Determination of glucose oxidase activity of flour additive by fluorescence quenching method

Glucose oxidase can catalyze the reaction of glucose to produce hydrogen peroxide, and hydrogen peroxide reacts with excess I⁻ anions in dilute sulfuric acid solution to form I₃⁻. The I₃⁻ combines with Rhodamine 6G to form association which result in fluorescence quenching. Effect of glucose oxidase on fluorescence of Rhodamine 6G, a new method with high sensitivity and good selectivity for the determination of glucose oxidase activity, was established. Under the optimal conditions, the linear range of the method is 1.0 × 10^–4–1.0 × 10^–1 U/mL, and the detection limit is 9.0 × 10^–5 U/mL. This assay was applied to the determination of glucose oxidase activity in the food additives samples with satisfactory results; the recoveries obtained were 96.67–99.00%.