Amperometric assay of glucose and lactic acid by flow injection analysis

A computer-controlled flow-injection system is described for the assay of D-glucose and L-lactic acid in undiluted plasma. Glucose or lactate is quantified by coupling an immobilized glucose oxidase or lactate oxidase membrane with an amperometric sensor; the hydrogen peroxide generated is directly related to the concentration of glucose or lactate. The linear range is 0–40 mM and 0–10 mM for glucose and lactic acid, respectively. The sample frequency is 60 h^?1 with a standard deviation of less than 1.5%. Correlation with the results for blood plasma obtained by routine clinical analyzers was good for both glucose and lactic acid.