated and an inert gas serving as carrier gas is passed through such that the desorbed odor component is carried to the detectors as a target gas.

Abstract: Method and apparatus for detecting and/or determining ethanol in fluid samples using a substantially non-porous barrier of un-plasticized polyvinyl chloride (PVC) interposed between the sample to be analyzed and a detecting means responsive to ethanol. The ethanol diffuses through the barrier membrane and then is measured at the detecting means. The PVC membrane can be made by solvent casting, and is usually 10 to 40 um thick. Measurement can be by any known means, but preferably electrochemically (amperometrically). The PVC membrane may be part of a multiple membrane system. The method and sensor are useful for analyzing alcoholic liquors or beverages (for example beer, wine and other fermentation products), in their final form or at intermediate stages of their manufacture or storage, and also for the monitoring of a wide range of process, waste and effluent liquids.

Abstract: Chemical sensors for detecting the activity of a molecule or analyte of interest is provided. The chemical sensors comprise and array or plurality of chemically-sensitive resistors that are capable of interacting with the molecule of interest, wherein the interaction provides a resistance fingerprint. The fingerprint can be associated with a library of similar molecules of interest to determine the molecule's activity.

Abstract: A method of measuring oxygen and/or the air-to-fuel lambda ratio and hydrocarbons and/or carbon monoxide in gas mixtures using a gas sensor is provided. To reliably measure a plurality of gaseous components, the sensor is provided with a reference electrode representing a constant oxygen partial pressure, an oxygen ion-conducting solid electrolyte, and at least two measuring electrodes, the measuring electrodes and the reference electrode being mounted directly on the solid electrolyte and having electrical leads for connection and for take-away of electrical measurement signals. The solid electrolyte is constructed with a measurement gas side exposed to the gas mixture and a reference gas side separated from the gas mixture.

Abstract: A gas sensor which can detect the concentration of a combustible gas component in a measurement gas with high accuracy even when the oxygen concentration of the measurement gas or the element temperature changes and which has an excellent response in detecting the combustible gas component is disclosed. In a gas sensor 1, the oxygen concentration of a measurement gas is adjusted to a predetermined level within a first processing space 9 through operation of a first oxygen pump element 3. The measurement gas having an adjusted oxygen concentration is then introduced into a second processing space 10, where a combustible gas component is burned through the assistance of electrodes 16 and 17 functioning as oxidation catalyst sections. Constant voltage is applied to a combustible gas component concentration detection element 5.

Abstract: A gas sensor includes a first processing chamber 3 into which a gas under measurement is introduced through a first gas passage 2; a second processing chamber 5 into which the gas is introduced from the first processing chamber 3 through a second gas passage 4 and in which combustible gas components burn; a third gas passage 15 for introducing O2 into the second processing chamber 5 under diffusion resistance; oxygen pump element 12 adapted to pump out O2 from or pump into the first processing chamber 3 on the basis of an output from an oxygen-concentration sensor 13, which senses the oxygen concentration of the gas introduced into the second processing chamber 5, to thereby control the oxygen concentration of the gas; and a second oxygen pump including a second inner electrode 10 and a second outer electrode 11 formed on an oxygen-ion conductor 1 in such a manner as to face the interior and exterior, respectively, of the second processing chamber 5, and adapted to pump out O2 which remains unconsumed in burn

Abstract: The invention relates to a method of determining the extent to which a milk line system is rinsed with a cleaning fluid, whereby in one or more places in the milk line system the electric conductivity of the cleaning fluid is determined. More in particular, according to the invention, the electric conductivity is measured in places which are difficult to reach for the cleaning fluid and/or in places in the milk line system which are more susceptible to contamination.

Abstract: A method and arrangement is described for determining oxidizable constituents in a gas mixture by using a solid electrolyte cell with at least one reference electrode and at least one working electrode made of electrically conducting mixed oxides which is sensitive to the oxidizable constituents, with the current between the reference electrode and the working electrode induced by electrochemical oxidation of a gas constituent to be determined being measured.

Abstract: An analyte concentration sensor that is capable of fast and reliable sensing of analyte concentration in aqueous environments with high concentrations of the analyte. Preferably, the present invention is a methanol concentration sensor device coupled to a fuel metering control system for use in a liquid direct-feed fuel cell.

