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. Author manuscript; available in PMC: 2021 Mar 1.
Published in final edited form as: Toxicol Lett. 2019 Dec 5;320:87–94. doi: 10.1016/j.toxlet.2019.12.007

Figure 3.

Figure 3.

Comparison of fragmentation spectra between A) acetylfentanyl and its reference standard within the library, and B) 4’-methyl acetylfentanyl and its isomer fentanyl. Acetylfentanyl has a close match with its reference standard giving a high match score of 99.12. Despite fentanyl and 4’-methyl acetylfentanyl being isomers, they have different fragmentation patterns due to the differing location of a methyl group, resulting in a poor match score (25.12) of 4’-methyl acetylfentanyl relative to the fentanyl.