On the challenge of unambiguous identification of fentanyl analogs: exploring measurement diversity using standard reference mass spectral libraries

Published

July 11, 2023

Author(s)

Arun Moorthy, Edward Erisman, Anthony J. Kearsley, Yuxue Liang, Edward Sisco, William E. Wallace

Abstract

Fentanyl analogs are a class of designer drugs that are particularly challenging to unambiguously identify due to the mass spectral and retention time similarities of unique compounds. In this paper, we use agglomerative hierarchical clustering to explore the measurement diversity of fentanyl analogs and better understand the challenge of unambiguous identifications using analytical techniques traditionally available to drug chemists. We consider four measurements in particular: gas chromatography retention indices, electron ionization mass spectra, electrospray ionization tandem mass spectra, and direct analysis in real time mass spectra. Our analysis demonstrates how simultaneously considering data from multiple measurement techniques increases the observable measurement diversity of fentanyl analogs, which can reduce identification ambiguity. This paper further supports the use of multiple analytical techniques to identify fentanyl analogs (among other substances), as is recommended by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG).

Citation

Journal of Forensic Sciences

Volume

68

Issue

5

Pub Type

Journals

Download Paper

https://doi.org/10.1111/1556-4029.15322

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Keywords

agglomerative hierarchical clustering, direct analysis in real time mass spectrometry, electron ionization mass spectrometry, electrospray ionization tandem mass spectrometry, fentanyl analogs, gas chromatography retention indices, mass spectral libraries, measurement diversity

Citation

Moorthy, A. , Erisman, E. , Kearsley, A. , Liang, Y. , Sisco, E. and Wallace, W. (2023), On the challenge of unambiguous identification of fentanyl analogs: exploring measurement diversity using standard reference mass spectral libraries, Journal of Forensic Sciences, [online], https://doi.org/10.1111/1556-4029.15322, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936752 (Accessed October 8, 2025)