Characterization of a thermophilic L-glutamate dehydrogenase biosensor for amperometric determination of L-glutamate by flow injection analysis

摘要

Carbon paste wax electrodes incorporating thermophilic L-glutamate dehydrogenase, NADP and a polymeric toluidine blue O (poly-TBO) mediator have been characterized for the amperometric determination of L-glutamate at 313-318 K in a flow injection analysis (FIA) system. The biosensors exhibit good sensitivity, mechanical stability and reproducibility, unlike carbon paste- or carbon wax-based electrodes under the same conditions. The carbon paste wax electrode responds linearly to L-glutamate up to 40 mM, the detection limit is 0.3 mM and the RSD (n identical with 10) for 5 mM L-glutamate was 7.6%. The response to some potential interferents has been quantified. Addition of finely ground hexaammineruthenium (III) trichloride ([Ru(NH sub(3)) sub(6)]Cl sub(3)) to the carbon paste wax electrodes decreases the FIA peak width and increases the peak current. The metal complex appears to accelerate the rate of oxidation of NAD(P)H by poly-TBO.