Synthetic compounds structurally derived from the mild stimulant 2-amino-1-phenyl-1-propanone, known as cathinone derivatives, are one of the largest growing class of synthetic designer drugs. The characterization of these drugs is complicated by the structural diversity and similarity of compounds in the ever-growing cathinone family. This paper demonstrates the successful application of gas chromatography-electron ionization-tandem mass spectrometry (GC-EI-MS-MS) and liquid chromatography-photodiode array (LC-PDA) analysis to differentiate structurally similar derivatives including regioisomers of cathinones. Product ion spectrometry of iminium ions allows for an univocal differentiation of the studied cathinones with the same aminoalkyl moiety. Furthermore, the product ion spectrometry of acylium ions and ultraviolet spectra obtained by LC-PDA enabled differentiation of regioisomers resulting from different substitution patterns on the aromatic ring. The validity of the method was demonstrated by the analysis of N-alkylated ortho-, meta-, and para-alkylcathinones along with the scaffolds of buphedrones and pentiophenones.
Differentiation among regioisomers of synthetic cannabinoids in forensic drug analysis is a crucial issue, since all isomers are not regulated by law. New equivalent analogs obtained via minor modification of their preexisting molecules keep on emerging. Isomers formed via substitutional exchange are also a cause for concern. This study is focused on the isomeric molecules that stem from minor modifications of 5F-PB-22. The analytical properties of these molecules and methods of differentiation are reported. Scan mode analysis using gas chromatography–electron ionization-mass spectrometry (GC–EI-MS) was performed using the authentic 5F-PB-22 standard, five regioisomeric quinolinyl ester indoles, and five regioisomeric isoquinolinyl ester indoles. Because it was not possible to separate 5F-PB-22 from the 5-hydroxyquinoline isomer using GC and all analytes showed similar EI mass spectra, liquid chromatography (LC)–tandem mass spectrometry analysis was performed. Using LC, a successful separation of 5F-PB-22 from all isomers could be achieved. Based on the electrospray ionization-mass spectra, the protonated molecular ion at m/z 377.2 was selected as the precursor ion for the regioisomeric and structural isomeric differentiation. Collision-induced dissociation provides relative intensity differences in the product ions among the isomers, enabling mass spectrometric differentiation of the isomers. To our knowledge, this is the first report on mass spectrometric differentiation of 5F-PB-22 and its ten isomers.Electronic supplementary materialThe online version of this article (doi:10.1007/s11419-016-0334-9) contains supplementary material, which is available to authorized users.
Purpose One of the ongoing research subjects for forensic analysts is differentiating halogen positional isomers of newlyemerging synthetic cannabinoids. The purpose of this study is to elucidate liquid chromatographic and mass spectrometric conditions applicable to the differentiation of such derivatives. Methods High-performance liquid chromatography (HPLC) coupled with triple quadrupole mass spectrometry (QqQ-MS) and linear ion trap time-of-flight mass spectrometry (IT-TOF-MS) using electrospray ionization (ESI) in its positive ion mode were utilized to analyze six model compounds, FUB-JWH-018 and five positional isomers having structures of 1-or 2-naphthoyl-substituted 1H-indole-3-carboxylates with N-substituted positional isomeric fluorobenzyl groups (2-fluorobenzyl, 3-fluorobenzyl, and 4-fluorobenzyl). Results The chromatographic separation of the six isomers was successfully achieved by HPLC using a pentafluorophenylpropyl-bonded reversed-phase adsorbent. The positive ESI-QqQ-MS could discriminate fluorobenzyl isomers having a same naphthoyl structure via the relative abundance of the two product ions in the collision-induced dissociation reaction. ESI-IT-TOF-MS in its positive ion mode successfully distinguished three ring positional isomers in both naphthoyl scaffolds on the basis of the differences in the abundance of oxomethylium ion attributed to C 16 H 11 FNO + (m/z 252). Conclusions The use of ESI-QqQ-MS and ESI-IT-TOF-MS in its positive ion mode coupled with LC using a pentafluorophenylpropyl-bonded silica column is applicable to MS-aided differentiation and the chromatographic separation of FUB-JWH-018 positional isomers.
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