ATP is determined by measuring the competition for glucose between a hexokinase-catalyzed dephospnorylation of ATP and glucose oxidase catalyzed oxidation of glucose. The ATP competition for glucose decreases the rate of oxygen consumption via the oxidation reaction, which is measured amperometrically with a Clark oxygen electrode. The decrease in the oxygen depletion is proportional to the concentration of ATP in the sample. A 10 to 50 μl sample is required and analyses are completed in 3 minutes or less.

A kinetic, two-point method for the assay of α-arnylase in serum, involving spectrohotometric measurement of a starch-iodine complex, is described. This approach avoids interferences by serum proteins and other substances that react with iodine. The method requires less than 4 min per assay, only 10 μl of sample is used, and precision and accuracy are comparable to those of established procedures.

An enzymatic method for the rapid, direct kinetic measurement of maltose is described. Maltose is hydrolysed to glucose by α-glucosidase, and the glucose reacts with oxygen in the presence of glucose oxidase to form gluconic acid and hydrogen peroxide. The rate of oxygen depletion is measured with a Clark oxygen electrode. The glucose oxidase reagent contains sufficient amounts of α-glucosidase impurity for a maximum reaction rate to be obtained within 2 min after addition of maltose to the reagent. The reaction rate is obtained directly by recording the derivative of the change in amperometric current. Glucose already present in samples can be destroyed by incubation with purified glucose oxidase reagent for 10 min. Fructose, lactose and galactose do not interfere. Interference from starch (constant over a wide range of starch concentrations) can be readily corrected for by adding starch to standards, and sucrose interference can be minimised by adjustment of the pH. Excellent results were obtained for the recovery of maltose from pooled serum samples.