Abstract: Diluents and methodologies for determining the concentration of total calcium in a clinical sample (e.g. whole blood, sera plasma urine cerebro spinal fluid) containing protein-bound calcium are disclosed. Methodologies include the steps of: (a) admixing the sample with a diluent, the diluent including effective amounts of a pH buffer and at least two agents capable of complexing free calcium in the sample, where the agent-calcium complex association constants ("log K" in base 10) each have a range from about 1.5 to about 7.0; and (b) contacting an aliquot of the diluted sample with a calcium-specific ion selective electrode. The response of the calcium-specific ion selective electrode is an indication of the concentration of total calcium in the sample.

Abstract: A method of detecting the presence or measuring the concentration, of a reactive gas in an inert ambient gas by (i) placing a silicon dioxide film derived from the oxidation of a hydrogen silsesquioxane resin in the inert ambient gas; (ii) passing the inert ambient gas over the film; (iii) monitoring a change in the current flow through the film at a voltage below and above a threshold voltage, as an indication of the presence in the inert ambient gas of a reactive gas; and (iv) determining the threshold voltage of the film as a measure of the concentration of the reactive gas in the inert ambient gas. The silicon dioxide film is characterized by a current-voltage curve which includes both linear and non-linear regions.

Abstract: A biosensor and method for determining the hematocrit level of a whole blood sample using electrochemistry. The biosensor includes working and counter electrodes. A porous membrane is impregnated with an electroactive compound and is spatially displaced from the surface of the electrodes. When a whole blood sample is applied to the porous substrate, a mixture of the electroactive compound and the blood is formed. The mixture settles on the electrodes and a potential difference is applied sufficient to oxidize or reduce the electroactive compound and generate a current. This current can be measured and correlated to hematocrit level.

Abstract: A neural modeling device comprising an electrolyte, a lipid or lipid-impregnated membrane which is situated in the electrolyte and in which an ion pump and an ion channel are buried, and an electrode for transmitting a potential of the lipid or lipid-impregnated membrane as an electrical signal. The ion pump actively transports selected ions in the electrolyte through the membrane from one side to the other side in response to an external stimulus such as light irradiation. When the difference in potential between the opposite sides of the membrane reaches a threshold, the ion channel opens to passively transport selected ions in a direction reverse to the ion transporting direction of the ion pump. When this device is exposed to light, the ion pump actively transports ions to generate a potential in the lipid or lipid-impregnated membrane.

Abstract: The invention relates to synthetic proteins that can be used in in vitro sensing devices to detect the presence of physiologically active substances. The synthetic proteins are mimetic to native ion channels in mammalian systems. The invention also relates to a biosensor comprising a support assembly, a synthetic lipid bilayer containing the active channel protein. Lastly, the invention relates to the use of the biosensor disclosed in the application for the in vitro detection of physiologically active substances including antiseptics, antibiotics, neurotransmittors, and others.

Abstract: A method for monitoring automatically, on-line chloride content in a fluid stream in an oil refinery. Additionally, the present invention provides a method for neutralizing the acids resulting from the chloride in a fluid stream. Pursuant to the method, a fluid sample is collected. To the sample is added a sulfide scavenger that will react with the sulfide that is present to create a reaction product. The fluid is then passed to a reaction or measurement cell including a chloride specific electrode. Prior to contacting the chloride specific electrode, the fluid must pass through a membrane that prevents the reaction product from flowing therethrough. The fluid that flows through the membrane is allowed to contact the chloride specific electrode. This allows the chloride content to be monitored in the fluid. The concentration of chloride can then be used to generate a signal to control the addition of a neutralizing agent to the fluid stream.

Abstract: A gas sensor has a gas-sensing component which changes color and/or conductivity on exposure to certain gases, which component comprises a (mono, di or tri) azatetrabenzoporphyrin. Certain (mono, di or tri) azatetrabenzoporphyrins containing a transition metal ion selected from chromium (III), vanadyl, manganese, cobalt or iron (III) are novel.

Abstract: A selective chemical species detector including a conductive polymer based sensing element having a detectable characteristic, for example, the polymer resistivity, permanently altered on exposure to a first chemical species and not permanently altered on exposure to a second chemical species. The detector then determines a permanent change in the detected characteristic and indicates the presence of a chemical species on detection of a such a permanent characteristic change. Also disclosed is a method of fabricating such a sensing element to achieve the desired selectivity.

