A liquid chromatographic method for the determination of promethazine enantiomers in human urine and serum using solid-phase extraction and fluorescence detection.

A LC method was developed for the concurrent assay of R(+) and S(-) promethazine from human urine and serum. The method involves the use of solid-phase extraction for sample clean-up. Chromatographic resolution of the enantiomers was performed under isocratic conditions using a mobile phase of hexane-1,2-dichlorethane-absolute ethanol-trifluoroacetic acid (400:150:100:1, v/v/v/v) at a flow rate of 1 ml min-1 on a brush-type column KK-CARNU. The enantiomers were detected by fluorescence using an excitation wavelength of 250 nm and a 280 nm emission cutoff filter. Chlorpromazine was used as the internal standard for urine analysis. Standard addition was used for promethazine analysis from serum. Drug to internal standard ratios were linear from 0.25 to 10 micrograms ml-1 in urine. Serum levels were linear from 2 to 10 ng ml-1.