{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T14:39:58Z","timestamp":1786977598290,"version":"build-2736575974"},"reference-count":48,"publisher":"Wiley","issue":"11","license":[{"start":{"date-parts":[[2025,7,4]],"date-time":"2025-07-04T00:00:00Z","timestamp":1751587200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000190","name":"U.S. Department of Commerce","doi-asserted-by":"publisher","award":["60NANB23D092"],"award-info":[{"award-number":["60NANB23D092"]}],"id":[{"id":"10.13039\/100000190","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["analyticalsciencejournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Drug Testing and Analysis"],"published-print":{"date-parts":[[2025,11]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Nitazene analogs are potent novel synthetic opioids (NSOs) that are becoming increasingly common and pose a threat to the public because of their fentanyl\u2010like effects. Although 12 nitazene analogs are currently classified as Schedule I under the U.S. Controlled Substances Act, novel analogs continue to emerge, making their identification in forensic laboratories exceedingly difficult. Liquid chromatography\u2013electrospray ionization\u2013tandem mass spectrometry (LC\u2013ESI\u2013MS\/MS) is commonly utilized in toxicology laboratories and is becoming more common for seized drug analysis, particularly for compounds less suited for gas chromatography\u2013electron ionization\u2013mass spectrometry (GC\u2013EI\u2013MS). This study provides a comprehensive structural characterization of 38 representative nitazene analogs using LC\u2013ESI\u2013MS\/MS instrumentation, including the proposed fragmentation mechanisms that lead to the formation of diagnostic product ions, enabling analog differentiation. General fragmentation pathways and mechanisms are proposed for all nitazene analogs, including inductive cleavages and molecular rearrangements. Overall, the most common product ions for nitazene analogs are derived from the substitutions to the amine or benzyl moieties, such as\n                    <jats:italic>m\/z<\/jats:italic>\n                    100,\n                    <jats:italic>m\/z<\/jats:italic>\n                    72,\n                    <jats:italic>m\/z<\/jats:italic>\n                    44, and\n                    <jats:italic>m\/z<\/jats:italic>\n                    107. However, the presence of different substitutions shifts the observed product ions. For example, recently occurring piperidine or pyrrolidine rings produce diagnostic product ions at\n                    <jats:italic>m\/z<\/jats:italic>\n                    112 and\n                    <jats:italic>m\/z<\/jats:italic>\n                    98, respectively. Therefore, modification to the core nitazene structure produces different diagnostic product ions, which can be used to identify existing and novel analogs. This study provides a comprehensive assessment of the fragmentation behavior of nitazene analogs under ESI\u2013MS\/MS conditions, which provides the basis for identifying new structural modifications in novel nitazene analogs.\n                  <\/jats:p>","DOI":"10.1002\/dta.3921","type":"journal-article","created":{"date-parts":[[2025,7,4]],"date-time":"2025-07-04T04:30:55Z","timestamp":1751603455000},"page":"2127-2140","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Structural Characterization of Nitazene Analogs Using Electrospray Ionization\u2013Tandem Mass Spectrometry (ESI\u2013MS\/MS)"],"prefix":"10.1002","volume":"17","author":[{"given":"Emma\u00a0K.","family":"Hardwick","sequence":"first","affiliation":[{"name":"Department of Forensic Science Sam Houston State University  Huntsville Texas USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9932-8273","authenticated-orcid":false,"given":"J.\u00a0Tyler","family":"Davidson","sequence":"additional","affiliation":[{"name":"Department of Forensic Science Sam Houston State University  Huntsville Texas USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,7,4]]},"reference":[{"key":"e_1_2_9_2_1","unstructured":"UNODC \u201cWorld Drug Report 2024 \u201d United Nations Office on Drugs and Crime (2024)."},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.forsciint.2023.111775"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/S2215\u20100366(19)30218\u20104"},{"key":"e_1_2_9_5_1","first-page":"5188","volume-title":"Schedules of Controlled Substances: Temporary Placement of Fentanyl\u2010Related Substances in Schedule I","year":"2018"},{"key":"e_1_2_9_6_1","unstructured":"\u201cH.R.10545 \u2010 American Relief Act 2025. 118th Congress.\u201d"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.3390\/biology12020273"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/dta.2738"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.7759\/cureus.40736"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/dta.3113"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1093\/jat\/bkaa016"},{"key":"e_1_2_9_12_1","unstructured":"A. J.Krotulski S. E.Walton J. S.DeBord A. L. AMohr andB. K.Logan \u201cNPS Opioids in the United States Q4 2024 \u201d (2024)."},{"key":"e_1_2_9_13_1","doi-asserted-by":"publisher","DOI":"10.1007\/s11419\u2010020\u201000552\u20109"},{"key":"e_1_2_9_14_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00204\u2010022\u201003276\u20104"},{"key":"e_1_2_9_15_1","doi-asserted-by":"publisher","DOI":"10.1021\/acschemneuro.1c00064"},{"key":"e_1_2_9_16_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00204\u2010022\u201003294\u20102"},{"key":"e_1_2_9_17_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00204\u2010024\u201003774\u20107"},{"key":"e_1_2_9_18_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00213\u2010023\u201006451\u20102"},{"key":"e_1_2_9_19_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00213\u2010022\u201006292\u20105"},{"key":"e_1_2_9_20_1","first-page":"60761","volume-title":"Schedules of Controlled Substances: Placement of Isotonitazene in Schedule I","year":"2021"},{"key":"e_1_2_9_21_1","first-page":"21556","volume-title":"Schedules of Controlled Substances: Temporary Placement of Butonitazene, Etodesnitazene, Flunitazene, Metodesnitazene, Metonitazene, N\u2010Pyrrolidino etonitazene, and Protonitazene in Schedule I","year":"2022"},{"key":"e_1_2_9_22_1","first-page":"60817","volume-title":"Schedules of Controlled Substances: Temporary Placement of N\u2010Desethyl Isotonitazene and N\u2010Piperidinyl Etonitazene in Schedule I","year":"2024"},{"key":"e_1_2_9_23_1","volume-title":"Toxicological Time Travel: Retrospective Datamining of Analytical Time\u2010Of\u2010Flight Mass Spectrometry (TOFMS) Data for Evaluating the Rise and Fall of Novel Opioid and Fentanyl Analog Use in the United States","author":"Mohr A. 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