Rapid polarographic microdetermination of dissolved oxygen in water with flavin enzyme

Abstract

The rapid polarographic microdetermination of dissolved oxygen in water with flavin enzyme, β-D-glucose oxidase [EC 1.1.3.4; β-D-glucose: oxygen oxidoreductase] or D-amino-acid oxidase [EC 1.4.3.3; D-amino-acid: oxygen oxidoreductase] is described in detail. The method is based on the measurement of the ratio of oxygen consumed by the enzyme in the presence of a limited amount of substrate as an internal standard to the total dissolved oxygen, which can be measured by the addition of an excess amount of substrate or sodium hydrosulphite. It was found that this method requires only 1 ml of test water at a temperature between 5 and 40 °C, and gives satisfactory results over a wide range of oxygen concentrations up to 100 per cent. saturation, and the result can be obtained in only 5 minutes. The values found are almost identical with those generally accepted.