Abstract: Disclosed is a method of creating a real-time oxidation-reduction potential signature in a hot water system to detect REDOX stress and inhibit corrosion in the hot water system. The method includes defining one or more operational protective zones in the hot water system. One or more of the operational protective zones includes an oxidation-reduction potential probe that is operable to measure a real-time oxidation-reduction potential in the hot water system at operating temperature and pressure. The probe transmits the measured real-time potential to the controller, which analyzes and interprets the transmitted potential to create an oxidation-reduction potential signature for the hot water system. If the signature does not conform to an oxidation-reduction potential setting, the controller is operable to feed one or more active chemical species into the hot water system.

Abstract: The measuring device has at least one measuring probe, e.g., a physical or electrochemical measuring probe, which is equipped with one or more memory units and which is connected through a cable, e.g., a coaxial cable, to a transmitter which includes a processor. The measuring probe has a ground wire and is connected to the memory unit through a first signal wire, wherein under the control of the processor in accordance with a transmission protocol, the first signal wire and a connecting cable serve for the unidirectional transmission of the analog or digital measuring signal of the measuring probe as well as the preferably bidirectional transmission between the measuring probe and the transmitter of digital operating data which are read from or to be written into the memory unit.

Abstract: A system and method that uses electrical conductivity measurements to identify the impurities in a solution, as well as the concentrations of such impurities. The conductance versus temperature curve for any particular ion is unique to that ion and the conductance versus temperature curve for a solution is unique to the ions in the solution and their concentrations. Equations can be used to describe the conductivity versus temperature curve containing specific ions at set concentrations. To that end, the present invention measures the conductivity of a solution over some specified temperature range, calculates a conductivity-temperature curve from a library of ions to match the measured conductivity, and uses a mathematical process to vary the ions and their concentrations in the calculated curve to make it match the measured curve as closely as possible.

Abstract: An adapter for a potentiometric sensor having a sensor shaft, which has a reference liquid opening in its exterior surface. The adapter comprises an annular chamber member having a sensor opening for receiving the sensor shaft. Arranged in the sensor opening are first and second sealing rings for the sensor shaft. The axial position of the reference liquid opening lies between the first and second sealing rings. Formed between the sealing rings and the sensor shaft is an annular chamber, which is in communication with the reference liquid opening. The annular chamber member further includes a duct extending between the annular chamber and a reference feed opening. The adapter further includes a process connection member having a process connection opening, which surrounds the sensor shaft, and whose axis is aligned with the axis of the sensor opening.

Abstract: An electrochemical sensor is provided that includes a housing defining a cavity for a reference electrolyte and defining an opening to the cavity configured to be proximate to a target fluid. The sensor further includes a junction plug comprising a porous material and a cross member impermeable to a target fluid positioned between the junction plug and the cavity. The cross member includes a planar portion disposed against the junction plug that defines an aperture to enable electrochemical communication between the target fluid and the reference electrolyte.

Abstract: A system automatically maintains at least one of a pH level and a sanitizing agent level of water in a water feature. The system includes a sensor assembly responsive to at least one of a pH level of the water and a sanitizing agent level of the water. The system further includes a controller which generates control signals in response to signals from the sensor assembly. The system further includes at least one of a first source containing a sanitizing agent material and a second source containing a pH-modifying material. The system further includes a third source comprising a valve assembly and a third container containing a liquid calibrant material. The valve assembly is responsive to at least a portion of the control signals from the controller by selectively allowing the calibrant material to flow from the third container through the sensor assembly to the water feature.

Abstract: The present invention is a system for monitoring a patient's breath chemistry comprising a plurality of components, including a self-condensing pH sensor distally mounted on a catheter, a transmitter with hydration sensing circuitry for the pH sensor, and, a processing receiver/data recorder. The specifically designed self-condensing pH sensor located on the distal end of the catheter is designed to be inserted into the patient's airway. Monitoring of a patient's breath pH is accomplished by using the miniaturized self-condensing pH sensor, providing for real-time monitoring of patient airway pH values.

