Validation of an analytical method for quantitation of metonitazene and isotonitazene in plasma, blood, urine, liver and brain and application to authentic postmortem casework in New York City
Abstract
Starting in 2019, an emerging class of novel opioids causing public health concern was benzimidazole opioids, also known as “nitazenes.” Two nitazenes, isotonitazene and metonitazene, were detected in postmortem samples received at the New York City Office of Chief Medical Examiner. A protein precipitation extraction procedure was developed and validated for metonitazene and isotonitazene using 50 μL of blood, serum, liver, brain and urine utilizing liquid chromatography–tandem mass spectrometry. The limit of detection for both analytes was 0.10 ng/mL in plasma, blood and brain and 1.0 ng/mL for urine and liver. The developed method was applied to authentic casework in which isotonitazene was detected in 10 cases between 2021 and 2022, with femoral blood concentrations ranging from 0.11 to 12 ng/mL. Metonitazene was detected in four cases in 2022, with concentrations ranging from 0.10 to 1.5 ng/mL in femoral blood. All but one case had the presence of fentanyl and/or fentanyl analogs, and the next most commonly encountered analyte in these cases was xylazine. The manner of death was accidental for all cases with a detected nitazene, and all but one case was attributed to mixed drug intoxications. None of the cases reported the identified nitazene compound as the sole intoxicant responsible for death. The opioid crisis continues to tear apart communities throughout the world, including New York City. Continued research and communication regarding these drugs helps to fight this crisis.
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Forensic laboratories are adapting to analyse nitazenes in alternative matrices such as hair for retrospective exposure assessment, dried blood spots for micro-sampling in clinical settings, and wastewater for early warning and epidemiological monitoring.
“Forensic laboratories are also adapting to analyse nitazenes in alternative matrices such as hair [62] for retrospective exposure assessment, dried blood spots [54,63] for micro-sampling in clinical settings, and wastewater for early warning and epidemiological monitoring [50,64].”
From Nitazenes: The Emergence of a Potent Synthetic Opioid Threat (2025) · cites this paper as [63]
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“Forensic laboratories are also adapting to analyse nitazenes in alternative matrices such as hair [62] for retrospective exposure assessment, dried blood spots [54,63] for micro-sampling in clinical settings, and wastewater for early warning and epidemiological monitoring [50,64].”
Testing for Protonitazene in Human Hair Using LC–MS-MS
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A novel screening workflow for nitazene analogs using LC–MS/MS precursor ion scan acquisition
Pacana, A. L., & Skillman, B. N. (2025) · Journal of Analytical Toxicology · doi:10.1093/jat/bkaf046 · Cited by 8 · see citing works
Tomiyama, K.-I., & Funada, M. (2025) · Toxicology and Applied Pharmacology · doi:10.1016/j.taap.2025.117361 · Cited by 4 · see citing works
- Authors
- Pardi, J., Ford, S., & Cooper, G.
- Affiliations
- St. John's University (US)
- Office of Chief Medical Examiner (US)
- Corresponding author
- Pardi, Justine
- Venue
- Journal of Analytical Toxicology
- Publisher
- Oxford University Press (OUP)
- Published
- 2023-08-28
- Volume
- 47
- Issue
- 8
- Pages
- 648-655
- ISSN
- 0146-4760 (ISSN-L)
- 1945-2403
- OpenAlex
- W4386209819
- Cited by
- 29
- References
- 3
- Citations by year
- 2026: 10 · 2025: 13 · 2024: 6
- FWCI
- 5.16
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Analytical Toxicology (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Forensic Toxicology and Drug Analysis
- Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Opioid Use Disorder Treatment
- Physical Sciences › Chemistry › Analytical Chemistry › Analytical Methods in Pharmaceuticals
- Keywords
- isotonitazene, nitazenes, postmortem toxicology, fentanyl, xylazine, accidental death, opioid epidemic, method validation
- MeSH terms
- Amines, Analgesics, Opioid, Benzimidazoles, Brain, Fentanyl, Humans, Liver, New York City, Plasma, Tandem Mass Spectrometry
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