Quantitation of model digestive mixtures by 13C NMR

Micellar electrokinetic capillary chromatography determination of +S and -R arotinolol in serum using UV detection and solid phase extraction

A method for the simultaneous determination of +S and -R arotinolol in serum by micellar electrokinetic capillary chromatography is described. Stereoselective resolution of the arotinolol enantiomers was achieved using 5 mM sodium taurocholate in 10 mM sodium dihydrogen phosphate buffer of pH 2.5. A 72-cm uncoated fused-silica capillary at a constant voltage of 15 kV was used for the analysis. The analytes of interest were extracted from serum using solid phase extraction. An octadecyl cartridge gave good recoveries in excess of 87% for both +S and -R arotinolol without any interference. The calibration curves were linear over the range of 50-500 ng ml(-1) with +S propranolol as the internal standard and the coefficient of determination was greater than 0.999 (n = 3). The limit of quantitation was 50 ng ml(-1) for each enantiomer and the detection limit using 1 ml serum and a UV detection set et 220 nm was 25 ng ml(-1) (S/N = 2). Precision and accuracy of the method were in the range 0.8-2.7% and 1.2-6.4%, respectively, for +S arotinolol and 1.1-3.9% and 2.2-6.5%, respectively, for -R arotinolol.