SIMULTANEOUS ASSAYS OF GLUCOSE, URATE, AND CHOLESTEROL IN BLOOD-SERUM BY AMPEROMETRIC FLOW-INJECTION ANALYSIS

Glucose, uric acid, and cholesterol in serum were assayed simultaneously in a how injection system by using a 16-way switching valve and a parallel configuration of three immobilized enzyme reactors. Nafion film-coated and Nafion/cellulose acetate him-coated platinum electrodes were used to selectively detect the hydrogen peroxide generated enzymatically in the enzyme reactors, without any interferences from electroactive species such as L-ascorbate and proteins present in the serum. The signal current was linearly related to the glucose concentration in the range of 5-700 mg/dL, to the urate concentration in the range of 1-80 mg/dL, and to the cholesterol concentration in the range of 5-100 mg/dL. The precision (coefficient of variation) was better than 2.8% for the simultaneous assay of the three species in human control serum. The assay speed was up to 32 samples per hour.