CAPILLARY ELECTROPHORESIS WITH LASER-INDUCED FLUORESCENCE DETECTION -A SENSITIVE METHOD FOR MONITORING EXTRACELLULAR CONCENTRATIONS OF AMINO-ACIDS IN THE PERIAQUEDUCTAL GREY-MATTER

The use of capillary electrophoresis with laser-induced fluorescence d etection (CE-LIF) for the analysis of microdialysate samples from the periaqueductal grey matter (FAG) of freely moving rats is described. B y employing 3-(4-carboxybenzoyl)-2-quinoline-carboxaldehyde (CBQCA) as a derivatization agent, we simultaneously monitored the concentration s of 8 amino acids (arginine, glutamine, valine, gamma-amino-n-butyric acid (GABA), alanine, glycine, glutamate, and aspartate), with nanomo lar and subnanomolar detection limits. Two of the amino acids (GABA an d glutamate) were analysed in parallel by conventional high-performanc e liquid chromatography (HPLC) in order to directly compare the two an alytical methods. Other CE methods for analysis of microdialysate have been previously described, and this improved method offers greater se nsitivity, ease of use, and the possibility to monitor several amino a cids simultaneously. By using this technique together with an optimise d form of microdialysis technique, the tiny sample consumption and the improved detection limits permit the detection of fast and transient transmitter changes.