CAPILLARY-ELECTROPHORESIS OF ANIONS AT HIGH-SALT CONCENTRATIONS

It is commonly thought that even a moderately high ionic concentration in the background electrolyte (BGE) would leaad to Joule heating and serious peak distortion. However, we obtained very satisfactory separa tions of both inorganic and organic anions in electrolyte solutions as high as 5 M sodium chloride using direct photometric detection. Sampl es containing a 0.5 M concentration of a salt can be analyzed directly by making the BGE concentration of the same salt even higher to obtai n electrostacking. The temperature in the center of the capillary was calculated to be 49 degrees C when the current is at its maximum of 28 0 mu A. The effect of various salts on electrophoretic and electroosmo tic mobility is discussed. Several examples are given of capillary ele ctrophoresis under high-salt conditions.