Abstract: A retractable assembly, including an assembly housing and a tubular holder for a sensor guided in the assembly housing via a stroke movement linearly between a first position and a second position, wherein the sensor ascertains a physical and/or chemical process variable in a process, wherein an on-site electronics is provided, which ascertains as an actual value, or values, information concerning at least one other state variable of the retractable assembly, the process and/or the sensor, and wherein associated with the on-site electronics is a memory unit, in which the ascertained actual value, or values, is/are stored and/or predetermined desired values are stored.

Abstract: A system, method and apparatus for determining a physiological condition within a mammal based on pH and/or temperature measurements. In one aspect, the invention is directed to an apparatus for measuring a physiological condition within a mammal comprising: an elongated housing extending along a longitudinal axis from a proximal end to a distal end, the housing having an internal cavity; a transverse wall within the internal cavity; a cutout in the elongated housing forming an opening into the internal cavity and exposing at least a portion of the transverse wall; a pH sensor for measuring pH within a body lumen of the mammal and located on the exposed portion of the transverse wall; a cover having a first opening forming a first passageway through the cover; and the cover secured to the elongated housing so that the pH sensor is exposed via the first opening, the cover covering the cutout so as to hermetically seal the opening into the internal cavity.

Abstract: A signal processing circuit includes an ion sensitive field effect transistor, a reference electrode for the ion sensitive field effect transistor, a metal oxide semiconductor transistor having its gate coupled to the reference electrode, and a biasing circuit. The biasing circuit is configured to bias the ion sensitive field effect transistor and the metal oxide semiconductor field effect transistor to operate in a weak inversion region and to provide an output current signal.

Abstract: It is an object of the present invention to provide a hydrogen quantity sensor that can directly measure hydrogen contained in a hydrogen storage device with simple and easy means. The hydrogen quantity sensor comprises a detecting electrode 30 comprised of a hydrogen storage alloy 18 disposed inside a hydrogen storage vessel 10, a standard electrode 28 disposed to confront the detecting electrode 30; and an electrolyte member 26 disposed between the detecting electrode 30 and the standard electrode 28. The detecting electrode 30, the standard electrode 28 and the electrolyte member 26 constitute a sensor portion 32 to measure hydrogen concentration within the hydrogen storage alloy 18 as an electromotive force value.

Abstract: A plug-in module for a liquid- or gas-sensor comprised of a sensor module (SM) and a sensor module head (SMH), which can be releasably connected together, and which, when connected, enable data and energy transfer via a galvanically decoupled transfer section, wherein the sensor module head (SMH) includes an energy supply unit for operating the sensor module head (SMH) and the sensor module (SM), as well as a data memory (MEM), in order to store sensor data received from the sensor module (SM).

Abstract: A system automatically maintains at least one of a pH level and a sanitizing agent level of water in a water feature. The system includes a sensor assembly responsive to at least one of a pH level of the water and a sanitizing agent level of the water. The system further includes a controller which generates control signals in response to signals from the sensor assembly. The system further includes at least one of a first source containing a sanitizing agent material and a second source containing a pH-modifying material. The system further includes a third source comprising a valve assembly and a third container containing a liquid calibrant material. The valve assembly is responsive to at least a portion of the control signals from the controller by selectively allowing the calibrant material to flow from the third container through the sensor assembly to the water feature.

Abstract: A portable multi-ions sensing system is provided.

Abstract: A method for monitoring a reference half cell, which forms with a measuring half cell a potentiometric measuring point for determining and/or monitoring an ion concentration of a medium. The ion concentration of the mediums determined on the basis of at least one measurement signal determined in a measuring circuit, between the measuring half cell and the reference half cell. According to the invention, the measuring point is operated intermittently in an operating mode and in a test mode, wherein, in the operating mode, the ion concentration is measured and wherein, in the test mode, the proper functioning of the reference half cell is checked.

