Separation of alkylbenzyl quaternary ammonium compounds by capillary zone electrophoresis - Effect of organic solvent in sample solution

The important role played by the organic solvent in the sample solution in the capillary electrophoretic separation of alkylbenzyldimethyl ammonium compounds (ABDACs) is demonstrated. An organic solvent must be added to disrupt the micelles in the sample solution for effective separation of ABDACs. An organic solvent must also be added to the background electrolyte to disrupt micelles. Typically, methanol at a minimal content of 60% (v/v) Or acetonitrile at 30% (v/v) is necessary for complete micelle disruption of a sample at a concentration 0.01 mM when using a phosphate buffer (20 mM) containing 30-40% (v/v) acetonitrile at pH 5.0. The effect of organic solvent in the sample solution is interpreted in terms of the absorption of organic solvents by micelles and the disruption of micelles into individual surfactant ions. The extent of disruption of micelles depends on the concentration of the sample. For complete disruption of micelles of ABDACs in a polar non-aqueous solvent, acetonitrile (40%, v/v) must be added to the phosphate buffer.