Achiral-chiral column switching HPLC assay was developed to allow the separ
ation and quantitation of the enantiomers of metoprolol in human urine by m
eans of fluorescence detection. Urine samples were prepared by liquid-liqui
d extraction, followed by HPLC. The racemic metoprolol and internal standar
d were separated from the interfering components in urine and quantified on
the silica column, and the enantiomers were determined on a Chiralcel OD c
hiral stationary phase. The two columns were connected by a switching valve
equipped with a silica trap column. Detection limit was 25 ng/ml for each
enantiomer. The intra-day variation ranged between 0.38 and 4.94% in relati
on to the measured concentration and the inter-day Variation was 0.15-3.13%
. It has been applied to the determination of (R)-(+)-metoprolol and (S)-(-
)-metoprolol in urine from healthy volunteers dosed with racemic metoprolol
tartrate. (C) 2000 Elsevier Science B.V. All rights reserved.