Abstract: The sensor arrangement includes: a least two sample chambers; at least two potentiometric FET-sensors, especially ISFET-sensors or ChemFET-sensors, having, in each case, a sensitive surface section, wherein each sensitive surface section lies in flow connection with its one of the sample chambers; and a reference cell having a reference medium for providing a reference potential, wherein the sample chambers are connected with the reference medium via an electrolyte bridge. The reference cell has, preferably, a potentiometric reference-FET-sensor for providing a reference potential, which is registered against the pseudo-reference-potential of a redox electrode. The potentials Udiff1, Udiff2, . . .

Abstract: The invention comprises novel apparatuses and testing methods for evaluating a fluid diffusion component. The apparatus includes a fluid capable of undergoing oxidation or reduction, a half-cell electrode assembly able to receive the fluid, and a change in acidity indicator in communication with the assembly. An inventive method of the invention includes the steps of passing a fluid capable of undergoing oxidation or reduction through a half-cell electrode assembly to form a sample, contacting the sample with an indicator, and detecting a change in acidity in the indicator.

Abstract: A measuring device having a plurality of potentiometric electrode pairs situated on a substrate is described. One of the electrodes of each electrode pair represents a reference electrode and the other electrode represents a pH-sensitive working electrode. The electrode pairs form an interdigital structure, and the substrate is covered by a mask in such a way that the individual electrode pairs are separated from one another at least in the area of the interdigital structures of the electrode pairs.

Abstract: A multi-functional PH meter and the fabrication thereof are disclosed. The multi-functional pH meter immediately displays the measurement result on a liquid crystal display and saves in a compact flash card so as to provide portable functionality. In addition, the multi-functional pH meter has data communication functionality with a computer. Finally, the drift and hysteresis software calibration technique is applied. Thus, this method can increase ion detection accuracy and system reliability. The multi-functional pH meter includes a sensor unit, an analog signal processing unit, a microprocessor unit, the liquid crystal display unit, the compact flash card unit and a data transmission unit.

Abstract: A multi-functional PH meter and the fabrication thereof are disclosed. The multi-functional pH meter comprises a sensor unit, an analog signal processing unit, a microprocessor unit, a liquid crystal display unit, a compact flash card unit and a data transmission unit. The sensor unit includes an electrode, a substrate, an indium tin oxide film on the substrate, a sensing film on the indium tin oxide film and connecting to a conductive wire, a package material covering the sensing film, the indium tin oxide film and a portion of the substrate and exposing the sensing film via a sensing window. The analog signal processing unit processes analog signals from the sensing unit via the conductive wire. The microprocessor unit receives the signals from the analog signal processing unit and generates a pH value of a solution being detected. The liquid crystal display unit displays the pH value and the compact flash card unit saves the pH value.

Abstract: The present invention pertains to an apparatus for evaluating the signal strength from the pH sensor to determine whether the sensor is hydrated sufficiently to accurately measure pH. This is accomplished by utilizing circuitry that periodically sends a low voltage signal to a suitable pH sensor and then receiving the resulting waveforms which are analyzed by a processing receiver. The electrical connection between a suitable pH sensor and hydration monitoring circuitry is generally hard wired. In one embodiment, a processing receiver is coupled with the hydration monitoring circuitry as a single apparatus. In a second embodiment, the processing receiver can be independent and located remote from the hydration monitoring circuitry. In this embodiment, the hydration monitoring circuitry and the processing receiver are electrically connected using either hard wired techniques or wireless technology. In addition, the processing receiver can include data recording capability.

