Abstract: In particle counting apparatus such as a hematology parameter measurement apparatus for performing multiple measurements on one blood sample, first and second impedance transducers, each including inner and outer electrodes, are provided for selective hydraulic connection to a probe head including one set of pressure ports and a further inner electrode. The first and second transducers are respectively immersed in first and second dilutions of the sample. Measurements on each dilution are made in a conventional manner. The inner electrodes are connected in parallel as are the outer electrodes so that small liquid passageways may be provided between the transducers and the probe head while maintaining a low impedance in the liquid path. Means are provided for selecting the sequence of operations and are provided to increase the throughput of samples for which multiple measurements are made.

Abstract: In a hematology measurement apparatus, a hematocrit value is generated by incrementing a value in accumulation means in accordance with measured sizes of red blood cells. The hematocrit value is corrected for coincidence by incrementing the value additionally in response to the production of red blood cell count coincidence corrections pulses.

Abstract: In an automatic chemical testing apparatus in which radiant energy readings are taken from a liquid sample of reacted contents comprising reagent and one or more aliquots, one per channel, of a sample fluid, a statistically large number of readings are taken on each sample. For example, in a readout cycle, 32 readings are taken on each channel for a sample. For an end point chemistry, calculation of an output value is based on the mean of a plurality of readings which are a subset of all readings. For a kinetic chemistry, the output reading is based on a slope of a curve defined by subsets of successive readings.

Abstract: In a spectrophotometric measuring apparatus sample liquid is pumped into a substantially cylindrical cuvette having an internal dimension such that a meniscus of a leading edge of a liquid sample pumped therethrough is maintained. Radiant energy directed through the sample liquid is directed across the path of fluid flow rather than along the length thereof. Consequently, spectrophotometric measurement is performed using a significantly reduced optical pathlength.

Abstract: An improved reagent system for chemical determinations and novel compositions therefor provide improved reagent stability, particularly in a dry, storage stable phase. For determinations in which hexokinase and glucose-6-phosphate dehydrogenase are indicator enzymes, glycine and taurine are combined with bovine serum albumin to provide a bulking agent for the indicator enzymes which also acts as a stabilizer. A novel salt, the tris (hydroxymethyl)aminomethane salt of 2 mercaptosuccinic acid, acts as an activator or stabilizer in chemistries utilizing the indicator enzymes, namely determinations of creatine phosphokinase or glucose. The novel salt also acts as a stabilizer in a urea nitrogen determination. Dry reagent components are bulked in triethanolammonium terepthalate. Novel CPK, glucose and serum urea nitogen determinations are also provided.

Abstract: An improved reagent system for chemical determinations and novel compositions therefor provide improved reagent stability, particularly in a dry, storage stable phase. For determinations in which hexokinase and glucose-6-phosphate dehydrogenase are indicator enzymes, glycine and taurine are combined with bovine serum albumin to provide a bulking agent for the indicator enzymes which also acts as a stabilizer. A novel salt, the tris (hydroxymethyl)aminomethane salt of 2 mercaptosuccinic acid, acts as an activator or stabilizer in chemistries utilizing the indicator enzymes, namely determinations of creatine phosphokinase or glucose. The novel salt also acts as a stabilizer in a urea nitrogen determination. Dry reagent components are bulked in triethanolammonium terephthalate. Novel CPK, glucose and serum urea nitrogen determinations are also provided.

Abstract: In a hematology parameter measuring apparatus, signals indicative of measured parameters are obtained and loaded into first digital registers. Calculated parameter values are generated through use of the values stored in the digital registers. A first parameter value is circulated from a register into a digital divider through a digital data line to set a divisor in the divider. A control circuit circulates a value from another register to the divider for utilization as a signal indicative of a dividend. The output of the divider is coupled to a result register to store a value indicative of the calculated parameter. In this manner, calculated parameter values are obtained, and the first registers retain values indicative of the measured parameter values. The control means may selectively couple signals to a display from any of the registers or to a printing unit.

Abstract: In an automatic chemical testing apparatus in which different chemical tests are performed selectively on one or more aliquots of each of a number of samples, samples are placed in successive ordinal positions for sequential aspiration into the apparatus for testing. Selection means in a selection panel are actuated to enable a position, i.e. to enable storage of instructions for tests to be performed on a sample in a particular ordinal position after it is aspirated into the apparatus. Test selection means are operated to program tests to be performed for the sample in the enabled position. Indicator means, e.g. lamps, are energized to indicate which position is enabled and which positions have been programmed. A further display indicates which tests have been programmed for an enabled channel.

Abstract: Means for reducing intersample contamination in an automatic chemical testing apparatus, in which liquid from a sample is aspirated from a sample source into a reservoir, and aliquots of the sample are each dispensed into individual reaction containers for analysis by well-known means. A cylindrical reservoir is utilized with a piston therein shaped for pushing out virtually all of the remaining sample from the cylinder after dispensing the sample liquid through a hollow needle, communicating with the cylinder. A solid pin coaxially mounted within the piston is projected through the needle and has minimum clearance therewith, for pushing remaining sample out of the needle. The portion of the pin projecting through the needle is retracted into the piston prior to aspiration of liquid from a next sample.

