Automatic enzymatic determination of glucose with a potentiometric sulphur dioxide probe

An automatic, continuous-flow system for the determination of glucose is reported, with a sulphur dioxide probe used as the sensor for an indicator reaction with hydrogensulphite. In the presence of glucose oxidase, glucose is selectively oxidised to produce hydrogen peroxide at a rate proportional to the glucose concentration. The oxidation of hydrogensulphite by the hydrogen peroxide is rapidly monitored by the probe at sampling rates as high as 90 samples per hour. Proteins and reducing substances, such as cysteine, uric acid and ascorbic acid interfere only in large amounts. The method is applicable to biological fluids without prior separation steps.