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Test purchase, synthesis, and characterization of 2‐methoxydiphenidine (MXP) and differentiation from its meta ‐ and para ‐substituted isomers
Author(s) -
McLaughlin Gavin,
Morris Noreen,
Kavanagh Pierce V.,
Power John D.,
O'Brien John,
Talbot Brian,
Elliott Simon P.,
Wallach Jason,
Hoang Khoa,
Morris Hamilton,
Brandt Simon D.
Publication year - 2016
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.1800
Subject(s) - chemistry , orbitrap , mass spectrometry , high performance liquid chromatography , chromatography , protonation , structural isomer , analytical chemistry (journal) , stereochemistry , organic chemistry , ion
The structurally diverse nature of the 1,2‐diphenylethylamine template provides access to a range of substances for drug discovery work but some have attracted attention as ‘research chemicals’. The most recent examples include diphenidine, i.e. 1‐(1,2‐diphenylethyl)piperidine and 2‐methoxydiphenidine, i.e. 1‐[1‐(2‐methoxyphenyl)‐2‐phenylethyl]piperidine (MXP, methoxyphenidine, 2‐MXP) that have been associated with uncompetitive N ‐methyl‐D‐aspartate (NMDA) receptor antagonist activity. Analytical challenges encountered during chemical analysis include the presence of positional isomers. Three powdered samples suspected to contain 2‐MXP were obtained from three Internet retailers in the United Kingdom and subjected to analytical characterization by gas chromatography (GC) and high performance liquid chromatography (HPLC) coupled to various forms of mass spectrometry (MS). Nuclear magnetic resonance spectroscopy, infrared spectroscopy and thin layer chromatography were also employed. This was supported by the synthesis of all three isomers (2‐, 3‐ and 4‐MXP) by two different synthetic routes. The analytical data obtained for the three purchased samples were consistent with the synthesized 2‐MXP standard and the differentiation between the isomers was possible. Distinct stability differences were observed for all three isomers during in‐source collision‐induced dissociation of the protonated molecule when employing detection under HPLC selected‐ion monitoring detection, which added to the ability to differentiate between them. Furthermore, the analysis of a 2‐MXP tablet by matrix assisted inlet ionization Orbitrap mass spectrometry confirmed that it was possible to detect the protonated molecule of 2‐MXP directly from the tablet surface following addition of 3‐nitrobenzonitrile as the matrix. Copyright © 2015 John Wiley & Sons, Ltd.