Abstract: An oil deterioration detection apparatus includes a sensor, an evaluation circuit, and a malfunction detecting circuit. The evaluation circuit has a determination circuit. The malfunction detecting circuit has a resistor and a switch. The evaluation circuit evaluates a condition of the oil based on a normal voltage. The normal voltage is measured when the switch is opened so that the resistor is not electrically conducted. The determination circuit determines whether the sensor malfunctions based on a relation between the normal voltage and a divided voltage. The divided voltage is measured when the switch is closed so that the resistor is electrically conducted in parallel with the sensor.

Abstract: A self-cleaning oxidation-reduction potential (“ORP”) probe system includes an ORP electrode (11), a flow cell (12) surrounding the ORP electrode, and a plurality of cleaning beads (17) contained in the flow cell in a manner in which they are free to contact the ORP electrode when fluid is passed through the flow cell. The self-cleaning probe system may also or alternatively include a pH probe electrode, or another fluid-testing probe, in the flow cell.

Abstract: A SnO2 ISFET device and manufacturing method thereof. The present invention prepares SnO2 as the detection membrane of an ISFET by sol-gel technology to obtain a SnO2 ISFET. The present invention also measures the current-voltage curve for different pH and temperatures by a current measuring system. The temperature parameter of the SnO2 ISFET is calculated according to the relationship between the current-voltage curve and temperature. In addition, the drift rate of the SnO2 ISFET for different pH and hysteresis width of the SnO2 ISFET for different pH loop are calculated by a constant voltage/current circuit and a voltage-time recorder to measure the gate voltage of the SnO2 ISFET.

Abstract: The invention relates to an internal solution ground for primary use with a pH sensor, and preferably with a multi-sensing instrument monitoring a pH sensor and one or more additional secondary sensors having non-isolated circuits. In one aspect, a pH sensor assembly includes a pH electrode, a reference electrode, and an internal solution ground wire. The internal solution ground wire shares a liquid junction with the reference electrode but is protected by the reference fill solution. In one embodiment, the internal solution ground can be electrically isolated through a capacitor or, alternately, a capacitor and resistor in parallel.

Abstract: A highly sensitive biosensor that uses a smaller amount of sample for measurement is described. The biosensor includes a first insulating base plate having a working electrode, a second insulating base plate having a counter electrode opposed to the working electrode, and a reagent layer containing at least an oxidoreductase. The biosensor further includes a sample supply pathway formed between the first and second insulating base plates, where the working electrode, counter electrode and reagent layer are exposed to an inside of the sample supply pathway, and the distance between the working electrode and the counter electrode is 150 ?m or less.

Abstract: An a-C:H ISFET device and manufacturing method thereof. The present invention prepares a-C:H as the detection membrane of an ISFET by plasma enhanced low pressure chemical vapor deposition (PE-LPCVD) to obtain an a-C:H ISFET. The present invention also measures the current-voltage curve for different pH and temperatures by a current measuring system. The temperature parameter of the a-C:H ISFET is calculated according to the relationship between the current-voltage curve and temperature. In addition, the drift rates of the a-C:H ISFET for different pH and hysteresis width of the a-C:H ISFET for different pH loops are calculated by a constant voltage/current circuit and a voltage-time recorder to measure the gate voltage of the a-C:H ISFET.

Abstract: A method and a device for detecting a deterioration of vehicle oil are disclosed in which the end point of the oil service life can be detected with higher accuracy, while at the same time detecting the progress of the oil condition in the vicinity of the end point of the oil service life. The acidity or basicity of the vehicle oil is measured using a pH sensor (11) generating an output in responding to the degree of the acidity or basicity. The deterioration of the vehicle oil can be detected based on the fact that with the increase in vehicle mileage, a line approximating the output of the pH sensor (11) with respect to the vehicle mileage has a tendency to change from a first inclination to a second inclination larger than the first inclination and then from the second inclination to a third inclination smaller than the second inclination.

