Rate measurement analyzer

A system for measuring chemical substances in biological fluids comprising:

• means for providing a source of radiant energy;
• means for detecting radiation from said source and providing a voltage output;
• means for receiving and positioning a sample of fluid, in which a rate-reaction has been initiated, in the energy path between the source and detecting means;
• means operable in a calibrate mode to measure a time period during which the voltage changes by a predetermined amount when a known concentration sample is positioned in the receiving means, and operable in a test mode for measuring the voltage change during a time equal to the previously measured time period when an unknown sample is positioned in the receiving means;
• and
• means for displaying the measured voltage change during the test mode.

A method of determining the amount of a selected chemical substance in a first biological fluid carrying an unknown amount of the selected chemical by comparing a rate reaction of the biological fluid to a rate reaction of a second biological fluid carrying a known amount of the selected chemical substance, comprising:

• subjecting the second fluid to a light source;
• providing a first voltage proportional to light passing through said second fluid as the rate reaction continues;
• measuring the time required for the first voltage to increase from one level to a selected higher level;
• subjecting the first fluid to the light source;
• providing a second voltage proportional to the light passing through said first fluid;
• measuring the second voltage for a period of time equal to the time required for the first voltage to increase from said one level to said selected higher level;
• displaying the measured second voltage at the conclusion of the period of time to provide an indication of the amount of selected chemical substance in said first fluid.

A method of measuring an unknown amount of a selected chemical substance in a biological fluid, comprising:

• selecting a fluid carrying a known amount of the selected chemical substance;
• initiating a rate-reaction in the fluid carrying the known amount of the selected chemical substance;
• exposing the fluid to a light source while the rate-reaction continues;
• measuring the optical density of the fluid carrying the known amount of the selected chemical substance while the rate-reaction continues;
• providing a first voltage proportioned to the optical density of the fluid carrying the known amount of the selected chemical substance as the rate-reaction continues;
• measuring and storing the amount of time required for the voltage to increase from a first level to a second level to provide a calibration reference time;
• initiating a rate-reaction in the fluid carrying the unknown amount of the selected chemical substance;
• exposing the fluid carrying the unknown amount of the selected chemical substance to the light source while the rate-reaction continues;
• measuring the optical density of the fluid carrying the unknown amount of the selected chemical substance while the rate-reaction continues;
• providing a second voltage proportional to the optical density of the fluid carrying the unknown amount of the selected chemical substance as the rate-reaction continues;
• measuring the second voltage for a period of time equal to the calibration reference time;
• and
• measuring the second voltage at the end of the calibration reference time to provide an indication of the amount of selected chemical substance in the biological fluid.