Análise e caracterização de drogas sintéticas: integração de técnicas instrumentais e dados teóricos para apoio à identificação forense

Abstract

The global effort to combat the indiscriminate use of substances of abuse has intensified, with novel strategies continually emerging to circumvent regulatory oversight, including the development of new, uncontrolled synthetic drugs. The continuous and rapid introduction of these substances into the market poses significant challenges to the establishment of specific methodologies for their immediate analysis, thereby hindering effective regulation. Consequently, the adaptation and integration of analytical techniques are required for the reliable identification of these substances. This study aimed to analyze seized samples of synthetic drugs in order to enrich existing databases and to develop or adapt methods applicable to routine forensic laboratory procedures for compound identification. Samples were selected among those most frequently seized by the Federal Police between 2013 and 2023, including synthetic cannabinoids, cathinones, and phenylethylamines. Analytical techniques employed comprised Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, nuclear magnetic resonance (NMR), UV-Vis spectroscopy, X-ray diffraction (XRD), and thermal analysis. Single-crystal X-ray diffraction (SC-XRD) was applied to elucidate molecular structures and to provide reference materials for other analytical approaches. Combined with powder X-ray diffraction (PXRD), this technique enabled presumptive identification of samples and assessment of impurities through comparison with structures reported in the Cambridge Crystallographic Data Centre (CCDC). Based on the deposited structures, a PXRD database was established, allowing both identification and purity evaluation of seized materials. Thermal analysis revealed the presence of mixtures in several samples, with adulterants such as oleamide and caffeine interfering with the thermal degradation of synthetic cathinones. For phenylethylamines, degradation was attributed to interactions with the gas chromatography–mass spectrometry (GC-MS) column at elevated oven temperatures. The synthetic cannabinoid MDMB-4EN-PINACA exhibited thermal instability, with degradation initiated by ester bond cleavage and fragmentation at moderate temperatures (188 °C). Furthermore, FTIR spectrum simulation achieved 50% accuracy in preliminary identification and demonstrated potential for classification according to drug classes.