On‐line amperometric assay of glucose, L ‐glutamate, and acetylcholine using microdialysis probes and immobilized enzyme reactors

Abstract A highly selective on‐line, real‐time monitoring system is proposed for amperometric assay of glucose, L‐glutamate, and acetylcholine. The system includes a microdialysis probe, immobilized enzyme reactor, and poly(1,2‐diaminobenzene)‐coated platinum electrode. The analyte in the dialysate from the microdialysis probe is enzymatically converted to produce hydrogen peroxide. The hydrogen peroxide is detected selectively at a poly(l,2‐diaminobenzene)‐coated platinum electrode, without any interference from oxidizable species and proteins. The present method can be successfully applied to in vitro assay of glucose and in vivo monitoring of glucose in rat brains. However, the sensitivity is not sufficient for in vivo monitoring of trace amounts of L‐glutamate and acetylcholine in rat brains.