Quantification of acetaminophen and two of its metabolites in human plasma by ultra-high performance liquid chromatography–low and high resolution tandem mass spectrometry

The quantification of acetaminophen (APAP) and two of its metabolites, i.e. acetaminophen-glucuronide (APAP-GLUC) and acetaminophen-cysteine (APAP-CYS), is described in human plasma using ultra-high performance liquid chromatography coupled to a triple quadrupole linear ion trap mass spectrometer operating in the selected reaction monitoring (SRM/MS) mode and to a high resolution quadrupole time-of -flight mass spectrometer operating in the MS/MS (HR-SRM/MS) mode. Starting with a 50 μL plasma aliquot, a generic sample preparation was performed using protein precipitation with methanol/ethanol. Both methods were found to be linear over 2.5 orders of magnitude. Similar performances to the SRM/MS assay were obtained for APAP, APAP-CYS and APAP-GLUC using high resolution-selected reaction monitoring mode with LLOQ of 20, 50 and 50 ng/mL, respectively. For all analytes, precision was found to be better than 12% and accuracy in the range 90.3–109%. The present study demonstrates the ability of QqTOF platforms for accurate and precise quantification in MS/MS mode using short duty cycle with similar sensitivity to LC–SRM/MS. Additionally, as full scan data MSALL are available qualitative and quantitative information on metabolites can also be obtained in a single LC–MS run.