Capillary electrophoresis separation of vinpocetine and related compounds:Prediction of electrophoretic mobilities in partly aqueous media

Offord's equation, a relationship between electrophoretic mobility and char ge, size and shape of peptides, has been extended to quantitate the electro phoretic mobility of vinca alkaloids. Partly aqueous protonation constants and the derived theoretical mobilities have been proven to be able to predi ct experimental electrophoretic mobilies. In practice, seven vincamine deri vatives of very low water-solubility were separated by capillary electropho resis. Buffer total concentration, apparent pH and methanol content, the th ree most important parameters of the running buffer, were used in triangula r resolution mapping to characterize separation. Even though electrophoresi s is well known to slow down in partly aqueous media, under our optimized c ircumstances a baseline separation was achieved within 8 min in each case.