A new method of large volume sample stacking with acetonitrile was used for determination of ?-aminobutyric acid (GABA), glycine (Gly) a glutamate (Glu) in the microdialyzate of central nervous system by capillary electrophoresis with contactless conductivity detection. A pressure is applied to remove the interfering acetonitrile zone out of the capillary during separation.
This technique enables to increase the injected sample amount up to 98% of total capillary length. Under optimized conditions LODs achieve 9, 10 and 15 nM for GABA, Gly and Glu in model sample and 29, 29 a 37 nM in microdialyzate samples.