Abstract: A system for accurate and precise measurements of analyte(s) in a system. The measurement system comprises piezoelectric surface wave sample devices, at least one piezoelectric surface wave reference device, and the measurement instrument.

Abstract: A method and apparatus for measuring the amount of residual chlorine in solution with enhanced accuracy. The basic measurement technique involves introducing a solution of iodide ion into the sample to reduce the chlorine, thereby producing a proportionate amount of iodine; measurement of the iodine concentration is used to infer the initial amount of chlorine. The accuracy of this measurement technique is enhanced by introducing a sufficient amount of scavenger, preferably finely divided zinc metal, into the iodide solution to react with trace amounts iodine present therein.

Abstract: A sensor suitable for use as a viscosity sensor, a chemically selective sensor, or a chemically specific sensor. The sensor is a surface transverse wave (STW) or Love Wave device that, for solute concentration measurements, includes a chemically reactive layer selected to react with the solute to be measured. The surface trapping structure in this device can include dielectric material either as a protective coating or as the core material of the surface trapping structure. The substrate material and cut are selected so that only shear horizontal acoustic waves are produced. Nonpiezoelectric portions of this device can be utilized in the region in which chemicals react the sensor and/or in the region in which energy is converted between electrical and acoustical forms.

Abstract: An apparatus for sensing chemicals over extended range of concentrations. In particular, first and second sensors each having separate, but overlapping ranges for sensing concentrations of hydrogen are provided. Preferably, the first sensor is a MOS solid state device wherein the metal electrode or gate is a nickel alloy. The second sensor is a chemiresistor comprising a nickel alloy.

Abstract: A method for the selective detection of liquid phase hydrocarbons in the C.sub.6 -C.sub.16 range includes a matrix comprising a silicone polymer having dispersed therein a conductive carbon black filler of high structure and comprises signaling the presence of hydrocarbon liquid phase when the electrical resistivity of the sensor increases to a preselected threshold level intermediate the vapor and liquid phase resistivities.

Abstract: A conductive sensor and its use in a diagnostic assay are disclosed. The miniaturized conductive sensor, utilizing a conducting polymer, is used in a diagnostic device to determine the presence or concentration of a predetermined analyte in a liquid test sample, wherein the predetermined analyte, like glucose, is assayed by an oxidase interaction. The interaction between the oxidase and a small amount of the predetermined analyte in the test sample generates, either directly or indirectly, a dopant compound in a reaction zone of the conductive sensor. The dopant compound then migrates to the detection zone of the conductive sensor of the diagnostic device to oxidize the conducting polymer and convert the conducting polymer from an insulating form to a conducting form. The resulting increase in conductivity of the conducting polymer is measured, then the conductivity increase is correlated to the concentration of the predetermined analyte in the test sample.

Abstract: NO.sub.2 and other electron acceptor gases can be detected at 5 volume parts per million by tetrathiafulvalene TTF. The TTF may be incorporated in a polystyrene film, which changes its infra-red spectrum and conductivity upon exposure to such gases.

Abstract: A method for evaluating surface micro roughness of a silicon substrate includes the steps of soaking the silicon substrate in a mixture of hydrochloric acid of 30 to 40 vol %, hydrogen peroxide solution of 30 to 40 vol % and deionized water whose volume ratio is approximately 1:1:16.7, and measuring an amount of chlorine element incorporated into native oxide film on the silicon surface through the soaking process to evaluate the degree of the micro roughness on the silicon substrate surface.

Abstract: A highly sensitive and selective sensor for the detection of halogenated compounds comprises a bead of sodium lanthanum fluoride silicate, having the molecular formula NaLa.sub.4 (SiO.sub.4).sub.3 F, in which are embedded two noble metal electrodes, preferably a straight platinum wire near the center and a helical platinum wire near the periphery of the bead. A current passing through the helical wire maintains the sensor temperature at about 550.degree. C. by resistive heating. The electrical resistance between the two wires is deduced from measurements of the current passing through a fixed external resistor when a substantially constant voltage, preferably about 4 volts, is applied between the wires. A decrease in the measured resistance is an indication of the presence of a halogenated compound in the sample of air to which the bead is exposed. The sensor is preferably controlled by a microprocessor or microcomputer that also performs data processing.

