Comparação de métodos de análises para avaliação do perfil químico de amostras de cocaína apreendidas no estado do Rio de Janeiro

Abstract

One hundred and fifty samples were analyzed for suspected cocaine content. The samples were seized by Polícia Civil do Estado do Rio de Janeiro from the year 2016 to 2017 on the city of Rio de Janeiro, Baixada Fluminense and Costa Verde, and 102 samples showed powder aspect and 13 samples showed crack aspect. The samples were analyzed for cocaine and adulterant contents and for the identification of diluents. The main objective of this work was to evaluate the chemical profile of cocaine (powder and crack), as well as to compare different analysis techniques. The importance of the identification and quantification of cocaine adulterants relies on their pharmacological properties, adverse effects and synergistic activities with cocaine, possibly increasing the duration of the effects, its intensity and toxicity. Preliminary tests (Scott test, Wagner test, AgNO3 precipitation, iodine / iodide test and acid hydrolysis) were initially conducted to verify the possible presence of cocaine. Cocaine and adulterants were identified and quantified by Gas Chromatography Coupled to Mass Spectroscopy (GC-MS) and Flame Ionization Detector (FID), using commercial standards of caffeine, lidocaine, phenacetin, benzocaine and purified cocaine standard. Other adulterants eventually found were identified by Mass Spectrometry with the aid of a commercial library. The detection of diluents was performed by Raman Spectroscopy and Infrared Spectroscopy (FT-IR), using the following commercial standards: calcium carbonate (CaCO3), sodium bicarbonate (NaHCO3), aluminum sulphate (Al2(SO4)3), sodium carbonate (Na2CO3), starch, sucrose, glucose, lactose and mannitol. The capacity to detect cocaine and adulterants by Raman and FT-IR spectroscopy were also evaluated, according to previous quantification performed by GC-MS. It was verified the efficiency of the preliminary tests, the differences between crack and cocaine chemical profiles and possible differences among the three main criminal gangs of the state of Rio de Janeiro. Raman Spectroscopy was more effective for the identification of inorganic diluents on cocaine, while Infrared Spectroscopy showed better identification capacity for starch. The higher amplitude and resolution of Raman bands also favored its identification capacity for cocaine and adulterants, while Infrared Spectroscopy of powder samples showed some overlapped bands that turned more difficult their discrimination. It was observed higher cocaine contents in crack samples, showing an average of 29.77 ± 14.54% of cocaine, compared to an average of 7.31 ± 3.39% in powder samples. The most frequent adulterant identified in powder samples was caffeine, that was present in 93% of the samples, while crack samples were majorly adulterated with phenacetin, that was present in 92% of the samples. Calcium carbonate, sodium bicarbonate and starch were the diluents most frequently found in powder samples. It could be observed, by statistical analysis, similarities according to the type of the samples (hydrochloride and freebase) as well as significant differences among certain criminal gangs.