Anal. Chem. 1999, 71, 2379-2384
Rapid Determination of Aspartate Enantiomers in Tissue Samples by Microdialysis Coupled On-Line with Capillary Electrophoresis Jonathan E. Thompson, Thomas W. Vickroy, and Robert T. Kennedy*
Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200
Microdialysis was coupled on-line with derivatization by o-phthalaldehyde and β-mercaptoethanol and optically gated capillary electrophoresis to determine D- and Laspartate in tissue samples obtained from rats. The microdialysis probe was inserted into a homogenized tissue sample which allowed generation of a continuous sample stream that was filtered and deproteinated. With 7.5 mM β-cyclodextrin (CD) in the electrophoresis buffer, the enantiomers of interest could be resolved in 3 s with an electric field of 2500 V/cm over a separation length of 15 mm. Values of D- and L-aspartate in different tissues agreed well with those obtained by an HPLC procedure that required protein precipitation, centrifugation, and extraction. The speed and compatibility with automation of the microdialysis/CE method may make it a general approach for a variety of applications involving highthroughput analysis or sensorlike operation. High-speed, high-efficiency separations by capillary electrophoresis (CE) have recently been made possible by instrumentation such as flow gates, optical gates, and microfabricated systems that allow precise injections of picoliter volumes onto columns with inner diameters of
