Analysis of Urinary Metabolites of Acetaminophen, Dextromethorphan, and Doxylamine by Liquid Chromatography/High Resolution Time-of-Flight Mass Spectrometry

This application note demonstrates the use of the LECO Citius LC-HRT for the identification of xenobiotic urinary metabolites. The high resolution allowed sensitive detection of metabolites in the presence of abundant chromatographic interference. In one case, a metabolite could be clearly detected under the presence of a more abundant co-eluting isobar separated by about 15 mDa. Pulsed in-source collision-induced dissociation allowed monitoring of characteristic fragment ions to facilitate detection of doxylamine metabolites. Accurate mass measurement and accurate isotopic patterns allowed confident assignment of elemental composition. All this information was obtained from a single chromatographic analysis, demonstrating several advantages of high resolution time-of-flight mass spectrometry.