Comparisons of integration vs. rate measurements for oxidase enzymatic analyses

Results obtained by integration of net indicator-substance signals during the progress of a reaction are compared to those concurrently achieved by rate estimation with the time vs. signal data, for glucose oxidase assays and enzymatic glucose determinations. Computer-simulated integration results typically exhibit data quality superior to that of rate measurements, for the entire very wide ranges of oxidase activities and concentrations studied. Only at extreme instrument-noise levels and low analyte values did any of the rate procedures (the variable-time method) show some advantage over integration. The data quality, expressed as relative uncertainties, of the simulated results obtained by use of the integration method was typically up to 120 times better than that obtained by rate methods, with greater enhancement at higher enzyme activities or substrate concentrations. Experimental results spanning physiological concentrations showed similar trends, but the advantage was not as great as that shown in the simulations.