Laboratorio Of Quimica Legal

Vitória, Brazil

Laboratorio Of Quimica Legal

Vitória, Brazil
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De Carvalho T.C.,Federal University of Goais | Tosato F.,Federal University of Espirito Santo | Souza L.M.,Federal University of Espirito Santo | Santos H.,Federal University of Espirito Santo | And 9 more authors.
Forensic Science International | Year: 2016

Thin layer chromatography (TLC) is a simple and inexpensive type of chromatography that is extensively used in forensic laboratories for drugs of abuse analysis. In this work, TLC is optimized to analyze cocaine and its adulterants (caffeine, benzocaine, lidocaine and phenacetin) in which the sensitivity (visual determination of LOD from 0.5 to 14 mg mL-1) and the selectivity (from the study of three different eluents: CHCl3:CH3OH:HCOOHglacial (75:20:5 v%), (C2H5)2O:CHCl3 (50:50 v%) and CH3OH:NH4OH (100:1.5 v%)) were evaluated. Aiming to improve these figures of merit, the TLC spots were identified and quantified (linearity with R2 > 0.98) by the paper spray ionization mass spectrometry (PS-MS), reaching now lower LOD values (>1.0 μg mL-1). The method developed in this work open up perspective of enhancing the reliability of traditional and routine TLC analysis employed in the criminal expertise units. Higher sensitivity, selectivity and rapidity can be provided in forensic reports, besides the possibility of quantitative analysis. Due to the great simplicity, the PS(+)-MS technique can also be coupled directly to other separation techniques such as the paper chromatography and can still be used in analyses of LSD blotter, documents and synthetic drugs. © 2016 Elsevier Ireland Ltd.

Nascimento I.R.,Federal University of Espirito Santo | Costa H.B.,Federal University of Espirito Santo | Souza L.M.,Federal University of Espirito Santo | Soprani L.C.,Federal University of Espirito Santo | And 2 more authors.
Analytical Methods | Year: 2015

The Cannabis sativa L. plant is a species rich in a variety of cannabinoid compounds and Δ9-tetrahydrocannabinol (Δ9-THC) has been reported as a main psychotropic substance. In this study, electrospray ionization (ESI), coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), was used in order to perform a direct and fast analysis of street marijuana samples. ESI(-)-FT-ICR MS detected 21 cannabinoid species in the deprotonated form, [M - H]-. Other species were detected in regions of m/z 600-800 and 800-1000, corresponding to dimers and trimers of cannabinoids. In addition, ESI(-) was better able to analyze the chemical profile of terpenophenolic species (CcHhOo) than ESI(+). ESI(+)-FT-ICR MS detected the presence of adulterants such as cocaine, lidocaine, and nicotine. Finally, the sensitivity of fast blue B colorimetric testing was also evaluated and the results were compared to the ESI(-)FT-ICR MS data. © 2015 The Royal Society of Chemistry.

Conceicao V.N.,Federal University of Espirito Santo | Souza L.M.,Federal University of Espirito Santo | Merlo B.B.,Laboratorio Of Quimica Legal | Filgueiras P.R.,University of Campinas | And 2 more authors.
Quimica Nova | Year: 2014

Cocaine is usually seized mixed with a wide variety of adulterants such as benzocaine, lidocaine, caffeine, and procaine. The forensic identification of cocaine in these street drug mixtures is normally performed using colorimetric testing kits, but these tests may suffer from interferences, producing false-positive results. Here, we describe the use of analytical techniques including attenuated total reflection Fourier transform infrared (ATRFTIR) and ultraviolet-visible (UV-VIS) spectroscopies to distinguish between cocaine and other adulterants (lidocaine, promethazine, powdered milk and yeast) that yield positive results on the Scott test using the thiocyanate cobalt reagent. A further 13 substances were also analyzed using the Scott test.

Vanini G.,Federal University of Espirito Santo | Souza R.M.,Federal University of Espirito Santo | Destefani C.A.,Federal University of Espirito Santo | Destefani C.A.,Laboratorio Of Quimica Legal | And 5 more authors.
Microchemical Journal | Year: 2014

A new analytical method is proposed for the collection and quantification of gunshot residues (GSRs) from firearms using inductively coupled plasma optical emission spectrometry (ICP OES). Lead (Pb), barium (Ba) and antimony (Sb) concentrations in GSR from .38 caliber Taurus® handguns were monitored, and three important methodologies were evaluated such as: i) the collection region of the hand of the shooter; ii) tape-type versus swab collectors; and iii) GSR quantification from the right and left hands. Pb, Ba and Sb were found in four of the hand regions analyzed (palm, back, thumb and forefinger palm (TF-palm), and thumb and forefinger back (TF-back)), with their concentrations increasing as a function of the number of shots (one, three and five). Lead was found to be the most abundant species present. In terms of relative analytical sensitivity, higher concentrations of these three elements are mainly found in the back, TF-palm and TF-back regions. The effect of hand washing was also evaluated, which the TF-palm and the TF-back regions maintained sensitivity for the detection of three elements (concentrations higher than 4.56μgL-1) for only three and five shots. Among the collection devices analyzed, swab collectors (dry, moistened with EDTA, and moistened with water) presented higher sensitivity than tape-type collectors (adhesive, double-sided and adhesive-plaster). Additionally, swabs are a more economical collection device, providing a simple and fast collection method that does not require microwave digestion. Pb, Ba and Sb concentrations were also evaluated on the left and right hands. It was observed that Pb is mainly found on the right hand, whereas Ba and Sb concentrations are similar on both hands. ICP OES is therefore a powerful tool for GSR analysis, providing multielemental quantification of Pb, Ba and Sb. © 2014 Elsevier B.V.

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