PHARMACEUTICAL AND BIOMEDICAL APPLICATIONS OF CAPILLARY ELECTROPHORESIS ELECTROCHEMISTRY/

The use of capillary electrophoresis/electrochemistry (CEEC) for the a nalysis of microdialysis samples obtained for pharmacokinetic and neur ochemical studies is described, as well as the development of new type s of electrodes and waveforms which increase the selectivity of this t echnique for specific classes of analytes. CEEC with a carbon fiber el ectrode was employed for the analysis of microdialysis samples. Microd ialysis is an in vivo sampling technique that yields very small sample s for analysis (less than 1 mu L). Therefore, capillary electrophoresi s, with its small volume requirements, is an excellent choice for the analytical method. CEEC was used to study the pharmacokinetics of L-do pa and the release of aspartate and glutamate following a high K+ infu sion in the brain. Several modified electrodes which increase the appl icability of CEEC in pharmaceutical and biomedical analysis are descri bed. One of these is a gold/mercury electrode which is highly selectiv e for thiols and was used for the determination of glutathione in a ra t brain. An alternative method for the detection of thiols employed a chemically modified electrode containing cobalt phthalocyanine. In thi s case, an electrocatalyst reduces the overpotential of thiols at the carbon electrode and makes it possible to detect them at a much lower and more selective oxidation potential. This electrode was used for th e detection of cysteine in urine. The development of pulsed amperometr ic detection for capillary electrophoresis is also described and is de monstrated by the detection of glucose in blood. Lastly, a method for the detection of peptides based on the formation of a copper complex a nd detection at a carbon fiber electrode is discussed.