Abstract: Improvements to non-acid methanol fuel cells include new formulations for materials. The platinum and ruthenium are more exactly mixed together. Different materials are substituted for these materials. The backing material for the fuel cell electrode is specially treated to improve its characteristics. A special sputtered electrode is formed which is extremely porous.

Abstract: The present invention relates to a limiting-current type hydrocarbon sensor comprising a solid-electrolytic layer made of a Ba—Ce-based oxide, and provides a sensor capable of stably detecting hydrocarbon at high sensitivity, regardless of the concentration of oxygen in an atmosphere. A material mainly containing Al is used for at least one of two electrodes on the solid-electrolytic layer made of a Ba—Ce-based oxide to block oxygen at the electrode, i.e. cathode, whereby a hydrocarbon sensor being stable, high in sensitivity, compact, easy to use and low in cost can be provided. Furthermore, the other electrode, anode, of the limiting-current type hydrocarbon sensor is made of a material mainly containing Ag.

Abstract: A method and apparatus uses a flow injection technique for rapidly and accurately determining the level of one or more additives such as antioxidants and/or antiwear agents in a hydrocarbon fluid such as an engine oil. The hydrocarbon fluid is injected into a mobile phase using a microemulsion or organic solvent as the mobile phase and pumped through an electrochemical detection sensor. The electrochemical detention sensor accurately and quickly provides a sharp signal identifying the electroactive species in the hydrocarbon fluid.

Abstract: A chemical sensor (1) for selectively detecting an analyte in a solution as described. The sensor comprises a flow-through chamber (2), a selective membrane (3), a transducer means (4), an inlet (5) for a liquid flow containing a recognition element, and an outlet (6). There is also described a method of selectively detecting an analyte in a solution, wherein a recognition element is contacted with the solution containing the analyte via a selective membrane, said contact resulting in a response detectable by transducer means. The recognition element is injected into a flow, the flow is passed into a flow-through chamber comprising a transducer means and the selective membrane, where it is contacted with the analyte passing from the solution outside the selective membrane, whereby the recognition element and the analyte interact to provide a signal which is detected by the transducer means.

Abstract: A method and apparatus for detecting ethanol content of a sample wherein a membrane barrier comprising unplasticized PVC is interposed between the sample and detecting means.

Abstract: A sensor serves to determine the concentration of oxidizable components in a gas mixture, in particular for determining saturated and unsaturated hydrocarbons by measuring the voltage between at least one measuring electrode and a reference electrode. The material for the measuring electrode is based on compounds of the eschynite class, including eschynites, euxenites and samarskites with general formula AB2O6, which have the general empirical formula A1-xB2-yB′y (O,OH,F)6±z and may be partially doped or may have occupancy defects.

Abstract: A method and apparatus for identifying an unknown reactive gas in a carrier gas, utilizing a sensor with a diffusion limited inlet. After a signal is established for the carrier gas, a flow of the mixture of carrier gas and reactive gas is passed to the sensor and a steady state signal S is established. Then, the input to and output from the sensor are closed, and the steady state signal decays as a known volume of reactive gas is consumed. The decay curve of the signal is integrated to produce an integrated response .SIGMA., and the ratio S/.SIGMA. is proportional to the diffusion coefficient for the reactive gas. By comparing this ratio to the ratio for a known reactive gas, the identity of the unknown reactive gas can be determined.

Abstract: A gas sensor 1 including a first processing space 9; a first gas passage 11; a second processing space 10; a second gas passage 13; an oxygen concentration detection element 4; a first oxygen pumping element 3 adapted to reduce the oxygen concentration of exhaust gas introduced into the first processing space 9 within a range such that a water vapor contained in the measurement gas is not substantially decomposed; an oxygen catalyst section 16; and a combustible gas component concentration information generation/output section 5. Also disclosed is a gas sensor system including the above gas sensor and first oxygen pumping operation control means for adjusting the oxygen concentration of the measurement gas introduced into the first processing space within a range such that water vapor contained in the measuring gas is not substantially decomposed.

Abstract: A method and apparatus for measuring ethanol vapor concentration wherein a cell output is plotted with respect to time. The gradient of the steady rate portion of the plot is determined and an ethanol vapor concentration signal is generated from the determined gradient.

