{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T16:55:38Z","timestamp":1791824138837,"version":"4.3.4"},"reference-count":24,"publisher":"Oxford University Press (OUP)","issue":"3","license":[{"start":{"date-parts":[[2021,11,18]],"date-time":"2021-11-18T00:00:00Z","timestamp":1637193600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100005289","name":"National Institute of Justice","doi-asserted-by":"publisher","award":["2020-DQ-BX-0007"],"award-info":[{"award-number":["2020-DQ-BX-0007"]}],"id":[{"id":"10.13039\/100005289","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,3,21]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>Novel psychoactive substances (NPS) continue to represent a threat to public health and safety. The number of new drugs in the latest emergent synthetic opioid class\u2014the 2-benzylbenzimidazole analogs\u2014also called the nitazenes\u2014has begun to dominate the current new synthetic opioid (NSO) subclass of NPS. We describe a liquid chromatography\u2013tandem quadrupole mass spectrometry method for the quantification of nine analogs and\/or metabolites of drugs in this series: isotonitazene, metonitazene, protonitazene, etonitazene, clonitazene, flunitazene, N-desethyl isotonitazene, 5-amino isotonitazene and 4\u02b9-hydroxy nitazene in human whole blood, urine, and tissue. Samples were prepared for analysis using a basic liquid\u2013liquid extraction. Chromatographic separation was achieved using a C-18 analytical column. Multiple reaction monitoring mode was used for detection. The calibration range for the analytes was 0.5\u201350\u2009ng\/mL (except for 5-amino isotonitazene, which was 1.0\u201350\u2009ng\/mL). The limit of detection was 0.1\u2009ng\/mL, and the limit of quantitation was 0.5\u2009ng\/mL. The method had no carryover or interferences. Ionization enhancement was observed but did not affect quantitation. All analytes passed the method validation assessment. Authentic human samples suspected of containing NSOs were obtained from a medical examiner and coroner offices, as well as partnering forensic toxicology laboratories. Isotonitazene was confirmed in 92 blood samples, and its metabolites were confirmed across various matrices. Metonitazene (n\u2009=\u200935), flunitazene (n\u2009=\u20095), protonitazene (n\u2009=\u20093), etodesnitazene (n\u2009=\u20092) and butonitazene (n\u2009=\u20091) were also detected in cases. These newly emerging 2-benzylbenzimidazole analogs were commonly found in combination with NPS benzodiazepines and opioids (e.g., flualprazolam, fentanyl). Nitazene analogs are potent esoteric drugs that may not be identified during routine toxicological screening, and specialized assays based on sensitive instrumentation are needed to accurately characterize these NSOs.<\/jats:p>","DOI":"10.1093\/jat\/bkab117","type":"journal-article","created":{"date-parts":[[2021,11,17]],"date-time":"2021-11-17T12:08:42Z","timestamp":1637150922000},"page":"221-231","source":"Crossref","is-referenced-by-count":91,"title":["A Forward-Thinking Approach to Addressing the New Synthetic Opioid 2-Benzylbenzimidazole Nitazene Analogs by Liquid Chromatography\u2013Tandem Quadrupole Mass Spectrometry (LC\u2013QQQ-MS)"],"prefix":"10.1093","volume":"46","author":[{"given":"Sara E","family":"Walton","sequence":"first","affiliation":[{"name":"Center for Forensic Science Research and Education, Fredric Rieders Family Foundation, 2300 Stratford Avenue, Willow Grove, PA 19090, USA"},{"name":"Jefferson College of Life Sciences, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1775-1882","authenticated-orcid":false,"given":"Alex J","family":"Krotulski","sequence":"additional","affiliation":[{"name":"Center for Forensic Science Research and Education, Fredric Rieders Family Foundation, 2300 Stratford Avenue, Willow Grove, PA 19090, USA"},{"name":"Jefferson College of Life Sciences, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2400-4711","authenticated-orcid":false,"given":"Barry K","family":"Logan","sequence":"additional","affiliation":[{"name":"Center for Forensic Science Research and Education, Fredric Rieders Family Foundation, 2300 Stratford Avenue, Willow Grove, PA 19090, USA"},{"name":"Jefferson