Abstract: A symmetrically wired device and a process for measurement of the concentration of ions, especially hydrogen (H+) ions, in a measurement liquid. The device comprises a pH-sensitive measurement electrode, a reference electrode and a comparison electrode, all located in the measurement liquid and which places the measurement liquid at a definable ground reference. The device forms a difference signal referenced to the ground reference from the difference between a measurement signal (?pH) of the measurement electrode and the reference signal (?ref) of the reference electrode. The difference signal is dependent on the ion concentration in the measurement liquid. The device compensates for the noise potential (?chem) arising between the comparison electrode and the measurement electrode by setting a reference potential (?bez) on the comparison electrode, such that ?ref assumes a zero value.

Abstract: An a-C:H ISFET device and manufacturing method thereof. The present invention prepares a-C:H as the detection membrane of an ISFET by plasma enhanced low pressure chemical vapor deposition (PE-LPCVD) to obtain an a-C:H ISFET. The present invention also measures the current-voltage curve for different pH and temperatures by a current measuring system. The temperature parameter of the a-C:H ISFET is calculated according to the relationship between the current-voltage curve and temperature. In addition, the drift rates of the a-C:H ISFET for different pH and hysteresis width of the a-C:H ISFET for different pH loops are calculated by a constant voltage/current circuit and a voltage-time recorder to measure the gate voltage of the a-C:H ISFET.

Abstract: An electrical measurement device is described, with a measurement input, an integrated sensor, a measurement and evaluation circuit, and a measured value display, and several measured value outputs. The electrical measurement device enables not only one measured value or several measured values to be determined, but makes it possible to display and process the determined measured values depending on other values such as comparison values and setpoints. An influencing input acts on the measurement and evaluation circuit and is the connecting point for the electrical measurement device to which or via which an influencing value can be applied or input. Therefore, a value with which the measured value can be influenced in the broadest sense is applied.

Abstract: An oil condition sensor detects a condition of oil in response to the potential difference between electrodes. The electrodes include at least a first and second electrodes coaxially arranged. The electrodes have projections being arranged to face each other in an opposed manner. Therefore, the projections provide wide surface area that performs as electrodes. It is possible to provide compact oil condition sensor that is easy to install into an oil tank or oil pan.

Abstract: A galvanic probe comprises a sensor electrode and a reference electrode. The sensor electrode has an exposed surface that comprises a noble metal or antimony or bismuth, and, optionally, an oxide or hydroxide thereof. The reference electrode is spaced apart from the sensor electrode and has an exposed surface that comprises zinc or magnesium, and, optionally, an oxide or hydroxide thereof. The probe may be incorporated into a device for controlling the pH and/or ORP of a fluid in a vessel to a desired pH and/or ORP level, incorporated into methods for measuring the pH and/or ORP of a fluid, or used as a galvanic cell.

Abstract: An acid concentration continuous measuring apparatus is equipped with the combination of a body having a flow path through which pickling solution contained in a pickling tank is made to continuously pass in a single direction, a density sensor, a temperature sensor, and a conductivity sensor which are installed on the body and substantially continuously measure the pickling solution flowing along the flow path, and a calculating apparatus which calculates the acid concentration of the pickling solution based on the measured results. Feedback control of the hydrochloric acid concentration in a final pickling tank of a plurality of pickling tanks forming a continuous pickling line is performed using the acid concentration continuous measuring apparatus.

Abstract: The invention relates to a device for measuring the concentration of ions, notably of hydrogen ions, in a measuring liquid using at least one ion-sensitive field effect transistor which is integrated into an electric circuit within the device in such a way that said circuit emits an output signal which serves as measure of the ion concentration in the measuring liquid. To provide a circuit which is as simple as possible and in particular comprises as few components as possible, the invention provides for the at least one pH-ISFET to be bridge-connected with at least three resistors.

