Identification and characterization of the new designer drug 4′-methylethcathinone (4-MEC) and elaboration of a novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) screening method for seven different methcathinone analogs

doi:10.1016/j.forsciint.2011.03.019

Forensic Science International

Volume 210, Issues 1–3, 15 July 2011, Pages 213-220

https://doi.org/10.1016/j.forsciint.2011.03.019 Get rights and content

Abstract

A fast and simple LC–MS/MS method was developed for screening mephedrone, butylone, methylenedioxypyrovalerone (MDPV), flephedrone, methylone and methedrone in bulk powder samples. Samples were separated on a reverse phase column using gradient elution with mixtures of water, acetonitrile and formic acid. After optimization a limit of detection of about 2 ng mL⁻¹ was achieved using multiple reaction monitoring (MRM) mode. Total run time was less than 8 min. Typical fragmentation characteristics of the studied compounds are discussed. The method was successfully applied to several unknown bulk powder samples seized by the Hungarian Customs and Finance Guard. One of the samples contained the new designer drug 4′-methylethcathinone (4-MEC), which was identified and characterized by LC–MS/MS, NMR, FT-IR and LC–TOF-MS techniques. The method is also deemed to be applicable for the screening of simple dosage forms such as tablets and capsules.

Introduction

The National Institute of Pharmacy (NIP) functions as the drug control agency of human medicinal products in Hungary and in terms of the national legislation it is responsible for providing expert reports on seized samples presumed to contain active pharmaceutical ingredients. In practice, such suspect “drug-like” samples often turn out to contain illegal compounds such as psychoactive substances or doping agents.

In 2010 the laboratory of the NIP was requested to give expert reports on several unknown bulk powder samples seized by the Hungarian Customs and Finance Guard. Package information and invoices claimed that the samples were pharmaceutical excipients or similar harmless substances. However, analysis of the samples demonstrated that each powder contained the hydrochloride salt of one of the following compounds: mephedrone (4′-methylmethcathinone) (1), butylone (beta-keto-MBDB) (2), 3,4-methylenedioxypyrovalerone (MDPV) (3), flephedrone (4′-fluoromethcathinone) (4) and a new potential designer drug, 4′-methylethcathinone (4-MEC) (7) (Fig. 1). All substances are chemical derivatives of the psychoactive stimulant methcathinone.

Among others, some of these compounds were mentioned in a 2010 joint report of Europol and the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) on mephedrone [1]. The report concluded that in many countries mephedrone was marketed as a legal alternative to ecstasy or cocaine. Participants reported seizures of mephedrone in the form of bulk powder or tablets and provided evidence of toxicity associated with mephedrone use. The conclusion of the study was confirmed by other works reporting undesired side-effects, symptoms of intoxication as well as fatalities associated with mephedrone abuse [2], [3], [4], [5], [6], [7].

As a result, mephedrone has been illegalized by several European countries (including Hungary) recently. Furthermore, the United Kingdom decided to put a generic ban on the entire mephedrone family based on the similarity of their chemical structures [2].

It was assumed that a method of appropriate sensitivity and selectivity for simultaneous detection of methcathinone derivatives in pharmaceutical formulations like mixed or triturated powders and tablets could considerably help control laboratories to provide expert reports within the usually very strict timelines. After a search in the literature it was found that despite the numerous scientific publications on the analysis of this group of substances none of the studies addressed this particular issue.

Detailed structure elucidation of mephedrone by NMR, MS, IR and molecular modeling was carried out by several research groups [8], [9]. Flephedrone [10], methylone and butylone [9], MDPV [11], [12] as well as other structurally related 4′-methoxymethcathinone and pyrrolidine derivatives [13], [14], [15] were also characterized. Quantification and metabolization studies in biological matrices were published for mephedrone [4], [6], [16], methedrone [17], methylone [16], [18], [19], MDPV [20], [21] and butylone [16], [22].

The present paper describes a rapid and simple target screening method by LC–MS/MS for the detection and identification of seven methcathinone derivatives in bulk powders. The target group includes five compounds identified by the laboratory of the NIP in seized samples (compounds 1–4 and 7) as well as two other frequently encountered structures [17], [23], [24]: methylone and methedrone (compounds 5 and 6 in Fig. 1). Possible applicability of the method for more complex matrices is discussed. Since no reports were found concerning characterization of 4-MEC, structure elucidation of this compound by LC–MS/MS, NMR, FT-IR and high resolution MS (HRMS) was also carried out and the results are presented.

Section snippets

Materials

Certified reference standards of compounds 5 and 6 were purchased from LGC Standards (Teddington, United Kingdom) in the form of hydrochloride salts. Because compounds 1–4 derived from seized samples their identity and purity were confirmed by LC–MS/MS, NMR, FT-IR and HRMS techniques.

Solvents and reagents

Water was produced by a Millipore Elix3 (Billerica, MA, USA) water purifying system. Acetonitrile (ACN), methanol (MeOH) (both from Merck KGaA, Darmstadt, Germany) and formic acid (Sigma–Aldrich GmbH, Seelze,

Fragmentation studies and LC–MS/MS screening method for compounds 1–6

Although fragmentation studies of the analytes have already been published it is believed that a comparison of their fragmentation characteristics may help to identify other methcathinone derivatives which are unknown for the time being but may be reported as designer drugs in the future. Full scan mass spectra were obtained using ESI positive mode. Electrospray ionization gave better responses for the compounds under investigation compared to atmospheric pressure chemical ionization (APCI).

Conclusions

The method described in this paper was developed using a very pragmatic approach primarily considering the problems usually encountered in the laboratories of forensic or drug control agencies. For the purpose of this paper, the term “screening method” was used for an analytical procedure developed in order to provide a preferably simple and fast method for the detection of certain target molecules or groups of target molecules (in this case methcathinones). The method was successfully applied

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Identification and characterization of the new designer drug 4′-methylethcathinone (4-MEC) and elaboration of a novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) screening method for seven different methcathinone analogs

Abstract

Introduction

Section snippets

Materials

Solvents and reagents

Fragmentation studies and LC–MS/MS screening method for compounds 1–6

Conclusions

Lancet

Forensic Sci. Int.

Bioorg. Med. Chem. Lett.

Forensic Sci. Int.

Forensic Sci. Int.

Forensic Sci. Int.

J. Chromatogr. B.

Forensic Sci. Int.

Prog. Neuropsychopharmacol. Biol. Psychiatry

A Joint Report on a New Psychoactive Substance: 4-Methylmethcathinone (Mephedrone)

Mephedrone use and associated adverse effects in school and college/university students before the UK legislation change

QJM

Recreational use of mephedrone (4-methylmethcathinone, 4-MMC) with associated sympathomimetic toxicity

J. Med. Toxicol.

Multiple-drug toxicity caused by the coadministration of 4-methylmethcathinone (mephedrone) and heroin

J. Anal. Toxicol.