CAPILLARY ZONE ELECTROPHORETIC METHOD FOR THE QUANTITATIVE-DETERMINATION OF THE BETA-BLOCKER ATENOLOL IN HUMAN URINE

A simple capillary zone electrophoresis method was developed for the q uantitation of the beta-blocker 4-[2-hydroxy-3-[(1 -methylethyl)amino] propoxy] benzeneacetamide, atenolol. The electrophoretic separation wa s performed using a 78 cm x 75 mu m I. D. fused silica capillary. The electrolyte consisted of a buffer Na2HPO4 (25mM)-Na2B4O7 (25 mM) (50-5 0; V/V), pH 9.7. The introduction of the sample was made hydrostatical ly for 25 s and the running voltage was 20 KV at the injector end of t he capillary. Photometric detection was used and a wavelength of 214 n m. The method was applied to the determination of atenolol in urine sa mples obtained from a hypertensive patient under medical treatment wit h the pharmaceutical formulation ''Tenormin 100 mg'' (atenolol 100 mg) , another patient under treatment with the pharmaceutical combination ''Tenoretic'' (atenolol 100 mg + chlorthalidone 25 mg), and also in ur ine samples obtained from a healthy volunteer after the ingestion of a 100 mg atenolol tablet, ''Tenormin 100 mg''. Using a simple solid pha se extraction, a recovery of 70.69+/-3.27% and a very good separation from the urine matrix are achieved. A good reproducibility, linearity, and accuracy are obtained, and a quantitation limit of 0.1 mu g/mL in urine, allows the method to be applied to pharmacokinetic studies of the compound.