PARAMETERS INFLUENCING SEPARATION AND DETECTION OF ANIONS BY CAPILLARY ELECTROPHORESIS

Electrolyte composition is critical in optimizing separation and detec tion of ions by capillary electrophoresis. The parameters which must b e considered when designing an electrolyte system for capillary electr ophoresis include electrophoretic mobility of electrolyte constituents and analytes, detection mode, and compatibility of electrolyte consti tuents with one another. An electrolyte system based on pyromellitic a cid is well suited for use with indirect photometric detection, and pr ovides excellent separations of anions. The ability to modify the elec trophoretic mobility of pyromellitic acid as a function of pH provides flexibility in matching electrophoretic mobilities of analytes. Addit ionally, the use of alkyl amines as electroosmotic flow modifiers allo ws the rapid separation of anions by reversing the direction of electr oosmotic flow in a fused-silica capillary. The optimization of a capil lary electrophoresis electrolyte for anion analysis is also discussed in terms of pH, ionic strength and applied voltage. The effect of orga nic solvent on separation selectivity is also discussed.