Abstract: A method and apparatus for using a coated piezoelectric crystal to monitor and report corrosion in terms recognized as conforming to an industry standard is disclosed. The present invention provides a method of and system for monitoring corrosion in a corrosive atmosphere, comprising and carrying out the steps of exciting in the atmosphere a crystal, coated with a corrodible metallic substance and having a known vibration frequency; measuring the change in the frequency of vibration resulting from corrosion of the corrodible substance during each of a plurality of intervals of time, including a reference interval and at least one subsequent measurement interval; generating a thickness signal representing the thickness of corrosion corresponding to the measured change in frequency during the measurement interval; and converting the corrosion thickness signal for the measurement interval to a reference signal representing the thickness of corrosion accumulated during the reference interval.

Abstract: Disorders of the base sequences in genomic substances such as DNA and RNA are detected by changing the state of aggregation of fine particles by cleavaging using a nuclease. A single-stranded denatured product of the objective genomic substance is added to first and second fine particles each attached to plural pieces of first and second single-stranded nucleic acid probes, respectively. The first and second single-stranded nucleic acid probes are complementary to a first region and a second region, respectively, on the objective genomic substance, which are exclusive of each other and contiguous from each other. Aggregations of the first and second fine particles are formed by double or multiple hybridization reaction of the denatured objective genomic substance added with the first and second single-stranded nucleic acid probes.

Abstract: Systems are disclosed which utilize implanted glucose sensitive living cells to monitor blood glucose levels. The implanted cells produce a detectable electrical or optical signal in response to changes in glucose concentration in surrounding tissue. The signal is then detected and interpreted to give a reading indicative of blood glucose levels. Capsules containing glucose sensitive cells and electrodes for detecting electrical activity are also disclosed. Method of monitoring blood glucose are also described utilizing the systems and capsules disclosed.

Abstract: A sensor (11, 12, 13, 15) suitable for use as a viscosity sensor, a chemically selective sensor, or a chemically specific sensor. The sensor (11, 12, 13, 15) is a surface transverse wave (STW) device that, for solute concentration measurements, includes a binding layer (18) selected to bind to the solute to be measured. This binding layer (18) can be an antibody so that the sensor detects a particular antigen.

Abstract: Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material.

Abstract: A method for analyzing water or other liquid, in particular rain water, comprises the steps of providing a collector comprising at least first and second volumetric cells and a mechanism for causing water to flow selectively into the cells and for causing water to flow selectively from the cells. Water is caused to flow into a first one of the cells while it is prevented from flowing into the other one of the cells. The water collected in the first cell is caused to flow to a property determining cell when the first cell has been filled to a predetermined volume, and simultaneously water is prevented from flowing into the first cell while it is now permitted to flow into the second volumetric cell. The water collected in the second cell is then permitted to flow to a property determining cell when the second cell has been filled to a predetermined volume, and simultaneously the water is prevented from flowing to the second cell while it is now permitted to flow to the first cell.

Abstract: A device for detecting the presence of a predetermined reactant in a fluid suspected of containing the same which comprises a pyroelectric film having a first and a second surface, a first electrode in contact with a portion of the first surface of said pyroelectric film, a second electrode in contact with a portion of the first surface of said pyroelectric film, said first and said second electrodes being proximate to but electrically insulated from each other, an infra-red transparent third electrode having a first and second surface, said first surface being in contact with the second surface of said film, methods of making such a device and methods of utilizing same.

Abstract: A method of gathering a library of response patterns for one or more sensor arrays used in the detection and identification of chemical components in a fluid includes the steps of feeding samples of fluid with time-spaced separation of known components to the sensor arrays arranged in parallel or series configurations. Modifying elements such as heating filaments of differing materials operated at differing temperatures are included in the configurations to duplicate operational modes designed into the portable detection systems with which the calibrated sensor arrays are to be used. The response patterns from the known components are collected into a library held in the memory of a microprocessor for comparison with the response patterns of unknown components.

Abstract: Air containing water-soluble oxidizing agents, usually predominantly hydrogen peroxide, is exposed in concurrent flow to water that may be acidified if the air contains interfering acidic reducing agents such as sulfur dioxide. After that exposure the gas is separated from the liquid and, if the stripping liquid has been acidified, it is then neutralized. The neutral stripping liquid containing the oxidizing agents is mixed and then reacted with an iodide solution in the presence of a catalyst, after which the reaction products are passed, as the cathode solution, through an electrochemical concentration cell which has an anode chamber filled with a concentrated iodide solution as an anode solution.