Abstract: There is provided a concentration sensor for measurement of concentrations of one or plural target substances in a system, with a detection electrode of conductive diamond. The measuring method with the concentration sensor involves measuring the reaction potentials of plural target substances in a sample containing and determining the concentrations of the plural substances by use of the difference between the resulting reaction potentials of the respective substances. The measuring method can also determine the concentration of a single substance in a sample containing one kind of target substance.

Abstract: An electrochemical hydrocarbon sensor and materials for use in sensors. A suitable proton conducting electrolyte and catalytic materials have been found for specific application in the detection and measurement of non-methane hydrocarbons. The sensor comprises a proton conducting electrolyte sandwiched between two electrodes. At least one of the electrodes is covered with a hydrocarbon decomposition catalyst. Two different modes of operation for the hydrocarbon sensors can be used: equilibrium versus non-equilibrium measurements and differential catalytic. The sensor has particular application for on-board monitoring of automobile exhaust gases to evaluate the performance of catalytic converters. In addition, the sensor can be utilized in monitoring any process where hydrocarbons are exhausted, for instance, industrial power plants. The sensor is low cost, rugged, sensitive, simple to fabricate, miniature, and does not suffer cross sensitivities.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: The invention relates to an electrode material for potentiometric or amperometric electrochemical sensors with the chemical composition Ln.sub.1-2 A.sub.1-x B.sub.x O.sub.3, where Ln is at least a lanthanide cation or a mixture of rare earth cations, A is at least a trivalent transitional material, and B is at least a trivalent or bivalent redox-stable cation.

Abstract: A sensor array for detecting an analyte in a fluid, comprising at least first and second chemically sensitive resistors electrically connected to an electrical measuring apparatus, wherein each of the chemically sensitive resistors comprises a mixture of nonconductive material and a conductive material. Each resistor provides an electrical path through the mixture of nonconductive material and the conductive material. The resistors also provide a difference in resistance between the conductive elements when contacted with a fluid comprising an analyte at a first concentration, than when contacted with an analyte at a second different concentration. A broad range of analytes can be detected using the sensors of the present invention.

Abstract: A gas concentration detector using solid electrolyte layers laminated measures a concentration of gas constituents in measuring gas such as exhaust gas of an internal combustion engine without being influenced by oxygen concentration in the measuring gas. The measuring gas is introduced into an inner cavity of the detector and outside air as a reference gas is introduced into an air passage in the detector. Oxygen concentration in the measuring gas in the inner cavity is maintained at a predetermined level by operation of an oxygen pumping cell constituted by an ion conductive solid electrolyte layer and a pair of electrodes formed on both surfaces of the layer. The oxygen concentration in the inner cavity is measured by an oxygen sensor cell having one electrode exposed to the inner cavity and the other electrode exposed to the reference gas.

Abstract: Sinusoidal voltammetry was employed to detect both purine and pyrimidine-based nucleic acids. Adenine and cytosine, representing these two classes of nucleic acids, could be detected with nanomolar detection limits at a copper electrode under these conditions, where the sensitivity for adenine was much higher than that for cytosine. Detection limits for purine-containing nucleotides (e.g., adenosine 5'-monophosphate (AMP), adenosine 5'-diphosphate (ADP), and adenosine 5'-triphosphate (ATP)) were on the order of 70-200 nM using this method. These detection limits are achieved for native nucleotides and are over two orders of magnitude lower than those found with UV absorbance detection. Pyrimidine-based nucleotides could also be detected with high sensitivity due to the presence of a sugar backbone which is electroactive at the copper surface.

Abstract: The invention relates to an electrochemical sensor to determine the concentration of a gas to be quantified, comprising a housing, a measuring electrode comprising a catalystically active material which causes a reaction of the gas to be quantified, a counterelectrode comprising a carbon material, and a solid electrolyte in contact with the measuring electrode and the counterelectrode, wherein the solid electrolyte is prepared by swelling a solid matrix comprising an acrylate polymer with an electrolytic solution comprising at least one acid, and wherein the carbon material in the counterelectrode has a specific surface of at least 40 m.sup.2 /g and comprises reversibly oxidizable or reducible electrochemically active surface compounds.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g. electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery. The probe comprises an integrated membrane-sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s).

Abstract: An electrode characterized by a layer of at least one polymer containing ferrocenylalkyl groups. The electrodes are useful in detecting hydrogen peroxide, organic (hydro)peroxides and lipid hydroperoxides.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: An amperometric sensor device comprising a working electrode, a reference/pseudo-reference electrode and a permselective membrane incorporating a charged organic species. The electrodes are in intimate contact with the membrane and are on a side of the membrane opposite to the side exposed to a fluid sample. The charged organic species provides a conducting path through the membrane between the electrodes.

