Measurement of binding constant of host-guest interaction by capillary electrophoresis

The binding constant between beta-cyclodextrin (beta-CD) and the drug alprenolol was obtained by capillary electrophoresis, under the conditions of 100 mmol/L phosphate buffer, pH 2.5, 25 degrees C. Four methods, namely non-linear regression, double reciprocal, gamma-reciprocal and x-reciprocal were introduced to measure the binding constant, the values are 307.2 L/mol, 408.4 L/mol, 331.4 L/mol and 343.1 L/mol, respectively. The methods are applicable to measure the binding constant of Host-Guest interaction with 1:1 ratio.