Comparative Evaluation of Low- and High-Resolution MS Approaches for Screening and Confirmation of New Psychoactive Substances in Human Specimen Matrices

New psychoactive substances (NPS) are emerging compounds that are analogs of controlled substances and marketed to evade law enforcement control. The rapid emergence of NPS represents a challenge in forensic toxicology laboratories tasked with detection and identification of NPS in both ante- and post-mortem testing. Traditional screening methods, such as immunoassays and gas chromatography-mass spectrometry (GC-MS) are not highly reliable for NPS detection. Thus, there is a critical need to develop rapid and comprehensive screening methods that will provide unequivocal identification of NPS compounds. The most promising current approach is analysis by liquid chromatography (LC) coupled to either low-resolution MS (LRMS) or high-resolution MS (HRMS). The general approach to NPS analysis also includes two categories; “targeted” and “non-targeted” analysis. Despite the availability and use of different MS-based screening approaches in forensic toxicology laboratories, there is little published data evaluating the comparative performance and reliability of LRMS and HRMS approaches for targeted and untargeted screening of NPS in human specimen matrices. Consequently, the proposed work will rigorously evaluate the comparative analytical performance of LRMS (triple quadrupole MS) vs. HRMS (QTOF-MS) for targeted screening/confirmation of NPS and of two HRMS instrument platforms (QTOF and Q-orbitrap) for untargeted screening/confirmation of NPS. These comparisons will be conducted using three important human specimen matrices; whole blood, urine, and oral fluid (OF). The project goals will be completed in three tasks. Task 1 involves comparison of the performance of LC-QqQ-MS and LC-QTOF-MS platforms for targeted analysis of an NPS test mixture containing 40 analytes in whole blood, urine, and OF. Task 2 involves comparison of performance of LC-QTOF-MS and LC-Q-orbitrap-MS platforms for non-targeted analysis of NPS utilizing the NPS test mixture in whole blood, urine, and OF. Task 3 will test applicability by screening of blind spiked and authentic specimens, with a focus on detectability and identification efficiency of NPS. The outcomes of this project will have relevant applications in the fields of forensic science, forensic toxicology and law enforcement. Many forensic toxicology laboratories are implementing changes to NPS screening by a shift from immunoassays and GC-MS to LC-MS based approaches. Unfortunately, current data do not allow reliable comparisons of NPS identification performance for the various available MS platforms, workflows, and data processing approaches. The proposed project will generate data that will assist forensic laboratories in making informed decisions about which approach to implement in their laboratory for identifying these increasingly important illicit substances.