Abstract: A system for simultaneously monitoring one or a plurality of patients samples each electrocardiac waveform of each patient to generate a model waveform for each patient. The image is resolved into contour intervals, e.g. PR, QR, ST and T intervals, and the system establishes a set of interval limits for each patient to which samples of subsequently monitored waveforms are compared. Errors associated with each patient are separately stored and reported by the system in an order which may correspond to a priority ranking of the seriousness of the conditions with which the errors are associated.

Abstract: A fail safe detector in a cardiac monitoring system provides an alarm to indicate failure of the system to respond to cardiac waveforms supplied thereto from cardiac waveform sources. A time out circuit will produce the alarm if not periodically reset by pulses produced in response to measurement of cardiac waveforms. Means are provided for sensing whether cardiac waveforms are received from the sources to provide an alternate means of triggering periodic reset signals when no waveforms are received from the sources to prevent false alarms.

Abstract: In a hematology analyzer, peaks of pulses indicative of red blood cells in a sample during a count are detected. Peak detecting means produce a gate signal connected to gate means which couple a portion of each pulse in the time vicinity of its peak to integration means. The level accumulated in the integration means is indicative of total cell volume, and hence indicative of hematocrit for a known sample volume.

Abstract: In an automatic chemical testing apparatus, means are provided for dispensing aliquots of a sample to reaction containers. A carriage means housing a self-priming hydraulic circuit mounted for motion on a support arm housing drive means. During an operating cycle, control means operate the drive means to position a conduit communicating with the hydraulic circuit over a sample source and aspirate an amount of the serum into the hydraulic circuit. The carriage means is then moved, preferably at uniform rate over a row and dispensing means are pulsed to dispense samples into individual reaction containers while the carriage means is moving. The carriage means is then returned to its starting position.

Abstract: In an automatic chemical analyzer, a reagent dispensing system is provided for delivering reagent from containers in a reagent compartment to reaction stations. A mounting block assembly is formed with a first bore therethrough for providing a reagent flow path whose direction of flow is regulated with check valves. A second bore normal to the first bore and communicating therewith is provided for receiving a piston having travel-limiting radial flange means formed at the end thereof remote from the first bore. A solenoid is mounted to the block having a plunger for activating the piston.

Abstract: An apparatus and method are provided for measuring hematocrit. A diluted blood sample is passed through a well-known conductivity sensor providing a sensor pulse for each sensed blood cell. Each pulse has a peak amplitude corresponding to the size of a blood cell passing through the sensor. During a first time period initiated by passing of the sensor pulse above a threshold level, the sensor pulse is coupled to peak detecting means, and a signal indicative of the level of the peak is generated and stored. The value of each stored signal is added to an integrator for a fixed period of time. The value stored by the integrator is thus indicative of hematocrit level for a known sample volume.

Abstract: In a flame photometer in a chemical analyzer, an electrical spark is used to ignite gas. An improved construction is provided in which an electrode is provided at the center of a nozzle screen, and the nozzle screen is utilized as a ground terminal. An improved electrode assembly facilitating ease of connection of a power source to the electrode is also provided.

Abstract: Apparatus and method are provided for determining mean corpuscular volume of cells in a sample passing through a conductivity cell. A coincidence corrected red blood cell count is generated by conventional means, and a signal indicative of hematocrit level is provided. A digital representation of the corrected red blood cell count is loaded into a register connected to comparator means. A digital output generated in response to the hematocrit level indicated by the hematocrit signal is utilized as a clock pulse train. The clock pulse train has a total length indicative of the hematocrit level, or a multiple thereof. The count indicated by the clock pulse train is compared by the comparator means, which acts as a divider, to the red blood cell count. The output of the comparator means comprises a digital number which is indicative of the mean corpuscular volume of a sample.

Abstract: In a blood analyzer, improved calibration is provided. First and second photodetectors sense energy supplied directly from a source and from the source through a sample respectively. A log ratio amplifier provides an analog output indicative to the log of the ratio of the outputs of the photodetectors to a control circuit. When a blank sample is measured, a programmable voltage source operates to set the analog output to a selected level. A reference sample having optical density corresponding to a preset value is next measured, and a variable gain amplifier is set by the control circuit to cause the analog signal to correspond to the preset value.

Abstract: A hematology analyzer provides a pulse signal in which the number of pulses manifests the number of blood cells in a sample volume of blood and the magnitude of each pulse manifests the size of each such blood cell. The analyzer also provides an analog voltage manifesting the hemoglobin content of the blood sample. Means responsive to the pulse signal provide an analog voltage manifesting the hematocrit of the blood sample and an analog voltage manifesting the number of cells. An analog-to-digital converter is switchably responsive to the analog hemoglobin, hematocrit and cell count signals to provide required ratios reflecting the mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration of the blood sample.