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. Nanomolar concentration of glutamate labeled with naphthalene-2,3-dicarboxaldehyde (NDA) was measured by using capillary electrophoresis and laser-induced fluorescence detection. The limit of mass detection was in the 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 15 mum inside diameter were used. The potential of capillary electrophoresis coupled to laser-induced fluorescence detection for in vivo monitoring of neurotransmitters is discussed.