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The method involves the treatment of the synthetic opioids with 2,2,2-trichloroethoxycarbonyl chloride (TrocCl) at 60\u00a0\u00b0C for 3\u00a0h in dichloromethane and furnishes two products from one fentanyl molecule that can be used to retrospectively identify the original opioid. Parameters that were studied and fully optimized for the method included temperature, solvent, nature of scavenging base and reaction time. One of the two resulting products from the reaction bears the trichloroethoxycarbonyl (Troc) tag attached to the norfentanyl portion of the original opioid and greatly aids in the opioid detection and identification process. The methodology has been applied to the chemical modification of a panel of nine fentanyls and in all cases the molecular ion peak for the Troc-norfentanyl product bearing the distinctive trichloroethyl isotopic signature can be clearly observed. The method\u2019s LLOD was determined to be 10\u00a0ng\/mL while its LLOQ was found to be 20\u00a0ng\/mL. This methodology represents the first application of chloroformates in the chemical modification of this class of synthetic opioids that are notoriously inert to common derivatization strategies available for GC\u2013MS analysis.<\/jats:p>","DOI":"10.1038\/s41598-021-01896-x","type":"journal-article","created":{"date-parts":[[2021,11,18]],"date-time":"2021-11-18T11:06:20Z","timestamp":1637233580000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Structural modification of fentanyls for their retrospective identification by gas chromatographic analysis using chloroformate chemistry"],"prefix":"10.1038","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8641-9077","authenticated-orcid":false,"given":"Carlos A.","family":"Valdez","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2209-0185","authenticated-orcid":false,"given":"Roald N.","family":"Leif","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6703-8079","authenticated-orcid":false,"given":"Robert D.","family":"Sanner","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Todd H.","family":"Corzett","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8691-9063","authenticated-orcid":false,"given":"Mark L.","family":"Dreyer","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Katelyn E.","family":"Mason","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2021,11,18]]},"reference":[{"key":"1896_CR1","doi-asserted-by":"publisher","first-page":"31","DOI":"10.1021\/jm50010a003","volume":"2","author":"PAJ Janssen","year":"1960","unstructured":"Janssen, P. 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