In the present work an isocratic enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the separation and quantitative determination of dextro - and levo -methorphan and their pharmacologically relevant metabolites, dextrorphan and levorphanol, respectively, in human blood samples. The separation of enantiomers of methorphan and metabolites was performed on the polysaccharide-based chiral column Lux AMP in combination with acetonitrile and 5 mM aqueous ammonium bicarbonate pH 11 in the ratio 50:50 (%, v/v) as mobile phase with the flow rate 1 mL/min. The mass spectrometer was operated in scheduled multiple reaction monitoring (MRM) mode, with four transitions for each dextromethorpan, levomethorphan, dextrorphan and dextromethorphan-d3 and two transitions for each levorphanol, levorphanol-d3 and dextrorphan-d3. Application of this method to human post-mortem blood samples confirmed cases of severe overdosing with dextromethorphan, levomethorphan, and less commonly with both.
Keywords: Dextromethorphan; Dextrorphan; Enantioselective analysis; Levomethorphan; Levorphanol.
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