SUPPRESSED CONDUCTOMETRIC CAPILLARY ELECTROPHORESIS SEPARATION SYSTEMS

A tubular cation-exchange membrane is installed at the end of a 60-cm-long 75-mum-bore fused-silica capillary. A static dilute acid regenerant solution surrounds the membrane that functions as a suppressor. With positive high voltage applied to the capillary inlet and the regenerant solution grounded, effective suppression of electrolytes such as solutions of alkali metal borate, glycinate, or cyanide is observed. Electroosmotic flow carries the capillary effluent past the suppressor into a conductivity detection cell constituted by two platinum wires inserted through the wall of a poly(vinyl chloride) capillary. The system provides detection limits in the 10-20 mug/L range for a variety of anions; a typical separation requires 15 min. Applicability to a variety of real samples is demonstrated.