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 accom plished in 1 min by immobilizing glucose oxidase (GOD) and GOD/starch onto different working electrodes. The method was based on electrochemical detec tion of glucoamylase-catalyzed glucose from the starch layer coupling with mediator oxidation. Cyclic voltammetry was employed to demonstrate the prin ciple. Chronoamperometry at +0.4 V versus Ag/AgCl was performed without inc ubation time. The linear response ranges were up to 20-mmol/l glucose and 1 50-U/ml GA. The method was applied to the measurements of glucose and GA ac tivity in fungal fermentation process, and exhibited good agreement with th e reference method.