Computer optimization of background electrolyte composition in the separation of metal ions by capillary electrophoresis

The iterative regression design developed earlier for high performance liquid chromatography (HPLC) has been applied successfully to the optimization of the separation of 11 metal ions by capillary electrophoresis. The parameters used for optimization were pH (over the range 3.5-5.0) and the concentration of 2-hydroxyisobutyric acid (HIBA) (2-20 mM) used as the complex-forming ligand added to the background electrolyte. Five initial experiments were performed and the response surface was calculated using the relative resolution product as criterion. Three additional experiments were sufficient to establish a stable optimum, with which all 11 metal ions were separated and well spread in the electropherogram. The total analysis time was less than 5 min.