{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T23:24:34Z","timestamp":1787009074977,"version":"build-2736575974"},"reference-count":16,"publisher":"Oxford University Press (OUP)","issue":"9","license":[{"start":{"date-parts":[[2025,6,4]],"date-time":"2025-06-04T00:00:00Z","timestamp":1748995200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,11,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The purpose of this study was to develop and validate an analytical method to chromatographically separate, identify, and quantify ortho-methylfentanyl (o-methylfentanyl) in postmortem blood. A combination of simple protein precipitation with liquid chromatography\u2013tandem mass spectrometry (LC\u2013MS\/MS) was utilized to facilitate chromatographic separation of similar fentanyl analogs, including both meta (m-) and para (p-) methylfentanyl. The analytical range was 1 to 200\u2009ng\/mL; the method was validated in accordance with ANSI\/ASB Standard 036. In addition to providing details of the validated analytical method, this study details the results of the analysis of 112 case samples (101 postmortem case samples and 11 antemortem case samples) from drug-toxicity related death investigations completed by the toxicology laboratory of the Office of the Chief Medical Examiner, Edmonton, Alberta, Canada. Analytical data is presented which compares concentrations of ortho-methylfentanyl in paired postmortem blood collected from both a visualized, ligated femoral vein together with postmortem blood collected directly from the heart, that is, visualized. Median blood ortho-methylfentanyl concentrations were found to be 5.94\u2009ng\/mL (femoral) and 8.04\u2009ng\/mL (cardiac). The median cardiac-to-femoral blood concentration ratio across the entire data set was 1.19. The study highlights the varied distribution in the body based on the median concentration of these drugs in postmortem blood.<\/jats:p>","DOI":"10.1093\/jat\/bkaf050","type":"journal-article","created":{"date-parts":[[2025,6,3]],"date-time":"2025-06-03T07:31:39Z","timestamp":1748935899000},"page":"637-644","source":"Crossref","is-referenced-by-count":3,"title":["LC\u2013MS\/MS determination of the novel fentanyl analog, ortho-methylfentanyl, in drug-related toxicity casework: concentrations in ligated femoral blood"],"prefix":"10.1093","volume":"49","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5157-0826","authenticated-orcid":false,"given":"Craig N","family":"Chatterton","sequence":"first","affiliation":[{"name":"Office of the Chief Medical Examiner , Edmonton, Alberta, T6H 5R8,","place":["Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Russell P","family":"Handy","sequence":"additional","affiliation":[{"name":"Office of the Chief Medical Examiner , Edmonton, Alberta, T6H 5R8,","place":["Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Glen K","family":"Shoemaker","sequence":"additional","affiliation":[{"name":"Office of the Chief Medical Examiner , Edmonton, Alberta, T6H 5R8,","place":["Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2025,6,4]]},"reference":[{"key":"2026012714122847800_bkaf050-B1","author":"Government of Canada","year":"2024"},{"key":"2026012714122847800_bkaf050-B2","doi-asserted-by":"crossref","first-page":"1156","DOI":"10.2174\/1570159X15666170504095823","article-title":"Opioids and the blood-brain barrier: A dynamic interaction with consequences on drug disposition in brain","volume":"15","author":"Chaves","year":"2017","journal-title":"Curr Neuropharmacol"},{"key":"2026012714122847800_bkaf050-B3","doi-asserted-by":"publisher","first-page":"32","DOI":"10.1186\/s12987-017-0080-3","article-title":"The opioid epidemic: a central role for the blood brain barrier in opioid analgesia and abuse","volume":"14","author":"Schaefer","year":"2017","journal-title":"Fluids Barriers CNS"},{"key":"2026012714122847800_bkaf050-B4","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1007\/978-1-0716-2605-4_4","volume-title":"Methods for Novel Psychoactive Substance Analysis","author":"Rodda","year":"2023"},{"key":"2026012714122847800_bkaf050-B5","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/j.neuropharm.2017.08.016","article-title":"Pharmacological characterization of novel synthetic opioids (NSO) found in the recreational drug marketplace","volume":"134","author":"Baumann","year":"2018","journal-title":"Neuropharmacology"},{"key":"2026012714122847800_bkaf050-B6","author":"United Nations Office on Drugs and Crime","year":"2022"},{"key":"2026012714122847800_bkaf050-B7","doi-asserted-by":"crossref","first-page":"1212","DOI":"10.1002\/dta.2822","article-title":"In vitro pharmacology of fentanyl analogs at the human mu opioid receptor and their spectroscopic analysis","volume":"12","author":"Hassanien","year":"2020","journal-title":"Drug Test Anal"},{"key":"2026012714122847800_bkaf050-B8","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s11419-007-0039-1","article-title":"Studies on 1-(2-phenethyl)-4-(N-propionylanilino) piperidine (fentanyl) and its related compounds. 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Structure-analgesic activity relationship for fentanyl, methyl-substituted fentanyls and other analogues","volume":"26","author":"Higashikawa","year":"2008","journal-title":"Forensic Toxicol"},{"key":"2026012714122847800_bkaf050-B9","volume-title":"Adulterants, Contaminants and co-Occurring Substances in Drugs on the Illegal Market in Canada: An Analysis of Data from Drug Seizures, Drug Checking and Urine Toxicology.","author":"Payer","year":"2020"},{"key":"2026012714122847800_bkaf050-B10","author":"American Academy of Forensic Sciences (AAFS) Standard Board (ASB)","year":"2019"},{"key":"2026012714122847800_bkaf050-B11","doi-asserted-by":"crossref","first-page":"146","DOI":"10.1016\/j.forsciint.2017.12.031","article-title":"The distribution and redistribution of fentanyl & norfentanyl in post mortem samples","volume":"284","author":"Chatterton","year":"2018","journal-title":"Forensic Sci Int"},{"key":"2026012714122847800_bkaf050-B12","doi-asserted-by":"crossref","first-page":"111777","DOI":"10.1016\/j.forsciint.2023.111777","article-title":"Fentanyl concentrations in ligated femoral blood in the presence and absence of NPS benzodiazepine drugs. A review of over 1250 benzo-dope\/fentanyl toxicity cases in Alberta, Canada","volume":"350","author":"Chatterton","year":"2023","journal-title":"Forensic Sci Int"},{"key":"2026012714122847800_bkaf050-B13","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1093\/jat\/bkac014","article-title":"Toxicological analysis of fluorofentanyl isomers in postmortem blood","volume":"46","author":"Truver","year":"2022","journal-title":"J Anal Toxicol"},{"key":"2026012714122847800_bkaf050-B14","doi-asserted-by":"crossref","first-page":"1358","DOI":"10.1002\/dta.2393","article-title":"Analysis of fentanyl analogs and novel synthetic opioids in blood, serum\/plasma, and urine in forensic casework","volume":"10","author":"Moody","year":"2018","journal-title":"Drug Test Anal"},{"key":"2026012714122847800_bkaf050-B15","doi-asserted-by":"crossref","first-page":"573","DOI":"10.1093\/jat\/bkae062","article-title":"Fluorofentanyl and novel synthetic opioids in accidental overdose deaths","volume":"48","author":"Yu","year":"2024","journal-title":"J Anal Toxicol"},{"key":"2026012714122847800_bkaf050-B16","article-title":"Anderson DT. 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