Determination of glutamate in rat brain microdialysates by microbore liquid chromatography with electrochemical detection

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