Determination of glucose, sucrose, lactose, and ethanol in foods and beverages, using immobilized enzyme electrodes.

An enzyme electrode coupling immobilized oxidase enzymes with a hydrogen peroxide-sensitive electrode is described. An enzyme or enzymes are immobilized in a thin microporous membrane which fits directly over a platinum anode held at +0.700 V relative to a Ag/AgCl2 reference electrode. When an enzyme substrate diffuses into the membrane, hydrogen peroxide is produced. The hydrogen peroxide is then oxidized at the platinum anode, producing an electrical current that is directly proportional to hydrogen peroxide concentration, and hence substrate concentration. Glucose and sucrose in cereal samples, lactose in cheese, and ethanol in beer and wine were determined using enzyme electrodes. Relative precision of replicate analyses was better than +/- 2% and agreement with AOAC methods was good.