Abstract: An ion selective electrode assembly is provided having a sample injection cup, a flow cell analyzer and multiple module pump for simultaneously pumping liquids between the sample injection cup and the flow cell analyzer using a single motor. One of the pump modules is capable of pumping a reference solution directly to the flow cell analyzer. Flow through each pumping module is controlled by a pair of rocker valves. The sample injection cup includes a first diaphragm valve for allowing a mixture of sample and reagent to flow to the flow cell analyzer. The sample injection cup further includes a second diaphragm valve installed immediately downstream of the first diaphragm for allowing a flushing solution to flow throughout the sample injection cup and the flow cell analyzer.

Abstract: A polarographic sensor device to determine the partial pressure of a gas in a sample medium is disclosed. The device comprises a) a substantially hydroscopic electrolyte composition joining a pair of spaced apart electrodes, one of the pair of electrodes being a sensing electrode; b) a membrane permeable to gas but impermeable to the electrolyte, the membrane having a front section for separating the electrodes and the electrolyte from the sample medium; and c) a fastener comprising a sleeve having a body portion and a lip, the body portion retaining the fastener and a side section of the membrane, and the lip retaining a portion of the front section of the membrane and holding substantially the entire front section in a spaced apart relationship from the sensing electrode.

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: An indirect potentiometric method and diluent for the analysis of lithium are disclosed. The diluent includes effective amounts of a pH buffer and a non-cationic surfactant comprising at least one hydrophobic group, at least one hydrophillic group and being substantially free of polyoxyethylene groups. Most preferably, the pH buffer is tris-(hydroxymethyl) aminomethane-phosphate, and the surfactant is 2, 4, 7, 9-tetramethyl-5-decyn-4,7 diol. An indirect potentiometric determination of lithium in a clinical sample comprises the steps of mixing the sample with a diluent, contacting an aliquot of the diluted sample with a lithium specific ion selective electrode and at least one ion selective elctrode specifically responsive to a monovalent interfering ion, and measuring both the response of the lithium specific ion selective electrode and the monovalent interfering ion specific ion selective electrode, the responses being an indication of the concentration of lithium in the sample.

Abstract: An improved solid-state ion-selective electrode has greater uniformity of asymmetric potential and high sensitivity and selectivity for the cation of interest. The electrode comprises: (1) a porous element comprising graphite; (2) an electrochemical reference in substantially dry form on at least a portion of the element, the reference comprising: (a) an oxidant and (b) a reductant that is the conjugate of the oxidant, the oxidant and reductant being present in about equimolar quantities; and (3) a polymeric membrane comprising an ion-selective ionophore in electrochemical contact with the electrochemical reference. The electrode can be prepared to be selective for one of a number of cations, including lithium and ammonium. Methods for preparing these electrodes are also disclosed.

Abstract: An automatic chemistry analyzer includes a flow cell mounted so that flow through the cell and tubing connected to the cell is visible from the front of the housing. The electrolytes to the cell are removably plugged into the cell from their rear. The probe aspirating sample fluid into an injection cell is simultaneously washed by diluent and the diluent mixes with the fluid sample. Waste fluid from the flow cell is fed to a basin which then feeds under gravity to a waste drain. A ratio pump is formed by selected syringes which are band driven to deliver accurately prerequisite volumes of reagents to the flow cell. The solution ground to the system is on the inlet line for sample adjacent the entrance to the flow cell of fluid thereby minimizing electronic noise. Only two motive means are necessary, one to effect horizontal and rotational movement of the sample tray, and a second to effect vertical motion of a crane mounted probe operative between sample cups and an injection cell.

Abstract: An automatic chemistry analyzer includes a flow cell mounted so that flow through the cell and tubing connected to the cell is visible from the front of the housing. The electrolytes to the cell are removably plugged into the cell from their rear. The probe aspirating sample fluid into an injection cell is simultaneously washed by diluent and the diluent mixes with the fluid sample. Waste fluid from the flow cell is fed to a basin which then feeds under gravity to a waste drain. A ratio pump is formed by selected syringes which are band driven to deliver accurately prerequisite volumes of reagents to the flow cell. The solution ground to the system is on the inlet line for sample adjacent the entrance to the flow cell of fluid thereby minimizing electronic noise. Only two motive means are necessary, one to effect horizontal and rotational movement of the sample tray, and a second to effect vertical motion of a crane mounted probe operative between sample cups and an injection cell.

Abstract: An automatic chemistry analyzer includes a flow cell mounted so that flow through the cell and tubing connected to the cell is visible from the front of the housing. The electrolytes to the cell are removably plugged into the cell from their rear. The probe aspirating sample flud into an injection cell is simultaneously washed by diluent and the diluent mixes with the fluid sample. Waste fluid from the flow cell is fed to a basin which then feeds under gravity to a waste drain. A ratio pump is formed by selected syringes which are band driven to deliver accurately prerequisite volumes of reagents to the flow cell. The solution ground to the system is on the inlet line for sample adjacent the entrance to the flow cell of fluid thereby minimizing electronic noise. Only two motive means are necessary, one to effect horizontal and rotational movement of the sample tray, and a second to effect vertical motion of a crane mounted probe operative between sample cups and an injection cell.

Abstract: An indirect potentiometric method and diluent for the analysis of lithium are disclosed. The diluent includes effective amounts of a pH buffer, at least one lithium salt, and a non-cationic surfactant containing at least one hydrophobic group, at least one hydrophillic group and being substantially free of polyoxyethylene groups. Most preferably, the pH buffer is tris-(hydroxymethyl)aminomethane-phosphate, the lithium salt is lithium chloride, and the surfactant is 2,4,7,9-tetramethyl-5-decyn-4,7 diol.

Abstract: A reagent of the type comprising an acid, a molybdate salt, a non-ionic surfactant, and polyvinylpyrrolidone (PVP). The reagent is characterized in that it further comprises an enhancing amount of at least one sugar alcohol. Also, a method for assaying inorganic phosphorus of the type which comprises mixing a sample of biological fluid with a reagent and measuring the absorbance of the resulting solution. The method is characterized in that the above reagent is employed therein. The method can further be characterized in that the measurement can be made via a rate technique.

Abstract: An albumin reagent of the type comprising bromcresol green, a buffering agent having a buffering capacity in the pH range of about 4 to about 4.2, and polyoxyethylene(23) lauryl ether. The albumin reagent is characterized in that it contains from about 0.18 to about 0.22 gm/l bromcresol green and has a polyoxyethylene(23) lauryl ether:bromcresol green weight ratio of from about 10:1 to about 12:1.