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How to perform spectrum-based LC-HR-MS screening for more than 1,000 NPS with HighResNPS consensus fragment ions. | LitMetric

How to perform spectrum-based LC-HR-MS screening for more than 1,000 NPS with HighResNPS consensus fragment ions.

PLoS One

Department of Forensic Medicine, Faculty of Health and Medical Sciences, Section of Forensic Chemistry, University of Copenhagen, Copenhagen, Denmark.

Published: January 2021

AI Article Synopsis

  • The study addresses the challenges posed by new psychoactive substances (NPS) for analytical labs and explores the use of the HighResNPS database for more effective spectrum comparison on high-resolution mass spectrometry (HR-MS) instruments.
  • Researchers analyzed 42 NPS samples using two different acquisition methods (DIA and DDA) and evaluated the results through the HighResNPS consensus library, finding that all samples were identified with a high success rate.
  • It was determined that using fractional intensity assignment in spectrum comparison was more advantageous than absolute assignment, as it led to better identification rates and more selective results when distinguishing between similar compounds.

Article Abstract

Introduction: The ever-changing market of new psychoactive substances (NPS) poses challenges for laboratories worldwide. Analytical toxicologists are constantly working to keep high-resolution mass spectrometry (HR-MS) screening libraries updated for NPS. This study sought to use the online crowd-sourced HighResNPS database for spectrum comparison screening, thereby broadening its utility to all HR-MS instruments.

Method: HighResNPS allows formation of a set of consensus fragment ions for a NPS and prioritises among multiple entries of collision-induced fragment ions. A subset of 42 NPS samples was analysed in data-independent acquisition (DIA) and data-dependent acquisition (DDA) modes on two different instruments. HighResNPS-computed spectra were generated with either Absolute (all fragment ions set to 100%) or Fractional (50% intensity reduction of former fragment ion) intensity. The acquired NPS data were analysed using the consensus library with computed ion intensities and evaluated with vendor-neutral screening software.

Results: Overall, of the 42 samples, 100% were identified, with 88% identified as the top candidate. Three samples had the correct candidate proposed as the second highest ranking NPS. In all three of those samples, the top proposed candidate was a positional isomer or closely related compound. Absolute intensity assignment provided identical scoring between the top two proposed compounds in two samples with DIA. DDA had a slightly higher identification rate in the spectra comparison screening with fractional intensity assignment, but no major differences were observed.

Conclusion: The fractional intensity assignment was slightly more advantageous than the absolute assignment. It was selective between proposed candidates, showed a high identification rate and had an overall higher fragmentation scoring. The candidates proposed by the HighResNPS library spectra comparison simplify the determination of NPS for researchers and toxicologists. The database provides free monthly updates of consensus spectra, thereby enabling laboratories to stay at the forefront of NPS screening by LC-HR-MS with spectra screening software.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660508PMC
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0242224PLOS

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