SIMULTANEOUS DETERMINATION OF GLUCOAMYLASE ACTIVITY AND GLUCOSE IN FERMENTATION PROCESS BASED ON SCREEN-PRINTED DISPOSABLE BIOSENSOR

Screen-printed disposable biosensor with dualcarbon working electrodes and an Ag/AgCl reference electrode was developed for simultaneous determination of glucoamylase (GA) activity and glucose. Such determination can be accomplished in 1 min by immobilizing glucose oxidase (GOD) and GOD/starch onto different working electrodes. The method was based on electrochemical detection of glucoamylase-catalyzed glucose from the starch layer coupling with mediator oxidation. Cyclic voltammetry was employed to demonstrate the principle. Chronoamperometry at + 0.4 V versus Ag/AgCl was performed without incubation time. The linear response ranges were up to 20-mmol/l glucose and 150-U/ml GA. The method was applied to the measurements of glucose and GA activity in fungal fermentation process, and exhibited good agreement with the reference method.