Analytical Sciences

Simultaneous Determination of L-Glutamate, Acetylcholine and Dopamine in Rat Brain by a Flow-Injection Biosensor System with Microdialysis Sampling

Toshio YAO and Gen OKANO

Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuencho, Naka, Sakai, Osaka 599-8531, Japan

A flow-injection biosensor system with an on-line microdialysis sampling system is proposed for the simultaneous detection of neurotransmitters (L-glutamate, acetylcholine and dopamine) released from rat brain cells. The dialysate collected in the sample loop from the microdialysis probe was automatically injected into the flow-injection line with a triple electrode arranged perpendicular to the flow direction. The triple electrode was constructed by hybridizing a poly(1,2-diaminobenzene) film to two enzyme sensing-parts which respond to L-glutamate and acetylcholine, and by coating a Nafion film on a remaining sensing part which responds to dopamine, respectively, without any cross-reactivity. The three sensing parts of the triple electrode responded linearly to the concentrations of L-glutamate and acetylcholine in the range of 0.002 - 5 mM and to that of dopamine in the range of 0.002 - 20 mM, respectively, without any interference from oxidizable species present in the dialysate. The proposed flow-injection analytical method could be applied to an in vivo assay of these neurotransmitters released from rat-brain cells by the continuous KCl stimulation.

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