College of Life Sciences, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA"},{"name":"NMS Labs, 200 Welsh Road, Horsham, PA 19044, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2021,11,18]]},"reference":[{"key":"2022032114035636200_R1","article-title":"Drug Overdose. Drug Overdose Deaths","author":"CDC Injury Center","year":"2021"},{"key":"2022032114035636200_R2","doi-asserted-by":"crossref","first-page":"202","DOI":"10.15585\/mmwr.mm7006a4","article-title":"Trends and geographic patterns in drug and synthetic opioid overdose deaths\u2014United States, 2013\u20132019","volume":"70","author":"Mattson","year":"2021","journal-title":"MMWR Morbidity and Mortality Weekly Report"},{"key":"2022032114035636200_R3","article-title":"Public Alert Isotonitazene NPS Discovery","author":"Krotulski","year":"2019"},{"key":"2022032114035636200_R4","doi-asserted-by":"publisher","DOI":"10.1002\/dta.2738","article-title":"Report on a novel emerging class of highly potent benzimidazole NPS opioids: chemical and in vitro functional characterization of isotonitazene","volume":"12","author":"Blanckaert","year":"2019","journal-title":"Drug Testing and Analysis"},{"key":"2022032114035636200_R5","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1093\/jat\/bkaa016","article-title":"Isotonitazene quantitation and metabolite discovery in authentic forensic casework","volume":"44","author":"Krotulski","year":"2020","journal-title":"Journal of Analytical Toxicology"},{"key":"2022032114035636200_R6","article-title":"United States Patent Office - Benzimidazoles","author":"Hoffman","year":"1960"},{"key":"2022032114035636200_R7","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1007\/BF02161116","article-title":"Synthese basisch substituierter, analgetisch wirksamer Benzimidazol-Derivate","volume":"13","author":"Hunger","year":"1957","journal-title":"Experientia"},{"key":"2022032114035636200_R8","doi-asserted-by":"crossref","first-page":"1241","DOI":"10.1021\/acschemneuro.1c00064","article-title":"Synthesis, chemical characterization, and mu-opioid receptor activity assessment of the emerging group of nitazene new synthetic opioids","volume":"12","author":"Vandeputte","year":"2020","journal-title":"ACS Chemical Neuroscience"},{"key":"2022032114035636200_R9","article-title":"EMCDDA technical report on the new psychoactive substance N,N-diethyl-2-[[4-(1-methylethoxy)phenyl]methyl]-5-nitro-1H-benzimidazole-1-ethanamine (isotonitazene)"},{"key":"2022032114035636200_R10","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1093\/jat\/bkaa016","article-title":"Isotonitazene quantitation and metabolite discovery in authentic forensic casework","volume":"44","author":"Krotulski","year":"2020","journal-title":"Journal of Analytical Toxicology"},{"key":"2022032114035636200_R11","doi-asserted-by":"crossref","first-page":"664","DOI":"10.1111\/1556-4029.14623","article-title":"Brorphine\u2014investigation and quantitation of a new potent synthetic opioid in forensic toxicology casework using liquid chromatography-mass spectrometry","volume":"6","author":"Krotulski","year":"2021","journal-title":"Journal of Forensic Sciences"},{"key":"2022032114035636200_R12","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1093\/jat\/bkaa070","article-title":"Flualprazolam blood concentrations in 197 forensic investigation cases","volume":"45","author":"Papsun","year":"2020","journal-title":"Journal of Analytical Toxicology"},{"key":"2022032114035636200_R13","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1097\/ADM.0000000000000775","article-title":"Emerging characteristics of isotonitazene-involved overdose deaths: a case-control study","volume":"15","author":"Shover","year":"2021","journal-title":"Journal of Addiction Medicine"},{"key":"2022032114035636200_R14","article-title":"Isotonitazene Found in Growing Ohio Overdose Deaths","volume-title":"Woods at Parkside","author":"The Woods at Parkside","year":"2021"},{"key":"2022032114035636200_R15","article-title":"Temporary Placement of Isotonitazene in ScheduleI","author":"Drug Enforcement Administration","year":"2020"},{"key":"2022032114035636200_R16","volume-title":"Controlled Substances - 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