[Determination of the pKa value of icariin and its content in the Chinese herb medicine epimedium grandiflorum morr. by capillary electrophoresis].

Knowledge of dissociation constants is important for prediction and understanding the migration behavior of analytes in capillary electrophoresis. Icariin is the active component of the Chinese herb medicine Epimedium grandiflorum Morr.. In order to determine the dissociation constant of icariin and to show many important pharmacology activities, a CZE method has been used to determine the ion mobility (mu A-) and the pKa value of icariin based on the non-linear relation between mu eff and [H+] and the linear relation between the reciprocal of effective mobility of the solute (1/mu eff) and the [H+] of the buffer solution. In addition, the change of pKa of icariin with the increase of ethanol concentration in the buffer was also investigated. Under the buffer condition of 24 mmol/L phosphate + 30% ethanol, the content of the active component icariin in Chinese herb Epimedium grandiflorum Morr. was quantitatively determined. The linear correlation equation was Y = 6.96 x 10(-3) + 17.0X, and the linear range is 0.032 g/L-0.354 g/L.