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In oxidase enzyme reactions,
the analyzer measures the rate of oxygen uptake and under appropriate
controlled conditions, this is directly proportional to the
concentration of the analyte.
Substrates for dehydrogenase
enzymes are measured using a pre-reaction in which the oxidation
of NADH (produced or consumed) is then monitored.
Under the conditions of the assay, the rate of oxidation of excess NADH by peroxidase (POD) is inversely proportional to ammonia concentration.
Operation: For many assays, the simple injection of a sample is all that is needed to obtain a result and prepare the analyzer for the next analysis. Sample injection via an accurate positive displacement pipette triggers the complete analytical cycle and a hard-copy result is then printed within 20 seconds. The analyzer is first calibrated with a standard of the metabolite in question. Samples can be any aqueous solution (pH 5-7), culture fluid, etc. Turbidity or opacity is no problem. Analyses are menu-driven via the 32-character display which
guides the operator through the complete procedure. Subsidiary
menus are reached via the keypad which enables the user to change
analysis type, optimize operational modes, utilize special functions
and perform statistical data analysis. The display also provides
self-test diagnostics in relation to electrode status and fluid
movements. An RS232 output is available for system integration. |
