Distinguishing isomeric representatives of "bath salts", "plant food", "spice", or "legal high" remains a challenge for analytical chemistry. In this work, we used vacuum ultraviolet spectroscopy combined with gas chromatography to address this issue on a set of forty-three designer drugs. All compounds, including many isomers, returned differentiable vacuum ultraviolet/ultraviolet spectra. The pair of 3- and 4-fluoromethcathinones (m/z 181.0903), as well as the methoxetamine/meperidine/ethylphenidate (m/z 247.1572) triad, provided very distinctive vacuum ultraviolet spectral features. On the contrary, spectra of 4-methylethcathinone, 4-ethylmethcathinone, 3,4-dimethylmethcathinone triad (m/z 191.1310) displayed much higher similarities. Their resolution was possible only if pure standards were probed. A similar situation occurred with the ethylone and butylone pair (m/z 221.1052). On the other hand, majority of forty-three drugs was successfully separated by gas chromatography. The detection limits for all the drug standards were in the 2-4 ng range (on-column amount), which is sufficient for determinations of seized drugs during forensics analysis. Further, state-of-the-art time-dependent density functional theory was evaluated for computation of theoretical absorption spectra in the 125-240 nm range as a complementary tool.

Department of Chemistry and Biochemistry The University of Texas at Arlington Arlington TX USA

Department of Forensic Science George Washington University Washington DC USA

Institute of Microbiology v v i The Czech Academy of Sciences Prague Czech Republic; Biomedical Research Center Slovak Academy of Sciences Bratislava Slovakia

Institute of Microbiology v v i The Czech Academy of Sciences Prague Czech Republic; Regional Centre of Advanced Technologies and Materials Department of Analytical Chemistry Faculty of Science of Palacky University in Olomouc Olomouc Czech Republic

Regional Centre of Advanced Technologies and Materials Department of Analytical Chemistry Faculty of Science of Palacky University in Olomouc Olomouc Czech Republic

VUV Analytics Inc Cedar Park TX USA

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Cyclic Ion Mobility of Isomeric New Psychoactive Substances Employing Characteristic Arrival Time Distribution Profiles and Adduct Separation