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: A pinch valve for selectively pinching or releasing a multiple plurality of fluid conduits includes a rotatable single cam as part of a rotor within a stator for locating the fluid conduits. The cam periphery with different lobe surfaces for engaging movable means which is either a plunger or a endless belt which pinch or release multiple fluid conduits. The rotor integrally includes a gear, shaft and flag indicator and is operable by a stepper motor. A backing means about the stator resiliently resists movement.

Abstract: A sample handling system including a sample injection cell having an open chamber in turn comprising an upper portion for washing a sample handling probe and a lower portion adapted to reeive the probe for injection of a sample and fluid mixture into a flow analysis device. The cell enables the probe to be withdrawn from the cell and moved to other analysis modules for injection of sample therein. The cell includes a seal between the upper portion and lower portion of the chamber and the probe includes a mating seal near the tip of the probe. A plurality of conduits are formed into the cell for flowing sample and a fluid such as diluent through the cell to a flow analysis device and for filling the cell for washing the probe tip.

Abstract: A method for measuring the concentration of a gas. The method includes circulating an electrolyte solution between an electrode and a gas-permeable, ion-impermeable membrane spaced from said electrode. The ionic concentration is measured after the circulating electrolyte has been stopped.

Abstract: A liquid transfer valve including a movable valve portion. A second valve portion is movable with respect to a first valve portion to allow probes to extend therethrough to pick up a liquids. Upon probe retraction, the second valve portion is movable to a position which allows the liquids to be injected into the valve where they are diluted, mixed, and carried to a remote detector or delivery point.

Abstract: A liquid transfer valve including movable valve portions. A second valve portion is movable with respect to a first valve portion to allow a probe to extend therethrough to pick up a sample liquid. Upon probe retraction, the second valve portion is movable to a position which allows the sample liquid to be injected into the valve where it is diluted and carried to a remote detector or delivery point.

Abstract: Apparatus for conveying a blood sample through a flow cell which measures characteristics such as pH, PCO.sub.2, and PO.sub.2 of the sample and for pumping a wash solution through the cell between samples. The flow cell inlet is selectively connected (1) to a sample-filled syringe for driving sample through the flow cell or (2) to a reservoir of the wash solution. The flow cell outlet is connected by a conduit to a waste receptacle. A rotor of a combined peristaltic pump and valve coacts with an elastomeric tubular section of the conduit. The rotor and the elastomeric section are movable in a transverse direction relative to each other between (1) a first or pumping position wherein the rotor compressively engages the section for pumping fluid wash solution through the cell and the conduit and (2) a second or relaxed position wherein the rotor is released from the section to provide an open unrestricted channel for the flow of sample driven by the syringe through the cell.

Abstract: Apparatus for automatically and selectively supplying a blood sample or a wash/calibration solution to the entrance port of a flow cell which measures characteristics of the sample such as pH, pCO.sub.2 and pO.sub.2. A sample filled syringe and a solution supply conduit are supported by respective first and second fluid delivery mechanisms which rotate to move the syringe outlet and the conduit outlet in generally arcuate paths toward and away from the flow cell entrance port. The delivery mechanisms are rotated simultaneously, one toward and one away from the entrance port, by a common drive gear. Seating of the wash solution outlet in the entrance port is upstream of the seating of the sample outlet to ensure complete flushing of sample from the entrance port by the wash solution.

Abstract: A method of checking the electrical isolation provided by a gas permeable membrane for a carbon dioxide sensor in an analyzer for simultaneously measuring the carbon dioxide and chloride content of a blood sample as it reacts with a reagent in a sample cell. The method involves actuating the carbon dioxide sensor during its normal "off-time" and measuring any signal generated thereby while a coulometric generator in the analyzer is initially activated to titrate to a repeatable initial value any chloride present in the reagent alone. Any signal generated by the sensor above a predetermined value is indicative of a defective membrane and may be utilized to inhibit further operation of the analyzer.

Abstract: Apparatus for measuring CO.sub.2 in serum with a single pH sensor of the electrolyte flow-through type, the sensor including a gas-permeable membrane selectively passing CO.sub.2 into an electrolyte filled space adjacent a pH sensing electrode for reacting with the electrolyte to produce a pH change therein. The electrolyte space is connected by a conduit to an electrolyte reservoir for flowing fresh electrolyte to and through the electrolyte space prior to a sample measurement. A stainless steel metal electrode directly contacts the electrolyte of constant composition in the conduit upstream of the pH sensor to derive a reference potential thereat. The potential across the pH sensor and the stainless steel electrode is monitored, differentiated, and the maximum value of the differentiated signal measured to determine the CO.sub.2 concentration.

Abstract: Titration apparatus for measuring chloride electrolyte in blood samples including a pair of coulometric generator electrodes for titrating the chloride with silver ions to precipitate silver chloride and a pair of amperometric detector electrodes for detecting completion of the silver chloride precipitation. The amperometric electrodes and one of the coulometric electrodes (cathode) are contained in a unitary electrode module which is mounted separately from the remaining coulometric electrode (anode) and which is readily removable for cleaning.

Abstract: Apparatus for measuring carbon dioxide and chloride in blood. A blood sample is reacted with acid in a sample container to release carbon dioxide, a portion of which diffuses through a gas-permeable membrane and reacts with an electrolyte to change the pH thereof. A pair of pH measuring electrodes monitor the electrolyte pH at respective locations adjacent to and remote from the region of reaction within the electrolyte. The pH electrodes are coupled to respective input terminals of a differential amplifier to derive a differential pH signal. The differential pH signal is differentiated to derive a rate of change of pH output signal which is measured to indicate the concentration of carbon dioxide. The pH measuring electrodes are in electrolytic communication and means is provided to renew the electrolyte between measurements. Coulometric measurement of chloride in the sample is performed simultaneously with the carbon dioxide measurement.

Abstract: An apparatus for automatically performing blood chemistry analyses and in particular the determination of the pH, PCO.sub.2 and PO.sub.2 of blood. The apparatus employs a flow cell having pH, PCO.sub.2 and PO.sub.2 measuring electrodes mounted therein adjacent to a sample passage extending through the cell. Sample is collected in a conventional syringe. The needle of the syringe is removed and the syringe cylinder is attached to the flow cell adjacent to the inlet end of the sample passage. Means are provided for automatically driving the plunger of the syringe into the cylinder to convey the sample through the sample passage. A wash solution is then conveyed through the passage to discharge the sample therefrom and thereafter a calibration solution is conveyed through the passage which permits simultaneous calibration of the pH, PCO.sub.2 and PO.sub.2 electrodes.