DETERMINATION OF GLUTAMATE IN RAT-BRAIN MICRODIALYSATES BY MICROBORE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

A highly sensitive microbore liquid-chromatographic method with electr ochemical detection has been developed for the determination of glutam ate in rat brain dialysates. Isocratic separation of glutamate was ach ieved using a microbore reversed phase C-18 column and a 100 mM Na2HPO 4-methanol (60:40, v/v, adjusted to pH 5.0 with orthophosphoric acid) mobile phase. A hydrodynamic voltamogram was generated (300-900 mV) fr om which an optimal working potential of +600 mV was established. The absolute detection limit of glutamate was 17 fmol (signal-to-noise rat io of three). This system offers the significant advantages of small s ample consumption and improved detection limits compared with conventi onal liquid chromatographic applications. These factors permit greater sampling frequency and better temporal resolution between ex-vivo bra in neurochemistry and measures of behavioural performance.