A measuring instrument and system for the determination of the partial oxygen and carbon dioxide pressures and of the pH value of a blood test sample having a thermostatized measuring vessel with a measuring capillary tube inserted therein to contain the blood test sample with three receiving bores in the measuring vessel and three measuring electrode units one of which being oxygen sensitive with the second carbon dioxide sensitive and the third being pH sensitive. Each of the measuring sensors are in contact with the said blood test sample and a measuring and recording device for electrode conductively connected with one of the measuring electrode units with a conical receiving bore provided on the measuring vessel. Three control bores terminate in the conical receiving bore and a switch element is inserted in the receiving bore to register with the control bores in three different positions with a pumping device providing for alternate suction and delivery strokes and a pipeline connects the pumping device with the control bores. A gas intake pipe connects the pressure tank with the second control bore and a suction pump and a suction pipe connect the latter with the third control bore and a conical filler connection is mounted on the measuring vessel and is connected with the extremity of the measuring capillary tube opposite the switch member.
A system for determining values of pH, PCO.sub.2, PO.sub.2, HCO.sub.3, total CO.sub.2 and base excess in a small sample of blood. The system comprises a measuring chamber common to the sensing portions of a flow-through pH electrode, a pH reference electrode, a carbon dioxide (PCO.sub.2) electrode, and an oxygen (PO.sub.2) electrode. In line and communicating with the chamber exit is a peristaltically activated pump which can draw small samples of blood into the chamber followed by a vacuum system for drawing the sample out of the chamber. Communicating with the chamber entrance is a flush system for cleansing the chamber after the blood has been analyzed. The system also includes circuitry associated with the output of the electrodes for quickly determining and digitally displaying values for pH, PCO.sub.2, and PO.sub.2, and analogue calculators adapted to receive and apply values from the pH and PCO.sub.2 electrodes to determine and digitally display values for HCO.sub.3.sup.- , total CO.sub.2, and base excess.
An apparatus for measuring at least two of the following characteristics of a fluid; pH, partial pressure of dissolved gas or gases therein, inorganic ion concentration, hemoglobin, temperature, and the like, the apparatus comprising a vessel having a flow channel for fluid passing therethrough and means for inducing turbulence in the channel at specified locations; sensors for the above enumerated fluid characteristics located in the vessel along the channel and within the area of induced turbulent flow; and integral heat-exchanging means e.g., cartridge heaters, within the vessel and external solid state circuitry for maintaining or achieving a preselected temperature in a fluid passing through the vessel and in the sensors. Also disclosed is such an apparatus adapted to the analysis of very small quantities of fluids, e.g., blood, including components for sample storage and transfer, preheating, propulsion and electronic read out and display.
A sensor and method are disclosed for measuring electrokinetic effects across a double layer formed at the boundary between a solid wall and an ionic liquid flowing through a channel. In one embodiment, a passive electrode is located in a cavity forming a tee section with the channel through an orifice of approximately the same size as the channel. A passive second electrode in electrical communication with one side of the double layer is placed on the other side of a porous plug which is located in a second cavity directly opposite the orifice and which is flush with the channel walls. The double layer being investigated is formed on the flush portion of the porous plug. Thus both electrodes are out of the flowing liquid. An electrokinetic potential, labeled the K-effect potential, was measured by the two electrodes. In one use of the sensor, monitoring this potential, the chemical composition of the liquid can be maintained so as to keep a desired surface charge on suspended minerals which are being processed.
The determination of the concentration of compounds such as CO.sub.2 having an influence on the pH of a medium during polarography is described. Characteristics of polarograms when obtained in unbuffered electrolytes (the polarogram plateau slope position of the upper knee and half-wave potential thereof) are pH-sensitive. These can be detected electronically and signals processed to provide a measure of such concentrations. In one preferred embodiment (FIG. 2) a miniature pO.sub.2 polarographic sensor has cathode channels (A) and (B) biased respecitvely at -750 mV and -950 mV. The output of channel (A) provides pO.sub.2 as in normal polarography. The output of (B) is divided (6) and further corrected for pO.sub.2 (8,10) to provide pCO.sub.2. The apparatus is especially useful for simultaneous pO.sub.2, pCO.sub.2 monitoring in physiological fluids without the need for a separate pCO.sub.2 sensor.
Method and apparatus are disclosed for the determination of the dissociation characteristics of oxygen from blood. The functional relationship between increasing liquid phase P.sub.02 and decreasing pH is determined and presented in the form of a continuous curve for values ranging from desaturation to saturation. By analyzing this data through linear regression techniques, the characteristic parameter of the oxygen dissociation curve P.sub.50, may be easily determined.
