Flow-injection analysis-wall-jet electrode system for monitoring glucose and lactate in fermentation broths

Abstract

A novel and straightforward approach for the monitoring of glucose and lactate in fermentation broths based on flow-injection analysis (FIA) coupled with a wall-jet electrode (WJE) is described. Glucose or lactate present in the fermentation broths was converted to hydrogen peroxide by immobilised glucose oxidase or lactate oxidase respectively. The hydrogen peroxide was then detected anodically by a platinum wall-jet electrode at +0.65 V (vs. Ag/AgCl, saturated KCl). For the FIA-WJE, a linear response was obtained for hydrogen peroxide ranging from 1.00 × 10-7 M to 100 × 100-3 M, with a detection limit of 1.00 × 10-8 M for hydrogen peroxide based on a signal-to-noise ratio of 3. The range of glucose which can be measured by this FIA-WJE system was 5.67 × 10-5 M to 2.78 × 10-3 M, while the range for lactate was 2.22 × 10-5 M to 5.56 × 10-4 M. Interferences from the fermentation media were observed but could be eliminated by pretreatment of the electrode with Fe2+. The electrode response showed good stability and reproducibility after pretreatment. The system was used to monitor the glucose and lactate concentrations in different fermentation broths both for bacteria cell lines cultivation and for mammalian cell lines cultivation. The results showed good agreement with those determined by a commercial glucose-lactate analyzer. © 1993.