Desenvolvimento de métodos para quantificação de drogas em matrizes de interesse forense

Abstract

Drug abuse has become a worldwide problem which has serious consequences for users and society. Illicit drugs such as cocaine, cannabis, etc, and the licit ones such as prescriptiondrugs, are related to overdoses, poisonings, car accidents, homicides, and suicides. In this context, the development of sensitive and low cost analytical methods is important in evaluating these cases. In this study, analytical methods employing solid-liquid extraction with partition atlow temperature (SLE-LTP) and liquid-liquid extraction with partition at low temperature (LLELTP) and analysis by chromatographic techniques coupled with mass spectrometry have been developed. The LLE-LTP technique uses a hydrophilic solvent (acetonitrile) which is separatedfrom the aqueous phase by lowering the temperature (-20 °C). By using this method, it is possible to obtain clean extracts, even in complex matrices without clean-up step. The work consists of three parts. In the first part, the LLE-LTP procedure was applied to determine five benzodiazepine compounds in urine samples by using liquid chromatography coupled with mass spectrometry. Recoveries ranging between 61.3 and 100.4% were obtained. In the validation tests, low detection limits (1-5 mg L-1), good precision with coefficients ofvariation (CV) less than 12.5% and accuracy from 72.9 to 116.6% was obtained. The method was applied to two samples of users of diazepam. It was possible to find out not only the active ingredient, but also its metabolite oxazepam. In the second part, the LLE-LTP procedure was optimized to detect cocaine in biological matrices such as liver, blood and urine by gas chromatography-mass spectrometry. The methodswere validated and presented low limits of detection and quantification. The variation coefficient obtained in the precision assays was less than 13.4%. The addition and recovery tests assessing the accuracy of the method ranged from 69.2 to 81.9% in the matrix of blood, from 92.6 to 95.7% in urine and 95.1 to 100.4% in the liver. The validated method was successfully applied to real samples of biological matrices of post-mortem examined individuals. These samples consisted of8 liver samples, 5 urine samples and 5 blood samples.In the last part, an evaluation of organic and inorganic constituents was made on samples of "street cocaine" seized in the states of Minas Gerais and Amazonas. Organic compounds such as cocaine, caffeine, lidocaine, and benzocaine were quantified by gas chromatography-massspectrometry. Inorganic constituents such as Ca, Mg, Na, K, P, Al, Fe, Mn, Co, Cu, Cr, Mo, Ni, Pb and Zn were determined by inductively coupled plasma-optical emission spectrometry (ICPOES). Anions nitrate, chloride, nitrite, bromide, fluoride, and sulfate were determined by ionchromatography. The purity of cocaine seized in the Minas Gerais samples ranged from 6.4 to 75.3%. These samples are more adulterated than samples seized in the state of Amazonas. Caffeine was the most common adulterant in seized samples of Minas Gerais, being found in76% of them, followed by lidocaine (66.7%). Pearson correlations were obtained to try to relate the organic and inorganic constituents with the processes of adulteration and dilution of street samples of cocaine