Abstract: A selected component of a fluid mixture, for example a reduced sulfur compound vapor in air, is detected by selectively adsorbing the component onto a conductive thin layer of material having a chemical affinity for such component and observing the resultant change of electrical resistivity of the layer. The sensitivity of the detector changes with accumulation of the component on the sensor. The accumulation of the component on the sensor is removed by oxidizing and evolving the component from the sensor to restore the sensor to a linear operating region. The accumulated component is preferably oxidized by reacting the component with ozone. The dynamic range of the sensor is increased by counteracting the tendency for the component to accumulate by continuously feeding back ozone to or controlling the temperature of the sensor so that the sensor operates in a linear region near null.

Abstract: A sensor having an interdigitated gate electrode field effect transistor (IGEFET) coupled to an electron beam evaporated copper phthalocyanine thin film is used to selectively detect parts-per-billion concentration levels of atmosphere contaminants such as nitrogen dioxide (NO.sub.2) and diisopropyl methylphosphonate (DIMP). The sensor is excited with a voltage pulse, and its time- and frequency-domain response are examined. The envelopes of the magnitude of the normalized difference frequency spectrums reveal features which unambiguously distinguish the NO.sub.2 and DIMP exposures.

Abstract: There is disclosed a portable apparatus and process for using same including a test conduit assembly and related conduit valve and fluid flow assemblies for conecting to a process unit for fluid flow communication with the test conduit assembly for passing a fluid to be evaluated for corrosive effect on such test conduit assembly wherein the test conduit assembly includes a test conduit of a predetermined length disposed in a transparent conduit section for passing the fluid therethrough and wherein a heating unit of a predetermined length is disposed in the test conduit wherein the heating unit is of a length of at least about 2 inches and comprises less than about 50 percent of the predetermined length of the test conduit.

Abstract: Apparatus for detecting the level of ammonia in air comprises a conduit through which air is flowed as an airstream past two ammonia sensors that straddle an ammonia absorber. The apparatus also comprises a signal processing circuit for comparing signals generated by the two ammonia sensors with the difference representing the level of ammonia present in the air.

Abstract: An industrial process oxygen analyzer, and method of using same, incorporates an automotive oxygen sensor to minimize the criticalness of controlling heater temperature during operation. Higher sensor heater temperature, required to accommodate the automotive oxygen sensor, is achieved by application of higher supply voltage to the sensor heater. Current limiting of the heater supply circuit reduces stress on the sensor heater, even at the higher operating temperature.

Abstract: Several types of new microelectronic devices including diodes, transistors, sensors, surface energy storage elements, and light-emitting devices are disclosed. The properties of these devices can be controlled by molecular-level changes in electroactive polymer components. These polymer components are formed from electrochemically polymerizable material whose physical properties change in response to chemical changes, and can be used to bring about an electrical connection between two or more closely spaced microelectrodes. Examples of such materials include polypyrrole, polyaniline, and polythiophene, which respond to changes in redox potential. Each electrode can be individually addressed and characterized electrochemically by controlling the amount and chemical composition of the functionalizing polymer. Sensitivity of the devices may be increased by decreasing separations between electrodes as well as altering the chemical environment of the electrode-confined polymer.

Abstract: Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising (a) a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, operatively coupled to (b) a transducer capable of directly converting said expansion or contraction to a measurable electrical response.

Abstract: The apparatus employs a method for accurate, reproducible analytical solution evaluation eliminating the need for a reference sensor by determining the activity of selected species employing species specific sensors and species combination sensors in conjunction with Nernst-type equations. The apparatus includes sensor structures for elimination of edge effects to signals thereby yielding accurate, reproducible measurements, and a cartridge structure adapted to incorporate an array of the new sensors for employment of the new method where the cartridge is particularly adapted for miniaturization, maintaining a fixed volume of solution for analysis and providing an anaerobic testing environment. Lastly, a compact instrument embodying miniaturization especially adapted for field use and use of the cartridge is provided herein.

Abstract: An electrical biosensor for analyte determination is prepared by polymerization of a mixture of a biological receptor capable of binding an analyte in a sample, a protein and a polymerizing agent such as glutaraldehyde to form a polymeric film on a transducer. The mixture preferably contains a stabilizer selected from lipids, detergents and antioxidents. The receptor may be an acetylcholine receptor and the analyte, acetylcholine. A preferred stabilizer is a combination of phosphatidyl choline and octyphenoxypolyethoxyethanol. In carrying out a determination, analyte in a sample binds to the receptor causing a change in an electrical characteristic of the film which is indicative of the presence of the analyte. The biosensor may contain a second polymeric film that is free of the receptor and which serves as a control.

