Separation of basic proteins in free solution capillary electrophoresis: Effect of additive, temperature and voltage

A comparative study on the separation of basic proteins using different buffer additives in free solution capillary electrophoresis is presented. Five additives, potassium chloride, morpholine, cetyltrimethylammonium bromide (CTAB), poly(vinyl alcohol) and polyethyleneimine, used to reduce the adsorption of the proteins onto the capillary wall were tested. The study was done at different concentrations of additive, voltages and temperatures of separation. The advantages and drawbacks of each additive are discussed. From our study, it is deduced that the use of CTAB renders the best protein separations provided that adequate additive concentration, run voltage and, more interestingly, temperature of separation are chosen. Using this simple procedure, efficiencies higher than 300 000 theoretical plates per meter were obtained for the separation of basic proteins under optimized conditions.