Development of a sequential injection analysis system for the simultaneous biosensing of glucose and ethanol in bioreactor fermentation

An on-line sequential injection analysis system using amperometric detection for the simultaneous monitoring of glucose and ethanol in fermentations media is presented. The automatic analytical procedure developed is based in a sequential injection analysis (SIA) strategy and uses catalytic reactors of oxidase enzymes immobilized on controlled-pore glass. The proposed method allows the simultaneous determination of glucose (linear range between 5 and 750 mg dm−3 with a RSD better than 1.2%) and ethanol (linear range between 0.15 and 30 mg dm−3 with a RSD better than 2.2%). It was applied to monitor both species in beer fermentation. In a way to adjust the levels of ethanol present in the broth to the characteristics of the proposed system a dialysis unit was used between fermenter and SIA manifold. The sampling rate optimized was 50 samples h−1.