Determination of GABA, glutamate, dopamine and carbamathione in brain microdialysis samples by micellar electrokinetic chromatography and laser-induced fluorescence (MEKC-LIF)

Abstract

A micellar electrokinetic chromatography and laser-induced fluorescence (MEKC-LIF) method based on derivatization with naphthalene-2,3-dicarboxyaldehyde (NDA) was optimized to separate and detect glutamate (Glu), gamma-aminobutyric acid (GABA), dopamine (DA) and carbamathione in brain microdialysis samples. The background electrolyte (BGE) consisted of 22.5 mmol L⁻¹lithium tetraborate, 25 mmol L⁻¹lithium dodecylsulfate and 10% methanol. The separation was carried out on a 65 cm × 50 μm id fused-silica capillary (50 cm effective) at +15 kV voltage with a run time of 25 min. The detection limits for GABA, Glu, DA and carbamathione were 6, 10, 5 and 10 nmol L⁻¹, respectively. This method was used to monitor GABA, Glu, DA and carbamathione in brain microdialysis samples from the nucleus accumbens after the administration of an intra-peritoneal dose of disulfiram (200 mg kg⁻¹) and revealed a disulfiram-induced change in GABA, Glu and DA levels. This method demonstrates a simple, rapid and accurate measurement of three amino acid neurotransmitters and carbamathione for in vivo monitoring in the brain using microdialysis sampling.