Determination of the β-blocker atenolol in plasma by capillary zone electrophoresis

A capillary zone electrophoretic method was optimised for the determination of the β-blocker atenolol in plasma. Separation was performed in an uncoated silica capillary of 58.5 cm (effective length 50 cm)×75 μm I.D., and detection was at 194 nm. The effects of the buffer (concentration and pH), the injection time, the voltage applied and the plasma clean-up procedure were studied. The determination of atenolol was achieved in less than 3 min, using an electrolyte of 50 mM H3BO3–50 mM Na2B4O7 (50:50, v/v) pH 9, injected hydrodynamically for 4 s at 50 mbar and applying a voltage of +25 kV. This method was applied to the determination of atenolol in plasma of nine hypertensive patients (male and female, aged from 39 to 73 years). Atenolol concentrations found vary from 30 to 585 ng/ml.