Determination of Apparent Dissociation Constants of β-Agonists by Capillary Electrophoresis

In this study, the electrophoretic behaviour of 4 β-agonists: clenbuterol (CLB), salbutamol (SAL), terbutaline (TER) and ractopamine (RAC) was investigated by capillary zone electrophoresis at different pH range (8-12). It was found that CLB possessed the character of monoprotic protonated base, while SAL TER and RAC had the character of amphoteric compound. The dissociation constants of CLB、SAL、TER、RAC were determined by nonlinear curve fitting through the derivation of nonlinear relationship between the effective electrophoretic mobility (μeff) of different analytes and the pH of buffer solution.