Carfentanil structural analogs found in street drugs by paper spray mass spectrometry and their characterization by high-resolution mass spectrometry

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Borden, Scott A.
Mercer, Savannah R.
Saatchi, Armin
Wong, Ernest
Stefan, Cristiana M.
Wiebe, Heather
Hore, Dennis K.
Wallace, Bruce
Gill, Chris G.
Carfentanil is one of the most potent synthetic opioids ever developed, with an estimated analgesic potency approximately 20–100 times that of fentanyl and 10,000 times that of morphine. Carfentanil has been appearing in the illicit drug supply in many regions and has been linked to fatal overdose events. A subset of 59 street drug samples obtained in Victoria, B.C., that were confirmed to contain carfentanil were analyzed by mass spectrometry for this study. Carfentanil quantitation by paper spray mass spectrometry ranged from 0.05 to 2.95 w/w% (median = 0.32%) in the original drug sample. Paper spray mass spectrometry analysis also detected two unknown peaks at m/z 380.2 and 381.2 in 31 of these 59 samples (53%). Initial tandem mass spectrometry experiments revealed structural similarities between these unknown compounds and carfentanil, suggesting they were potential structural analogs, possibly arising from incomplete purification during synthesis. High-resolution mass spectrometry determined the chemical formulas of these compounds as C23H29N3O2 (m/z 380.2333) and C23H29N2O3 (m/z 381.2137). Literature and tandem mass spectrometry results were used to determine the identity of these potential new psychoactive substances, C23H29N3O2 as desmethylcarfentanil amide and C23H29N2O3 as desmethylcarfentanil acid. μ-Opioid receptor binding modeling determined that the binding poses of these analogs were nearly identical to that of carfentanil with relative binding energy calculations of 0.544 kJ/mol (desmethylcarfentanil amide) and −0.171 kJ/mol (desmethylcarfentanil acid); these data suggest they may share the toxic effects of carfentanil and have similar potencies.
This is the peer reviewed version of the following article: Borden, S.A., Mercer, S.R., Saatchi, A., Wong, E., Stefan, C.M., Wiebe, H., Hore, D.K., Wallace, B., & Gill, C.G. (2023). Carfentanil structural analogs found in street drugs by paper spray mass spectrometry and their characterization by high-resolution mass spectrometry. Drug Testing and Analysis, 15(5), 484-494, which has been published in final form at This article maybe used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
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