[en] The separation of four beta-blocking drug substances (atenolol, sotalol, betaxolol, and metoprolol) selected as model basic analytes has been investigated in non-aqueous capillary electrophoresis (NACE) using the principle of ion-pair formation. Camphorsulphonate was selected as the counter-ion in a background electrolyte (BGE) made up of formate buffer in a mixture of acetonitrile/methanol or acetonitrile/ethanol. The influence on resolution of the concentration of the counter-ion, the nature and proportion of the organic solvents, as well as the concentration of the ionic components of the BGE was first studied by a univariate approach. An experimental design was then applied to estimate possible quadratic effects and first-order interactions. To identify the most important factors affecting the separation of the four beta-blockers, a two-level fractional factorial design with 16 experimental points was applied as a screening test. A three factor Box-Behnken design with 12 experimental points was used to predict and optimize the selectivity. Finally the optimal conditions obtained by the univariate and the multivariate, approaches were compared.
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS