Abstract: A multimode electrochemical sensing array formed on an integrated circuit chip is structured to provide electrochemical determination of acidity or alkalinity, as well as electrochemical and potentiometric measurement of oxidation/reduction potentials, conductivity measurements, electrostatic discharge protection, and ground provisioning.

Abstract: An improved ion-selective electrode with enhanced sensitivity and reliability. The electrode is readily formed from an electrode assembly sealingly joined to the upper end of an electrode chamber whose lower end opens into in a tube bore of substantial path length that provides a conductive path between the electrode assembly and a sensing tip of the electrode. The electrode assembly itself takes the form of a generally helical coil formed on a post extending from the upper end of the assembly and positioning a substantial length of conductive lead remote from the sensing tip of the electrode. The electrode chamber is thermally insulated from the main body of the electrode, and adverse temperature effects are thus greatly minimized. A self-cleaning junction has also been developed. Increased reliability for a given sensitivity have been found to result from the construction.

Abstract: The present invention is directed to a stable, non-hazardous solution for calibrating oxidation-reduction potential (ORP) measurement cells. The redox standard calibration solution of the present invention consists essentially of an aqueous solution containing the triiodide/iodide redox couple. In a preferred embodiment, the solution of the present invention consists essentially of an aqueous solution containing up to about 0.01 moles per liter of iodine (I2) and at least about 1 mole per liter of potassium iodide. In a most preferred embodiment, the solution of the present invention consists of an aqueous solution of 4 molar potassium iodide (KI) and 0.0067 molar iodine (I2).

Abstract: The accuracy and temperature-independence of ion-selective electrode meters having a logarithm resistance temperature correction incorporated therein is enhanced by using a microprocessor controlled and measured circuit with switched reference and switched capacitor filter, and by adding a linear membrane resistance term to the algorithm to improve accuracy across a wide temperature range.

Abstract: The present invention provides an electrophoretic separation system on a planar chip of glass or plastic material with on-chip FIA (flow injection analysis) injection and one or multiple sets of electrodes for on-column, end-column, off-column electrical or electrochemical, suppressed or unsuppressed, conductiometric, high-frequency contactless conductiometric, potentiometric and amperometric detection.

Abstract: A new type of ion-selective solvent polymeric or liquid membrane electrode is constructed which allows to extend the measuring range at the lower end by at least six (6) orders of magnitudes. The new method can be used with membranes based on a neutral ionophore, a charged ionophore, or an ion-exchanger. Low detection limits are achieved by maintaining a very low and constant concentration of the primary ion and a sufficiently high concentration of an interfering ion in the internal reference solution. The low and constant concentration of the primary ion is either adjusted with the help of a solution of a hydrophilic ion buffer such as ethylenediamine tetraacetic acid or by adding an excess of a salt of an ion which forms a sparingly soluble salt with the primary ion, such as NaI for the primary ion Ag.sup.+. With the new technique, ion-selective electrodes can be used, for the first time, for environmental monitoring of heavy metal ions such as Pb.sup.2+ and Cd.sup.2+ at the submicromolar level.

Abstract: Described is a combination, PVC-membrane, Ion-Selective Electrode (ISE) with a replaceable sensing module and a single-junction, sleeve-type reference electrode. pH and ion-selective electrodes (ISEs) in the "Combination" configuration, i.e., single probes containing both the sensing and reference half-cells, are more convenient, more economical, and can be used to analyze smaller samples than an equivalent pair of separate half-cell electrodes.

Abstract: Disclosed is a two-point calibration procedure, that when used with a mathematical algorithm, improves the accuracy of electrolytic conductivity measurements by correcting for non-linear behavior of conductivity cells. Unlike purely mathematical means of correcting for non-linearity which may use second or higher order equations, this algorithm has the following advantages: it is based on an analysis of the physical phenomena which are responsible for non-linearity; it yields one unique solution, i.e., it uses an equation that has only one root; and it yields diagnostic information concerning the behavior of the cell.

Abstract: A new substrate for the construction of solid internal contact ion-selective electrode comprising a conductive and porous carbon matrix is described. The well-defined (i.e., fixed) interfacial potential between the organic electroactive phase and the internal reference element, coupled with the electrode's very slow change from water activity at the internal reference element, supports the well-behaved and reproducible electrode operation. Solid contact sensors for two different ions were constructed, and their potentiometric behavior was compared with their symmetric counterparts. The potentiometric response was monitored over a period of one month with excellent results for drift, base line stability, response time, selectivity, and detection limit.

