Simultaneous determination of the active ingredients in composite pseudoephedrine hydrochloride tablets by capillary electrophoresis

A simple, rapid and specific capillary electrophoresis (CE) method has been developed for the separation and determination of pseudoephedrine hydrochloride (PSED), paracetamol (PRCT) and dextromethorphan hydrochloride (DEMP) with UV detection. The CE was performed in 20 mmol/l sodium phosphate buffer solution (pH 7.0). The three ingredients were completely separated within 5 min, and quantified with an UV-detector at 200 nm. Relative standard deviations of 0.85% for PSED, 3.90% for PRCT and 0.84% for DEMP were achieved for seven injections of the sample containing about PSED of 30 μg/ml, PRCT of 325 μg/ml and DEMP of 15 μg/ml. The excellent linearity was obtained in the concentration range 300.0–2.5 μg/ml for PSED, 500.0–5.0 μg/m for PRCT and 500.0–10.0 μg/m for DEMP. The detection limits for PSED, PRCT and DEMP were 0.75, 1.20 and 2.50 μg/ml, respectively. The proposed method has been applied to the monitoring of commercial composite pseudoethedrine tablets and biological sample (urine). The analytical results were satisfactory.