Abstract: A method and a device for detecting a deterioration of vehicle oil are disclosed in which the end point of the oil service life can be detected with higher accuracy, while at the same time detecting the progress of the oil condition in the vicinity of the end point of the oil service life. The acidity or basicity of the vehicle oil is measured using a pH sensor (11) generating an output in responding to the degree of the acidity or basicity. The deterioration of the vehicle oil can be detected based on the fact that with the increase in vehicle mileage, a line approximating the output of the pH sensor (11) with respect to the vehicle mileage has a tendency to change from a first inclination to a second inclination larger than the first inclination and then from the second inclination to a third inclination smaller than the second inclination.

Abstract: A sensible container for measuring conductive parameters in the liquid and acquiring properties of water in the liquid, consists of: a seat; a cup body installed at the seat, at least one probe being installed at a bottom of the cup body for contacting the liquid for measuring the resistance parameters of the liquid, such as concentration, pH value, salty and sugariness in the liquid; a measuring body at an interior of the seat and electrically connected to the probe for measuring the conductive parameters of the liquid; a display installed at an outer surface of the seat; and connected to the measuring body for displaying the measuring result.

Abstract: The invention relates to an internal solution ground for primary use with a pH sensor, and preferably with a multi-sensing instrument monitoring a pH sensor and one or more additional secondary sensors having non-isolated circuits. In one aspect, a pH sensor assembly includes a pH electrode, a reference electrode, and an internal solution ground wire. The internal solution ground wire shares a liquid junction with the reference electrode but is protected by the reference fill solution. In one embodiment, the internal solution ground can be electrically isolated through a capacitor or, alternately, a capacitor and resistor in parallel.

Abstract: An integrated sensor device having a structure suited for mass production despite of a short lifetime and automatically replaceable, and a measuring system realizing a continuous monitoring at a low cost by using the integrated sensor device are disclosed. The integrated sensor device is constructed into a signal integrated circuit device comprising a sensor unit (6) for measuring a change in the quantity or concentration of a substance; a control unit (7) for processing a signal representing the measurement result; and an antenna unit (10) for transmitting the processed signal to the outside and for receiving an energy necessary for the transmission and the operations of the sensor unit (6) and the control unit (7).

Abstract: In a pair of electrodes where a potential difference is changed in accordance with acidity or basicity of oil, a reference electrode is made of cobalt or a cobalt alloy, and a sensitive electrode is made of tungsten or a tungsten alloy. The sensitive electrode is used in combination with the reference electrode. Accordingly, it is possible to provide a pair of electrodes for detecting the acidity or the basicity of the oil which use a novel electrode material not hazardous to the environment and at the same time, suited for use in a semiconductor fabrication technique.

Abstract: A method and an apparatus for measuring the temperature parameters of an ISFET that uses hydrogenated amorphous silicon as a sensing film, which uses the measurements of the temperature parameters and the source/drain current and gate voltage in an unknown solution to sense the ion concentration and the pH value of the unknown solution.

Abstract: A pH analyzer is operated to measure conductivity of a solution by applying a substantially DC current having peak values, IREF−PEAK, to a reference electrode of an ion-sensitive sensor having an ion-specific electrode in contact with the solution. The reference electrode is coupled to the ion-specific electrode through the solution. The peak voltage, VION−PEAK, between the ion-specific electrode and the common electrode is measured, and the conductivity of the solution is identified based on C SOL = I REF - PEAK V ION - PEAK .

Abstract: The invention relates to a symmetrically wired device and a process for measurement of the concentration of ions, especially hydrogen (H+) ions, in a measurement liquid. The device comprises a pH-sensitive measurement electrode which is located in a measurement liquid, a reference electrode located in the measurement liquid, a comparison electrode which is located in the measurement liquid and which places the measurement liquid at a definable ground reference. Moreover, the device comprises means for forming a difference signal referenced to the ground reference from the difference between a measurement signal (&phgr;pH) of the measurement electrode and the reference signal (&phgr;ref) of the reference electrode. The difference signal is dependent on the ion concentration in the measurement liquid.

