Continuous-Flow Analysis for Glucose in Serum, with Use of Hexokinase and Glucose-6-Phosphate Dehydrogenase Co-Immobilized in Tubular Form

co-immobilized at the inner wall of plastic tubing, were used with continuous-flow analyzers to measure serum glucose. The performance of the enzyme-Containing coils meets thehydraulicrequirements of the continuous-flow instruments, and the average carryover does not exceed 2.2%. A glucose concentration change of 1 g/L yields a 0.08 change in absorbance. There is no significant de-viation from linearity for glucose concentrations up to 5 gIL. The method is similar to the Reference Method pro-posed by the Food and Drug Administration, and results by the two methods agree and correlate well (r = 0.999). The operational stability of the enzyme tubes is sufficient to allow the analysis of at least 10 000 serum samples. We investigated in detail the effect of reagent concentrations and temperature on the performance of the enzyme coils