INVIVO MONITORING OF BRAIN GLUTAMATE BY MICRODIALYSIS COUPLED TO CAPILLARY ELECTROPHORESIS AND LASER-INDUCED FLUORESCENCE DETECTION

A method to measure glutamate in brain dialysates was developed. Nanom olar concentration of glutamate labeled with naphthalene-2,3-dicarboxa ldehyde (NDA) was measured by using capillary electrophoresis and lase r-induced fluorescence detection. The limit of mass detection was in t he zeptomole concentration (10(-21) M) range. The technique was linear between 10(-5) M to 10(-8) M. It was possible to reduce the migration time of brain dialysate glutamate to 60 seconds when capillaries of 1 5 mum inside diameter were used. The potential of capillary electropho resis coupled to laser-induced fluorescence detection for in vivo moni toring of neurotransmitters is discussed.