Abstract: An electrochemical detection cell which includes, in the order named, a stack of components constituted by a first membrane, an electrode carrier having reference and counter electrodes thereon, a membrane support, an electrode carrier having a sensing electrode thereon, and a permselective membrane. Whatman filter papers are positioned between the sensing electrode and both the counter electrode and reference electrode, these being positionable in a central rectangular opening of the membrane support. The cell allows air or gas ambient to address the membranes and effects application of an electrolyte to space between the electrodes by, for example, a wick which extends between an electrolyte-containing reservoir and the Whatman filter papers. A system for detecting a gaseous agent uses the aforementioned detection cell coupled with circuitry capable of applying a fixed DC voltage bias to the reference electrode and superimposing a train of DC voltage pulses on the fixed bias.

Abstract: A method of analyzing a sample material by liquid chromatography is described wherein the sample is dissolved in a carrier fluid to form a mobile phase. The mobile phase is electrochemically treated to selectively remove electroactive materials therein or to change chromatographic characteristics of said materials therein prior to passing the mobile phase to a chromatography column.

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

Abstract: An electrochemical cell is provided with plural identical selective electrodes and at least one chemical reactor for the indirect measurement of clinical-chemical parameters. The electrodes are ion-selective for the same ionic species or gas-selective for the same gaseous species. One of the two electrodes can be used as a measuring electrode and the other as a reference electrode. In the case of gas-selective electrodes, the reference electrode can be selective for a different ionic species. A third electrode with just electrical conducting properties can be provided. The chemical reactor can utilize immobilized enzymes, or immobilized substrates, or ion exchange resins, and is preferably connected to the measuring electrode only. Two fluidic paths may be provided in the electrochemical cell, as well as one input and two outputs, or two inputs and just one output in sequence.

Abstract: An electrochemical detector cell (10) and apparatus incorporating the cell (10) includes a first capillary (12) having an entrance (14) connected to an electrolyte source (30) and an exit (16). A second capillary (18) is connected to reactive gas source (32) and intersects the first capillary (12) at (22) to define a reaction zone (20) in the first capillary (12). A sensor electrode (24) is positioned in the first capillary (12) in the reaction zone (20). A third capillary (26) intersects the first capillary (12) within the reaction zone (20). A reference electrode (28) is positioned in the third capillary (26). The third capillary (26) is connected to a solution source (34). The electrodes (24) and (28) may be used for potentiometric measurements. A fourth capillary (38) intersects the first capillary between entrance (14) and intersection (22) of the first capillary (12) and the second capillary (18).

Abstract: The present invention relates to electro-analytical measuring equipment for the determination--by means of one or more measuring cells comprising sensing elements of chemical similar composition, being in constant galvanic contact with each other--of the concentration and ion-activity of solutions or of the partial pressure of gases. The sensing elements are in contact with sample or with one or more standardizing media separated in time or space. At least two reference electrodes are in direct or in indirect contact--through electrolite--with sample and standardizing medium. The reference electrodes join, in a given case, to electronic signal processor comprising arithmetic unit calculating, by fault compensation, value of one or more parameters to be measured.

Abstract: An amperometric cell modified for high pressure operation is described. The cell is a flow-through type cell defining a flow path and has at least one active testing electrode, at least one reference electrode and at least one counter electrode operatively disposed and electrically insulated from one another within the cell flow path. In a preferred embodiment the flow cell is encapsulated within a high impact, chemically resistant, chemically insulating material, and has a pair of high pressure resistance fittings communicating with the flow path and extending in part beyond the encapsulation. The cell has particular utility for use with a liquid chromatography separation and when placed in line upstream of sample injection, will remove selected electroactive components in the carrier fluid and thereby reduce background level of contaminents reaching the column and eluting from the column.

Abstract: An ion activity or concentration analyzer including an ion selective electrode, a reference electrode and a flow-through electrolytic cell. A sample liquid enclosure conducts a flow of an aqueous sample past the anode and cathode electrodes of an electrolytic cell that is polarized to generate hydrogen and hydroxyl ions. The ion selective and reference electrodes are so positioned, with respect to the cathode electrode, that the hydroxyl ion concentration is increased in the vicinity thereof. This increased hydroxyl ion concentration causes a reduction in the hydrogen ion concentration and thereby substantially eliminates the interfering effect of hydrogen ions on the operation of the ion selective and reference electrodes.

Abstract: An apparatus and method for measuring the concentration of various components in a fluid sample. The apparatus comprises a chemically sensitive field effect transistor (CHEMFET) having a semiconductor substrate and a pair of diffusion regions formed at the surface of the substrate. An electrical insulating layer is positioned adjacent the substrate and a fluid pervious bridge member is mounted to the insulating layer so as to form a gap between the bridge member and insulating layer. The apparatus also includes means for imposing an electrical charge on the bridge member, means for imposing an electrical potential between the diffusion regions, and means for detecting current flow between the diffusion regions. The fluid sample to be analyzed is introduced through the fluid pervious bridge member and into the gap where various components of the fluid sample are adsorbed by the bridge member, and in another embodiment, also by an adsorptive layer which is applied within the gap.

Abstract: A method and apparatus are disclosed for determining sulfur dioxide content in a gas sample. The apparatus is a polarographic- type one having first and second tubular chambers. The first chamber has a gas inlet. Gas coming therein causes an electrolyte to circulate around the two chambers with the second chamber having a sensing electrode and a counter electrode therein.

Abstract: An electrochemical detection apparatus is provided. The apparatus comprises a flow-cell having at least one active testing electrode, at least one reference electrode, and at least one counter electrode. Each electrode comprises a liquid impervious solid body having a bore extending therethrough with the electrode active surface located in the bore. The electrodes are arranged in a stack, electrically insulated from one another with their respective bores aligned so as to define a flow channel through which liquid to be detected can be passed. In a preferred embodiment of the invention at least one of the reference electrodes is actively driven to supply a stable reference potential against which other electrochemical responses can be measured. Various electrochemical responses are achieved by varying the construction, number and arrangement of electrodes in the stack, and the potentials applied to the electrodes. The detection apparatus has particular utility for use in monitoring chromatographic eluant.

Abstract: Determining the oxygen content in gases, particularly combustion exhaust gases, uninfluenced by temperature variations of the gases by passing the gases into a first electrical measuring cell having a solid electrolyte and electrodes connected to a current source. A diffusion-limited electric current flow dependent on the oxygen content of the gases is obtained and measured as a first electrical signal. Passing an auxiliary gas with constant oxygen content into a second measuring cell similar to the first cell and under the same conditions and obtaining a second electrical signal. The quotient of the two electrical signals is a measure of the oxygen content of the gases uninfluenced by temperature variations of the gases.

Abstract: Methods and apparatus are provided for sensing gases in the environment wherein electrochemical sensing procedures are utilized not only for monitoring ambient continuously for the presence of such gases; but also, for the periodic automatic recalibration and self-adjustment of the sensing instrument, as required, to accommodate changing conditions with time. Such accommodation includes not only changes in the instrument itself, but also changes in the environment affecting the accuracy of the monitoring function. The instrument is connected with a microprocessor, or other information storage or retrieval instrumentation which controls the periodic recalibration by measuring, separately from the monitoring function, the electrochemical response to a sample of the gas being monitored, and by adjusting the subsequent instrument readings to reflect the recalibration. During this recalibration procedure, the instrument can be adjusted to zero reading for accommodating drift, as will be understood.