Journal
FORENSIC SCIENCE INTERNATIONAL
Volume 192, Issue 1-3, Pages 94-97Publisher
ELSEVIER IRELAND LTD
DOI: 10.1016/j.forsciint.2009.08.004
Keywords
Cocaine; Cobalt hexacyanoferrate; Forensic chemistry; Chemically modified electrodes
Categories
Funding
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)
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In this work, a fast, non destructive voltammetric method for cocaine detection in acetonitrile medium using a platinum disk electrode chemically modified with cobalt-hexacyanoferrate (CoHCFe) film is described. The deposition of CoHCFe film at platinum disk (working electrode) was carried out in aqueous solution containing NaClO4 at 0.1 mol L-1 as supporting electrolite. Stability studies of the film and subsequent voltammetric analysis of cocaine were made in acetonitrile medium with NaClO4 at 0.1 mol L-1 as supporting electrolite. A reversible interaction between cocaine and CoHCFe at the film produces a proportional decrease of original peak current, due to the formation of a complex between cocaine and cobalt ions, with subsequent partial passivation of the film surface, being the intensity of current decrease used as analytical signal for cocaine. A linear dependence of cocaine detection was carried out in the range from 2.4 x 10 x 4 to 1.5 x 10(-3) mol L-1, with a linear correlation coefficient of 0.994 and a detection limit of 1.4 x 10 x 4 mol L-1. The analysis of confiscated samples by the proposed method indicated cocaine levels from 37% to 95% (m/m) and these results were validated by comparison to HPLC technique, being obtained good correlation between both methods. (C) 2009 Elsevier Ireland Ltd. All rights reserved.
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