Nonaqueous capillary electrophoresis: Application possibilities and suitability of various solvents for the separation of basic analytes

Eleven organic solvents were tested for their suitability in the use of cap illary electrophoresis (CE). In all cases, 25 mM ammonium acetate and 1 M a cetic acid were used as electrolytes. Three basic therapeutical agents, pro pranolol, carteolol and imipramine, were used as analytes. Four solvents (2 -propanol, ethylene glycol, propylene glycol, dichloromethane) were not sui table for use with CE under our conditions. Depending on the other solvents used, the analytes showed very different behavior. We observed that the ep silon/eta quotient alone is not sufficient for a characterization of the so lvents. Further investigations with all the solvents as 1:1 mixtures with m ethanol were carried out. As a result some principal changes occurred compa red to the pure solvents. Working with mixtures of different solvents prove d to be advantageous because of the possibility to influence properties lik e high viscosity or low ionizing abilities by the addition of a suitable se cond solvent.