Abstract: Described is a combination, PVC-membrane, Ion-Selective Electrode (ISE) with a replaceable sensing module and a single-junction, sleeve-type reference electrode. pH and ion-selective electrodes (ISEs) in the "Combination" configuration, i.e., single probes containing both the sensing and reference half-cells, are more convenient, more economical, and can be used to analyze smaller samples than an equivalent pair of separate half-cell electrodes.

Abstract: A connectorized capillary and in-line flow cell system which greatly expedites the construction of capillary zone electrophoresis (CZE) and other separation instrumentation. A capillary is mounted within a cavity formed in a body, and a mechanical fastener is positioned about the body. The inner diameter of the fastener is less than the outer diameter of the body, so that the connector may be firmly coupled to any system component having a corresponding portion adapted to accept the fastener. The connectorized capillaries thus permit permanent or semi-permanent attachment to various in-line flow cell devices such as detectors, valves, buffer reservoirs and the like. For example, an in-line conductivity detector is assembled by connecting a conductivity meter to the opposing ends of the flow cell body. Annular sensing surfaces can also be provided within the cell.

Abstract: The present invention is a reagent which, when added as a conditioning solution to samples containing calcium and magnesium, selectively converts the calcium into a complex which does not interfere with magnesium ISEs, and thus allows accurate magnesium determinations by ISE in a wide variety of samples. The conditioning solution also eliminates strontium and barium interferences by the same mechanism, but these are of secondary importance because they occur in samples less frequently and because they interfere less severely. Also, the formulation of the reagent was optimized solely in order to eliminate calcium interference and its ability to remove strontium and barium interferences was surprisingly fortuitous.

Abstract: A connectorized capillary and in-line flow cell system which greatly expedites the construction of capillary zone electrophoresis (CZE) and other separation instrumentation. A capillary is mounted within a cavity formed in a body, and a mechanical fastener is positioned about the body. The inner diameter of the fastener is less than the outer diameter of the body, so that the connector may be firmly coupled to any system component having a corresponding portion adapted to accept the fastener. The connectorized capillaries thus permit permanent or semi-permanent attachment to various in-line flow cell devices such as detectors, valves, buffer reservoirs and the like. For example, an in-line conductivity detector is assembled by connecting a conductivity meter to the opposing ends of the flow cell body. Annular sensing surfaces can also be provided within the cell.

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: The present invention comprises an electrochemical metering apparatus that provides for convenient storage and presentation of the analytical electrode, simple assembly, and two calibration modes. The apparatus includes an electrode storage and presentation assembly that permits the user to introduce the electrode into a sample solution while simultaneously observing the meter's output, and store the electrode when not in use. All structural components are intended to fit together with interlocking tabs and windows. A serial port fits within the construction of the main housing without the need for bolts, and battery clips that depend directly from the circuit board obviate the need for wiring connections. The present invention also features two calibration modes. A "segment addition" mode permits separation of the voltage/concentration curve into individually plotted regions, the number of which depends on the number of reference solutions used in the calibration procedure.

Abstract: The present invention comprises an electrochemical metering apparatus that provides for convenient storage and presentation of the analytical electrode, simple assembly, and two calibration modes. The apparatus includes an electrode storage and presentation assembly that permits the user to introduce the electrode into a sample solution while simultaneously observing the meter's output, and store the electrode when not in use. All structural components are intended to fit together with interlocking tabs and windows. A serial port fits within the construction of the main housing without the need for bolts, and battery clips that depend directly from the circuit board obviate the need for wiring connections. The present invention also features two calibration modes. A "segment addition" mode permits separation of the voltage/concentration curve into individually plotted regions, the number of which depends on the number of reference solutions used in the calibration procedure.

Abstract: An electrode holder assembly is provided for holding test electrodes in a sample container. The assembly comprises a vertically aligned lead screw mounted to rotate freely, and a nut, inserted over the lead screw, adapted to move freely over the length of the lead screw when subject to a vertical force. A collet that extends upward from the nut body is biased inwardly by a spring so as to secure a friction fit, substantially free of any backlash movement, between the nut and the lead. Attached to the nut is an electrode holder platform having mounting bores adapted for securing test electrodes therethrough. This assembly allows the test electrodes to be moved up or down, for insertion and removal from a test solution, by one-handed vertical activation of the electrode holder platform. The lead screw, nut, and associated components may all be housed in a tower assembly so that only the electrode platform is exposed.

Abstract: The body of an ion-sensitive electrode is formed from a bulb (32) of an ion-selective material that is transparent to infrared radiation. A glass tube (12) made of material that absorbs infrared radiation is inserted into the bulb, and a source (15) of infrared radiation is focused through the bulb (32) onto the end of the tube (12) on which the bulb (32) rests. The resultant heating causes the tube and the bulb to fuse together, and the portion of the bulb outside the tube is then removed to result in an electrode body (FIG. 4).