ENANTIOMERIC PURITY DETERMINATION OF PROPRANOLOL BY CYCLODEXTRIN-MODIFIED CAPILLARY ELECTROPHORESIS

A capillary electrophoretic method for the enantiomeric purity determi nation of either enantiomer of propranolol was developed using cyclode xtrins as chiral additives and uncoated fused-silica capillaries therm ostated at 15 degrees C. The effect of the type and concentration of c yclodextrin added to a triethanolamine-phosphate buffer (pH 3.0) on ch iral resolution and migration times was studied. The propranolol enant iomers could be separated with all cyclodextrins tested (P-cyclodextri n and seven of its derivatives), except dimethyl-P-cyclodextrin. A par ticularly high resolution value of 4.4 was obtained for propranolol en antiomers with a buffer containing 10 mM carboxymethyl-beta-cyclodextr in. This buffer was selected for testing the enantiomeric purity of pr opranolol, making it possible to reach detection limits of less than 0 .1% for the minor enantiomer. The R enantiomer of propranolol (second migrating) could be quantified at the 0.5% level with good precision ( intra-day R.S.D. = 1.7%) in samples of the S enantiomer (first migrati ng), while the limit of quantification of the latter, when present as an impurity in the R enantiomer, was 0.1%. The method also gave good r esults in terms of linearity and accuracy.