Isotachophoretic determination of bisoprolol, clonidine, disopyramide and tolazoline in human fluids.

Separation and determination of bisoprolol, clonidine, disopyramide and tolazoline in control serum and in human urine was investigated by capillary isotachophoresis. The drugs were separated by using the cationic electrolyte system. viz., sodium acetate buffer (pH 4.64) (c1 = 10 mM)-beta-alanine. The compounds were almost totally isolated from serum by solid-phase extraction using a Sep-Pak C18 cartridge. The recovery of compounds varied from 87 to 99%. The linear calibration range was studied to apply the method to real human fluids. The limit of determination of the drugs was 40.0 micrograms/ml serum. The limit of determination by direct sampling for bisoprolol is 3 micrograms/ml urine.