Sherwood Medical Industries Inc.

Vincent H Li

Ronald Crouther

Larry H Dodge

Holvor W Ashley

A method and apparatus for the detection of the magnitude of selected chemical substances in a biological fluid by fixed rate analysis. Photometric analysis is performed sequentially upon a standard solution and then upon an unknown sample to determine the rate reaction in each. The method and apparatus minimize or eliminate error in equipment drift and calibration. The rate reaction is manually initiated in a standard solution carrying a known amount of a chemical substance. The standard is then placed into a photodetector circuit to produce a voltage representing optical density which increases at a constant but unknown rate during the reaction. The time required for the voltage to change from a base-line level to a selected and pre-set value is then measured and stored as a calibration reference time. Then, the rate reaction in the sample carrying an unknown amount of the chemical substance is initiated and the standard is replaced by the sample in the same photodetector circuit to produce a voltage representing optical density of the unknown sample. The voltage representing the optical density of the unknown sample increases at a constant but unknown rate and the rate is proportional to the amount of chemical substance in the sample. The voltage level at the end of the calibration reference time represents the change in the optical density of the unknown sample which, in turn, indicates the amount of chemical substance in the sample with respect to the standard sample. The voltage level is then provided to a display which indicates the amount of the chemical substance in the sample.

Rate measurement analyzer

A blood collection device used in taking a small sample from a patient for test purposes is provided with a capillary tube and vented tube holder disposed in the upper end of a blood collection container. Integral radial extensions allow the container to be centrifuged in a centrifuge normally used for containers of larger diameter. An integral flexible strap connects a stopper to one of the radial extensions so that the stopper remains with the container.

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Maryland Heights, MO, United States of America

Vincent H Li