Bioanalytical experiments for the undergraduate laboratory : monitoring glucose in sports drinks

This paper describes two complementary bioanalytical experiments for analyzing the concentration of glucose in sports drinks. The first experiment is a spectrophotometric enzyme assay employing the enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP). The glucose is oxidized by the GOx, producing hydrogen peroxide, which is the substrate for HRP. In the reduction of the H2O2 a chromogen is oxidized, causing a color change. In the partner experiment, the GOx is immobilized on a platinum electrode using a dialysis membrane. The hydrogen peroxide produced in the enzyme reaction is monitored amperometrically by oxidizing the hydrogen peroxide produced. The simple method of preparing the enzyme electrode is useful in demonstrating the important parameters in defining the response of enzyme electrodes. The same sports drinks are analyzed in both experiments. The two experiments together illustrate the advantage of bioanalysis in analyzing complex samples with minimal sample preparation.