Structural modification of fentanyls for their retrospective identification by gas chromatographic analysis using chloroformate chemistry

Abstract

The one-step breakdown and derivatization of a panel of nine fentanyls to yield uniquely tagged products that can be detected by Electron Ionization Gas Chromatography-Mass Spectrometry (EI-GC-MS) is presented. The method involves the treatment of the synthetic opioids with 2,2,2-trichloroethoxycarbonyl chloride (TrocCl) at 60 °C for 3 h 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’s LLOD was determined to be 10 ng/mL while its LLOQ was found to be 20 ng/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–MS analysis.

Analysis, identification and confirmation of synthetic opioids using chloroformate chemistry: Retrospective detection of fentanyl and acetylfentanyl in urine and plasma samples by EI-GC-MS and HR-LC-MS

“…Another factor is the inability to derivatize fentanyls using traditional derivatizing agents for converting them into species that can be detected by GC-MS. Intrigued by the challenges posed by fentanyl's chemical inertness, we explored the use of chloroformate chemistry to investigate its potential for modifying this opioid. To this end, we found that reaction between fentanyls and Troc-Cl yields two unique and predictable products bearing structural features from the original fentanyl [32]. In our original report, we demonstrated the extent of this reaction using only DCM as the organic medium.…”

“…Upon careful analysis it becomes evident that this complex spectrum belongs to more than one species, one of which is the desired Troc-norfentanyl (Fig 4A). Key ions found in this spectrum that arise from Troc-norfentanyl include its base peak m/z = 149 and the almost equally intense and diagnostic m/z = 150 peak [32]. However, it is only these large ion peaks that can be gleaned a priori by studying the spectrum in Fig 4A while an interesting observation can be made in the area where the molecular ion peak for Troc-norfentanyl should appear (m/z = 406).…”

“…The reaction between fentanyl and more complex members of this family of synthetic opioids resulted in the formation of two products, that aside from being easily identified by EI-GC-MS, can be pieced together to retrospectively identify the original fentanyl (Fig 2A). We demonstrated that the method worked efficiently in a panel of ten representative fentanyls showing its broad-spectrum quality with LLOD and LLOQ values of 10 and 20 ng/mL respectively for fentanyl [32]. Interestingly, reaction of norfentanyl with Troc-Cl affords the same product that forms from the reaction of fentanyl itself with the chloroformate.…”

“…Recently, our laboratory introduced a method for the indirect analysis of fentanyl and analogs based on their chemical modification with 2,2,2-trichloroethoxycarbonyl chloride (Troc-Cl) [32]. The reaction between fentanyl and more complex members of this family of synthetic opioids resulted in the formation of two products, that aside from being easily identified by EI-GC-MS, can be pieced together to retrospectively identify the original fentanyl (Fig 2A).…”

Evaluation of polyanionic cyclodextrins as high affinity binding scaffolds for fentanyl

“…N -methyl-2-pyrrolidone was purchased from Applied Biosystems, Thermo Fisher (Grand Island, NY). 4-Mercaptobutan-1-ol and 3-mercaptopropan-1-ol were synthesized as previously described 45 , 46 purified by flash column chromatography in silica gel cartridges with a Biotage Isolera purification system, and their purity assessed by 1 H NMR and GC-MS 47 – 49 . Deuterated water (D 2 O) was purchased from Cambridge Isotope Laboratories, Inc. (Tewksbury, MA).…”