Abstract: An apparatus or method of the present invention measures carbon monoxide included in a hydrogen-rich reactant gas with high precision, and also measures a lower alcohol or another organic compound included in the reactant gas. A carbon monoxide sensor (1) includes an electrolyte membrane (10), a pair of electrodes (12,14) arranged across the electrolyte membrane (10) to form a sandwich structure, a pair of holders (20,22) for supporting the sandwich structure as well as pair of metal plates (16,18), and an insulating member 24 for connecting the holders (20,22) with each other. A gas flow conduit (28) is joined with one holder (20), and a gaseous fuel is fed to the electrode (12) via the gas flow conduit (28). The electrode (14) supported by the other holder (22) is exposed to the atmosphere. A resistor (34) is connected to detection terminals (20T,22T) of the holders (20,22), and a potential difference between both terminals of the resistor (34) is measured with a voltmeter (32).

Abstract: An apparatus for measuring a combustible gas component of a subject gas in an external subject gas space, including a first processing zone communicating with the subject gas space, 58), a second processing zone communicating with the first processing zone, and a first and a second pumping cell exposed to the first and second processing zones, respectively, each cell including an oxygen ion conductive solid electrolyte layer and a pair of electrodes one of which is exposed to the first or second processing zone, wherein the first pumping cell pumps oxygen out of the first processing zone to control oxygen partial pressure in the first processing zone at a value at which the combustible gas component cannot be burned, while the second pumping cell pumps oxygen into the second processing zone to thereby burn the combustible gas component in the second processing zone, and the concentration of the combustible gas component is determined based on a current flowing or a voltage between the electrodes of the second

Abstract: An apparatus for measuring a combustible gas component of a subject gas in an external subject gas space, including a first processing zone communicating with the subject gas space, a second processing zone communicating with the first processing zone, and a first and a second pumping cell exposed to the first and second processing zones, respectively, each cell including an oxygen ion conductive solid electrolyte layer and a pair of electrodes one of which is exposed to the first or second processing zone, wherein the first pumping cell pumps oxygen out of the first processing zone to control oxygen partial pressure in the first processing zone at a value at which the combustible gas component cannot be burned, while the second pumping cell pumps oxygen into the second processing zone to thereby burn the combustible gas component in the second processing zone, and the concentration of the combustible gas component is determined based on a current flowing or a voltage between the electrodes of the second pump

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: A method for detecting and identifying a chemical substance in various phases such as a vapor phase and a liquid phase. The chemical substance being measured is diffused into a predetermined phase. Then, an electric state at an electrode existing in the predetermined phase is detected as a change with time based on the diffusion and absorption of the chemical substance on the electrode. A pattern of the change of the electric state with time is prepared. A fitting function based on the pattern is set and parameters of the chemical substance being measured are found. A distance between the parameters of the chemical substance being measured and parameters of the reference substance which is detected is determined.

Abstract: An electrochemical gas sensor with at least two electrodes, with an electrode holder and with an electrolyte in a housing made of an electrolyte-impermeable material is improved in terms of its ease of handling and durability, without compromising the quality of the measurement. The otherwise closed housing has only one inlet capillary and outlet capillary each for the gas to be measured. A heater is provided which forms a gap with the working electrode arranged above the inlet and outlet capillaries. The heater is arranged in the housing in the flow path between the inlet and outlet capillaries. The gas sensor may be designed in the form of a miniaturized, chip-like component.

Abstract: A method for detecting organic molecules such as benzene, xylene, ethylbenzene and toluene present in trace quantities in aqueous solutions is provided. The method uses a zeolite having a multiple cage structure, specifically cages of two different volumes. The zeolite is chosen so that the organic molecules are able to access the zeolite on the basis of size. The small cages contain electroactive ions therein and the larger cages contain electroinactive counter cations therein. An aqueous liquid sample to be tested for small molecules is flowed into contact with the zeolite whereby at least some of the electroactive ions in the small cages are released into the aqueous liquid sample by small molecules entering the larger cages and coupling with the electroactive ions in the smaller cages and exiting the zeolite.

