LC‐MS/MS in the elucidation of an isomer of the recreational drug methylenedioxy ethylamphetamine: Methylenedioxy dimethylamphetamine

Abstract

This paper describes the surplus value of a quadrupole-orthogonal acceleration TOF mass spectrometer, coupled to a liquid chromatographic separation system, for the unequivocal identification and structural elucidation of an unknown compound in the field of designer drugs. In a patient sample set (blood, tissues, vitreous humor, etc.), analyzed with a dedicated liquid chromatographic-fluorescence detection method for the determination of methylenedioxy amphetamine, methylenedioxy methamphetamine, and methylenedioxy ethylamphetamine (MDEA), a "strange" inexplicable peak appeared at a retention time not corresponding to any of our reference materials. Based on the identical excitation and emission wavelengths in detection, and a retention behavior comparable to MDEA, it was assumed that this unknown compound was an isomer of the recreational drug MDEA. With a simple and straightforward methodological crossover between LC fluorescence detection and LC-MS/MS, additional information for structural elucidation was easily obtained. Chromatographic separation was achieved on a Hypersil BDS C18 column (fluorescence detection part) and on a Hypersil BDS phenyl column (mass spectrometric detection part). MS showed that the unknown compound's molecular mass was identical to that of MDEA, and, in addition, its fragmentation pattern too proved quite similar to that of MDEA. A thorough literature overview and study of the fragmentation pattern by means of the MS/MS spectrum led to an evidence-based hypothesis of 3,4-methylenedioxy N,N-dimethylamphetamine (MDDM) being the unknown compound. To confirm this hypothesis, MDDM was synthesized and its presence in our biological sample was finally demonstrated by co-injection with alternatively synthesized MDDM and MDEA. This application shows the synergism between LC and MS in the elucidation of unknown compounds, nevertheless emphasizing the essence of chromatographic separation when dealing with isomers.

Differentiation of structural isomers in a target drug database by LC/Q‐TOFMS using fragmentation prediction

“…[33] Tramadol and O-desmethyl venlafaxin sharing a molecular formula of C 16 H 25 NO 2 and [M+H] + 264.1958, have been reported to undergo similar fragmentation, [34] yielding only a single fragment of m/z 58. Similar results have been reported about isomers that could not be distinguished based on their fragments, including the compounds studied in the present work (MDEA and MDDMA, [35] and ephedrine and pseudoephedrine [36] ). Similar results have been reported about isomers that could not be distinguished based on their fragments, including the compounds studied in the present work (MDEA and MDDMA, [35] and ephedrine and pseudoephedrine [36] ).…”

Postmortem distribution of 3,4-methylenedioxy-N,N-dimethyl-amphetamine (MDDM or MDDA) in a fatal MDMA overdose

“…Coinjection of the pure (in-house synthesized) MDDM together with a blood extract unequivocally identified the unknown compound as MDDM [8]. Calibrators containing increasing amounts of MDDM in various matrices were made.…”

“…The unknown substance was detected when screening some extracts (blood, urine, or tissue) for the presence of amphetamine and methylenedioxyamphetamine designer drugs, applying a previously described LC-MS/MS method [7]. Thorough investigation of the literature and of the obtained MS/MS spectrum (precursor and product ions) revealed that the initially unidentified molecule was MDDM [8]. Due to the presence of a 1,000-fold higher amount of MDMA and to the lack of selectivity, other techniques, such as HPLC-diode array detection (HPLC-DAD) and GC-MS, had failed to demonstrate the presence of the unknown designer drug.…”

“…The 3,4-methylenedioxymethylpropylamphetamine (MDMPA) was synthesized in-house [7] and was used as an internal standard. The MDDM standard was also synthesized in-house [8]. Stock solutions of these compounds (1.0 mg/ml) were prepared in methanol, stored at −20°C, and were stable for at least 1 year.…”

“…Recently, the performed procedure was reported in detail [8]. Extraction was based on liquid-liquid extraction under alkaline conditions [7], followed by a gradient-based LC-MS analysis on a Hypersil Base Deactivated Silica (BDS) phenyl column [8].…”