Identification and differentiation of methcathinone analogs by gas chromatography‐mass spectrometry

Abstract

To overcome a number of challenges involved in analyzing methcathinone (MC) analogues, we performed gas chromatography-mass spectrometry (GC-MS) analysis, including sample preparation, of nine MC analogues - 4-methylmethcathinone, three positional isomers of fluoromethcathinones, 4-methoxymethcathinone, N-ethylcathinone, N,N-dimethylcathinone, buphedrone, and pentedrone. The MC analogues underwent dehydrogenation when the free bases were analyzed using splitless injection. Most of this thermal degradation was prevented using split injection. This indicated that a shorter residence time in the hot injector prevented decomposition. Uniquely, 2-fluoromethcathinone degraded to another product in a process that could not be prevented by the split injection. Replacing the liner with a new, clean one was also effective in preventing thermal degradation. Most of the analytes showed a substantial loss (>30%) when the free base solution in ethyl acetate was evaporated under a nitrogen stream. Adding a small amount of dimethylformamide as a solvent keeper had a noticeable effect, but it did not completely prevent the loss. Three positional isomers of fluoromethcathinones were separated with baseline resolution by heptafluorobutyrylation with a slow column heating rate (8 °C/min) using a non-polar DB-5 ms capillary column. These results will be useful for the forensic analysis of MC analogues in confiscated materials.

Comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones

“…The use of a split mode injection and a relatively low injection port temperature (as employed in this study) can significantly reduce this phenomenon, allowing the direct injection of synthetic cathinones. This problem has been previously described by Tsujikawa et al and Kerrigan et al [12,13].…”

“…Therefore, employing a second separation technique in which the separation results are orthogonal to the initial procedure is highly desirable. TLC [7], UHPLC [8][9][10][11], GC [7,12,13], MEKC [14], and ultra high performance supercritical fluid chromatography (UHPSFC) [15,16] have all been employed for the achiral separation of synthetic cathinones, while HPLC [17][18][19], GC [17], CE [20][21][22], CEC [19], and SFC [19] have been utilized for the separation of chiral synthetic cathinones. These studies have been limited in the number of controlled substances and/or positional isomers separated.…”

“…TLC , UHPLC , GC , MEKC , and ultra high performance supercritical fluid chromatography (UHPSFC) have all been employed for the achiral separation of synthetic cathinones, while HPLC , GC , CE , CEC , and SFC have been utilized for the separation of chiral synthetic cathinones. These studies have been limited in the number of controlled substances and/or positional isomers separated.…”

The utility of silica hydride‐based stationary phases for dual‐mode ultra high performance liquid chromatography separation of synthetic cathinone positional isomers

“…GC-MS has been used to analyze synthetic cathinones [5][6][7]. Distinguishing between positional isomers by MS can be challenging, especially when substitution occurs on the benzene ring.…”

Energy‐resolved mass spectrometry for differentiation of the fluorine substitution position on the phenyl ring of fluoromethcathinones

“…In addition, their differentiation is difficult even using ion mobility spectrometry due to their similar collision cross sections. To overcome these limitations, several research groups have attempted to develop spectroscopic, spectrometric, and/or chromatographic techniques for the differentiation of the isomers . Herein, we present an alternative new and practical method to distinguish between them using electron ionization (EI)‐triple quadrupole mass spectrometry.…”