Clarithromycin as a chiral selector for enantioseparation of basic compounds in nonaqueous capillary electrophoresis.

The first use of macrolide antibiotic clarithromycin (CLM) in nonaqueous media for enantioseparation (partial or baseline) of the following compounds: alprenolol, atenolol, metoprolol, clenbuterol, methoxyphenamine, pindolol, propranolol, sotalol, synephrine, labetalol, and fenoterol is reported. Each analysis took less than 15 min. To find optimal separation conditions, some properties of CLM (adsorption, solubility), as well as the effect of experimental parameters on the enantioseparation of analytes (background electrolyte composition, chiral selector concentration, temperature, and applied voltage) were studied. The best chiral resolution was achieved in methanolic solution of 100 mM citric acid, 10 mM NaOH, 240-300 mM H3 BO3 , and 60-75 mM CLM. Using the proposed procedure, adsorption of CLM on the capillary wall was negligible and the repeatability of the migration times (RSD) was as good as 1.6%. For the analysis of propranolol, the linearity was achieved in the concentration range 2.5 × 10(-2) - 3.0 × 10(-1) mg/mL with the LODs (3 × S/N) being equal 2.6 × 10(-3) mg/mL and 2.8 × 10(-3) mg/mL for the first and the second enantiomers, respectively. Linear range for metoprolol enantiomers was 1.0 × 10(-2) -1.6 × 10(-1) mg/mL. The LODs (3 × S/N) were determined as 2.8 × 10(-3) and 3.0 × 10(-3) mg/mL for the first and the second enantiomers, respectively.