Abstract: An oil condition sensor detects a condition of oil in response to the potential difference between electrodes. The electrodes include at least a first and second electrodes coaxially arranged. The electrodes have projections being arranged to face each other in an opposed manner. Therefore, the projections provide wide surface area that performs as electrodes. It is possible to provide compact oil condition sensor that is easy to install into an oil tank or oil pan.

Abstract: A flow cell for a particle analyzer using an electrical sensing zone method, includes: a detecting member having a through hole; a first cell for supplying a particle containing liquid to the through hole; a second cell for receiving and discharging the particle containing liquid that has passed through the through hole; electrodes provided in the first cell and the second cell respectively, for supplying an electrical current to the liquid passing through the through hole; and a sliding member for sliding at least one of the first and second cells to change a distance therebetween; wherein the first and second cells cooperate with the sliding member to detachably sandwich the detecting member therebetween so that the detecting member is connected to the first and second cells in a watertight state.

Abstract: A water quality meter is composed of a plurality of analyzing units for analyzing water samples introduced from a water distribution pipe, each analyzing unit including a reagent mixing cell and a measuring cell, and a liquid introducing unit integrated with the analyzing units, which is composed of a single member in which a plurality of fluid flows paths for feeding various types of liquid including the water sample into the analyzing unit are formed. Furthermore, the cells and the plurality of three-dimensional fluid flow paths formed in the single member are fabricated by a micro-fabrication technique using photo-curing resin. In one embodiment, a photometer is situated in the flow path in at least one analyzing unit for measuring absorbency of the liquid. In another embodiment, a pair of electrodes, for measuring electric conductivity or pH, is disposed in a measurement flow path in at least one of the analyzing units.

Abstract: An acid concentration continuous measuring apparatus is equipped with the combination of a body having a flow path through which pickling solution contained in a pickling tank is made to continuously pass in a single direction, a density sensor, a temperature sensor, and a conductivity sensor which are installed on the body and substantially continuously measure the pickling solution flowing along the flow path, and a calculating apparatus which calculates the acid concentration of the pickling solution based on the measured results. Feedback control of the hydrochloric acid concentration in a final pickling tank of a plurality of pickling tanks forming a continuous pickling line is performed using the acid concentration continuous measuring apparatus.

Abstract: Impedance between potential sensing electrodes of a high impedance meter is measured by applying a ramp waveform through a capacitor coupled to one of the electrodes to generate a substantially constant current, a measure of impedance being obtained by comparing this to the potential developed across the electrodes when a different current is flowing.

Abstract: The conduit tube 3 and the conduit tube 4 to flow the carrier solution to the gas exchanger 7 are provided, and in the conduit tube 3, the reference pH electrode 14 is provided, and in the conduit tube 4, the measuring pH electrode 16 is provided, both pH electrodes preferably being chosen of the ISFET type (Ion-Sensitive Field-Effect-Transistor). The gas exchanger 7 is partitioned from the outside by the gas permeable membrane 6. Initially, the gas exchange section 1 is inserted into the test substance, and next, the carrier solution is flowed at the speed of a degree in which the gas exchange is not conducted in the gas exchanger 7. The output potential difference &Dgr;V(0) between the reference pH electrode 14 and the measuring pH electrode 16 at this time, is found.

Abstract: Apparatus for, and a method of, simultaneously measuring the concentration of a selected ion species in a solution and the pH of the solution, uses an ion selective electrode, a reference electrode and an ISFET immersed in the solution. The ion concentration is determined in a first circuit from the potential difference between the ion selective electrode and the reference electrode, and the pH is determined in a second circuit from the current flowing between the ISFET and the reference electrode. The reference electrode is connected into the second circuit via a high resistance so as to isolate the two circuits from each other. The earth potential of the solution is connected to provide the earth potential of the first circuit, and is connected to the second circuit via a high capacitance so as to provide a virtual earth thereforee. Each circuit is supplied from a separate power source, and the circuit outputs are supplied via respective isolation amplifiers to a multi-channel meter.