Postmortem drug screening by non-targeted and targeted ultra-performance liquid chromatography-mass spectrometry...

In the medical examiner setting, comprehensive drug screening is an essential analytical tool in the investigation of cause and manner of death.We have validated non-targeted and targeted screening assays for drugs and metabolites using ultra-performance liquid chromatography (UPLC) interfaced with mass spectrometry (MS) in single and tandem stages. For non-targeted screening by UPLC-MS electrospray interface, in-source fragmentation was used along with MS scanning (m/z 80-650) and library search for over 700 drug and metabolite analytes. Targeted detection of over 200 analytes by UPLC-MS-MS was performed with dual transition ion monitoring. Validation studies confirmed reproducibility of both mass spectra produced by in-source fragmentation and transition ion ratios by collision-cell dissociation. Lower limit of detection by UPLC-MS (10-150 ng/mL) and UPLC-MS-MS (1-50 ng/mL) was determined for a subset of drugs and correlated with extraction recovery and matrix effect. Drug findings by UPLC-MS and UPLC- MS-MS were compared with gas chromatography-mass spectrometry (GC-MS) screening in postmortem blood from 410 medical examiner cases with 1121 positive drug findings by all methods. Accuracy, based on results of confirmation testing, was high (98-99%) across all screening assays and detection sensitivity by GC-MS (71%), UPLC-MS (73%), and UPLC-MS-MS (76%) was determined. UPLC-MS plus UPLC-MS-MS screening resulted in the highest drug detection rate (95%) and provided optimal dual-screening for the postmortem casework.