SELECTIVE DETECTION OF FREE THIOLS BY CAPILLARY ELECTROPHORESIS ELECTROCHEMISTRY USING A GOLD MERCURY AMALGAM MICROELECTRODE

A thiol-specific detector for capillary electrophoresis which employs a gold/mercury amalgam microelectrode has been developed. The detection method is based on the catalytic oxidation of mercury in the presence of thiols. Detection limits for glutathione are 0.53 fmol (or 2.1 X 10(-8) M). Deoxygenation of the system was important for reproducibility of response. Under deoxygenated conditions, the RSD for 20 injections was 2.1 %. The electrode can easily be regenerated in situ by electrodeposition or by removing and dip-coating with mercury. The use of this method for the separation and detection of a number of biologically important thiols is reported.