Determination of captopril and its degradation products by capillary electrophoresis.

Captopril, an antihypertensive agent, and its degradation products have been quantified in pharmaceutical formulations by capillary zone electrophoresis (CZE). A method using cetyltrimethylammonium bromide (CTAB) added to a sodium phosphate buffer (pH 5.5; 100 mM) as running buffer and using N-acetyl-L-tyrosine as an internal standard has been developed and validated for the quantitative determination of captopril in tablets. The method is an indicator of compound stability and can also be applied to the purity control of the raw material and for the determination of the degradation products. For this purpose, salicylic acid is used as an internal standard.