Chemically immobilised tri-enzyme electrode for the determination of sucrose using flow injection analysis

Abstract

Invertase, mutarotase and glucose oxidase were co-immobilised on a nylon mesh which was then placed over a platinum electrode. This electrode was used in the amperometric mode in a three-electrode Stelte cell adapted for flow injection analysis for monitoring the hydrogen peroxide enzymolysis product. The optimum enzyme composition (I.U. ratios) for immobilisation on the nylon net of invertase-mutarotase-glucose oxidase was found to be in the ratio 2000 : 1000 : 200. The system exhibited good linearity in the range 10^–6–10^–3M sucrose, short response times (10–20 s), a long lifetime (6% reduction in signals after >14 h continuous flow of fresh 1 mM sucrose) and good storage stability (38 d, stored in 0.1M pH 7 phosphate buffer at 4 °C). The nylon mesh enzyme electrode response and excellent resistance towards radiation, i.e., sterilisation (2.1 Mrad of ⁶⁰Co γ-source), indicated its potential use for on-line monitoring of sucrose in clinical and food-processed samples.