Abstract: The present invention provides a method of using a thermal shock probe, such a thermal shock probe and application of this method to the control of a heat pump. The method of using a thermal shock probe formed of a thermocouple associated with a heating element, is characterized in that it is used for monitoring, in a solid-gas reactor (1,2), the chemical reaction between a porous mixture and a gas by applying a heat flux variation and processing the response of the thermocouple.

Abstract: The invention relates to a measuring apparatus for analyzing a gas mixture for at least one gas contained therein in a very low concentration. Such a gas can, for example, be anesthesia gas in ambient room air. The invention is directed to a type of apparatus wherein the gas mixture is split up into conversion products with a heated catalyzer element during measurement and wherein the conversion products are detected by means of a gas sensor which takes up at least one of the conversion products. The measuring apparatus makes possible a quasi-continuous monitoring of the ambient room air for an anesthesia gas with the aid of such sensors. In order to make this possible, a sequence of measuring phases and regeneration phases are cyclicly repeated. The measuring phases are very short in relationship to the response time of the sensor.

Abstract: Procedure and apparatus for the continuous analysis of the chloride ion content of overhead waters downstream of a hydrocarbon distillation column for more effectively preventing hydrochloric acid corrosion of downstream equipment while avoiding over-neutralizing the overhead waters to the detriment of the hydrocarbon product. This procedure comprises the following operations, in the order given or in a different order:Drawing from the overhead waters a stream of water for analysis;removing from the sample so drawn the hydrocarbons as well as the suspended matter;blowing nitrogen into the sample to sweep away the hydrogen sulfide ans the residual hydrocarbons;oxidizing the S.sup.2- or HS.sup.- sulfide ions to sulfate ions;acidifying the sample;finally, measuring by ionometry, and more particularly by means of a combined electrode, the content of chloride ions present.

Abstract: Several types of new microelectronic devices including diodes, transistors, sensors, surface energy storage elements, and light-emitting devices are disclosed. The properties of these devices can be controlled by molecular-level changes in electroactive polymer components. These polymer components are formed from electrochemically polymerizable material whose physical properties change in response to chemical changes, and can be used to being about an electrical connection between two or more closely spaced microelectrodes. Examples of such materials include polypyrrole, polyaniline, and polythiophene, which respond to changes in redox potential. Each electrode can be individually addressed and characterized electrochemically by controlling the amount and chemical composition of the functionalizing polymer. Sensitivity of the devices may be increased by decreasing separations between electrodes as well as altering the chemical environment of the electrode-confined polymer.

Abstract: A portable system for analyzing a fluid sample includes a small, portable, low-pressure and low-power chromatographic analyzer and a chemical parameter spectrometry monitor including an array of sensors for detecting, identifying and measuring the concentrations of a variety of components in the eluent from the chromatographic analyzer. The monitor includes one or more operating condition controllers which may be used to change one or more of the operating conditions during exposure of the sensors to the eluent from the chromatography analyzer to form a response pattern which is then compared with a library of previously established patterns. Gas and liquid chromatographic embodiments are disclosed. In the gas embodiment, the operating condition controllers include heated filaments which may convert electrochemically inactive components to electrochemically active products. In the liquid chromatography embodiment, low-power, liquid-phase equivalents of heated filaments are used with appropriate sensors.

Abstract: A method for determining the concentrations of total calcium and at least one monovalent ion in a sample includes the steps of mixing the sample with a diluent that has a pH within the range pH 6.5 to 7.0 and includes 2-amino-2-hydroxymethyl-1,3-propanediol phosphate and is free of the monovalent ion. An aliquot of the diluted sample is concurrently contacted with a calcium-specific ion selective electrode and an ion selective electrode specifically responsive to the monovalent ion, the response of the calcium-specific ion selective electrode is measured as an indication of the concentration of total calcium in the sample, and the response of the monovalent ion specific ion selective electrode is measured as an indication of the concentration of the monovalent ion in the sample.

Abstract: A differential conductivity sulfate monitor for determining the sulfate concentration of a fluid sample by monitoring the cation conductivity of the fluid sample before and after sulfate has been removed therefrom. The cation conductivities of the fluid sample before and after sulfate has been removed are compared to establish a differential conductivity, and the differential conductivity is used to calculate the sulfate concentration in accordance with a known relationship between a conductivity differential and the sulfate concentration of a fluid sample.