Abstract: For identifying one of a plurality of known gases in a gaseous mixture ba on air a single catalytic transducer is placed in the gaseous medium. The catalytic transducer is heated to a lower threshold temperature at which the oxidizable gas is oxidized little or not at all and a first value of a parameter characteristic of the thermal state of the transducer is captured. The catalytic transducer is then heated to an upper threshold temperature at which the oxidizable gas oxidizes significantly in contact with the catalytic transducer and a second value of the parameter characteristic of the thermal state of the transducer is captured. Using a predetermined law, a response signal representative of the gaseous medium is produced from the difference between the second and first values of the parameter characteristic of the thermal state of the catalytic transducer. The catalytic transducer is allowed to cool below the lower threshold temperature and the above operations are repeated cyclically.

Abstract: Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g. electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance.

Abstract: A method is provided for measuring the concentration of a sample gas in an oxygen-containing carrier gas by continuously flowing the oxygen-containing carrier gas which also contains the sample gas whose concentration is to be measured, into and through a central, solid electrolyte inner detector tube, having a particular configuration to eliminate back-diffusion of air thereinto, the inner detector tube having an internal electrode, provided with a first, electrically-conductive output lead, in contact with its interior surface, and an external electrode, provided with a second, electrically-conductive output lead, in contact with its external surface. This bathes a first interface comprising the internal electrode and the interior of the inner detector tube with only the continuously flowing oxygen-containing carrier gas, at a predetermined temperature.

Abstract: An electrochemical sensor for remote detection, particularly useful for metal contaminants and organic or other compounds. The sensor circumvents technical difficulties that previously prevented in-situ remote operations. The microelectrode, connected to a long communications cable, allows convenient measurements of the element or compound at timed and frequent intervals and instrument/sample distances of ten feet to more than 100 feet. The sensor is useful for both downhole groundwater monitoring and in-situ water (e.g., shipboard seawater) analysis.

Abstract: A redox electrode for the rapid detection of glucose in aqueous media and a method for its use are provided. The redox electrode comprises an electrically conductive member such as copper, and a redox membrane in direct contact with said electrically conductive member. The redox membrane comprises a polymer matrix such as PVC containing a plasticizer, and a complex of 7,7,8,8-tetracyanoquinodimethane and tetrathiafulvalene with the complex having a burgundy-red coloration and characterized by a broad absorption from about 340 nm to about 550 nm and weaker absorption between about 650 nm to about 800 nm having about six small peaks with an absorption maximum at about 750 nm. Glucose is rapidly assayed by bringing the redox electrode and a reference electrode into simultaneous contact with an aqueous medium containing KCl, phosphate buffer, glucose oxidase, peroxidase, and 3,3',5,5'-tetramethylbenzidine dihydrochloride. The potential of the redox membrane is then monitored until it is stable.

Abstract: A method for detecting a nitrosothiol in an eluant from a chromatographic process including passing the eluant through a series of electrodes comprising an upstream working electrode and a downstream working electrode. The upstream working electrode is maintained at a potential adequate to reduce the nitrosothiol to a corresponding thiol. The downstream electrode is maintained at a potential to detect the corresponding thiol.

Abstract: The invention is directed to a method for determining characteristic variables of an electrochemically convertible substance in a gas sample. The component of the substance in the gas sample is determined by integrating the total area I enclosed between a physical measurement variable i(t) and a reference line 1. The method is improved in that the concentration portion of the substance can be determined with a high long-term stability and an identification of the substance is possible. The method is carried out by determining the characteristic variables from an individual or several component integrals (I.sub.1, I.sub.2, I.sub.3) as component areas of the total area I and/or of the sum of the component integrals and/or of the ratio of the component integrals I.sub.1 /I.sub.2 and/or of the ratio of the maximum value i.sub.max and the component integral I.sub.2.

Abstract: A novel, inexpensive sensor (10) for detecting volatile hydrocarbons and other solvent vapors detects leaks in the fittings and valves of petroleum refineries and chemical manufacturing and processing plants. The sensor comprises (a) a dielectric substrate (12) having a major surface; (b) a pair of interdigitated, electrically conductive electrodes (14a, 14b) disposed on the major surface of the substrate; and (c) a composite coating (16) covering the interdigitated electrodes and comprising (1) a conductive polymer, and (2) a dielectric polymer with an affinity for the solvent vapors to be detected.