Abstract: Multiple sclerosis and other diseases are diagnosed by first coating a plasm protein-adsorbing surface with a patient's blood plasm protein in an electrolyte fluid, and measuring the streaming potential of the protein-coated surface. Next, a challenge material such as a fatty acid having from 6 to 24 carbon atoms is added to the protein in electrolyte fluid mixture to alter the electro-kinetic potential of the adsorbed blood plasm protein layer. The streaming potential of the altered layer then is measured. The streaming potential results thus obtained are compared with measurements of the streaming potential characteristic of a surface similarly treated, but using normal blood plasma protein.

Abstract: According to the invention a piezoelectric crystal, e.g. a quartz crystal, coated with a metal or another suitable material is exposed to the action of a corrosive liquid, preferably by being immersed therein. The mass change on the crystal surface, caused by the corrosion, and the resulting change in the natural oscillation frequency of the crystal is determined and constitutes a measure of the corrosivity of the liquid. The natural oscillation frequency of the crystal can in this way also be measured in situ in the liquid, in which way the dynamic course of the corrosion reaction can be followed continuously. According to a special embodiment of the invention the sensitivity during the measurement can be increased, if the crystal is pretreated by being activated with a sulphide solution.

Abstract: Disclosed is a process and device for facilitating the differentiation of particles in a medium. The particles, which belong to at least two different groups of particles, are enclosed in a chamber bounded by electrodes which produce a rotating electrical field. A means for producing two rotating electrical fields having opposite directions of rotation and variable rotational frequency is provided to be attached to the electrodes. The particles exposed to the rotating electrical field forces with opposite directions of rotation can be differentiated on the basis of their rotational behavior.

Abstract: This invention introduces a new class of devices for detecting the presence of biological molecules. The construction principle of the device involves the direct introduction of small monomers of macromolecules into the surface layer of a semiconductor, for example by doping at the gate-area of a field effect transistor (or any other similar suitable electronic device, also on carbon basis). There are a few biological monomers which pair specifically enough for a selective measurement, such as nucleotides (or portions thereof, e.g. adenine, thymine, guanine, cytosine and uracil). This invention leads to substantial improvement of biosensors, as there should be: Better signal to noise ratio, and options for: reading of nucleotide sequences, better process control, and new synthesis possibilities (e.g. modified Merrifield Synthesis). The invention also offers the potential to construct cybernetic systems and true biochips.

Abstract: The presence of carbon dioxide contained in a gas can be detected through measurement of the change in the electrical resistance of a hydroxyapatite in contact with carbon dioxide gas. The sensitivity of the hydroxyapatite to carbon dioxide gas can be enhanced by the formation of a composite of the hydroxyapatite with an inorganic carbonate, e.g., sodium carbonate or calcium carbonate. The sensitivity to carbon dioxide gas can be further enhanced by the formation of a composite of the hydroxyapatite with an inorganic halide, e.g., calcium chloride.

Abstract: A process for measuring the relative equilibrium moisture content, particularly of surface samples such as papers, films, woven material or the like, with which the sample is introduced into a hermetically sealable measuring tube and then the equilibrium moisture content arising from a temperature which is predetermined and adjustable by means of a thermostat is measured by a moisture sensor inserted into the measuring tube and not touching the sample. An apparatus serves to carry out the process which has a measuring tube which can be sealed on both sides and can be inserted into a thermostat, in which measuring tube frames are arranged for holding the sample to be examined, and which has a moisture sensor provided at the side sealing the measuring tube.

Abstract: An electrochemical gas sensor is described incorporating a sensing electrode, a reference electrode, a solid matrix containing an alkali salt, a potentiostat and a heater. The invention overcomes the problem of a liquid electrolyte which may operate over limited environmental conditions.

Abstract: An electrochemical measuring system which effects, measures and sorts charge transfer reactions of selected substances in a sample solution is provided. The system includes a novel electrode which is adapted to measure simultaneously on at least two electrodes at least two electrolytic potentials with reference to a reference potential. In a preferred form the electrode comprises a hollow, cylindrical body formed of an electrically insulating material. The electrode is open at least at one end and has a generally smooth cylindrical inner surface. A plurality of electrically discrete active electrode segments are mounted on the inner surface of the electrode with their active surfaces substantially flush with the generally smooth cylindrical inner surface.