Voltammetric determination of cocaine in confiscated samples using a cobalt hexacyanoferrate film-modified electrode.
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 NaClO(4) 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 NaClO(4) 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 íons, 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(-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(-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.
Oiye
Erica Naomi
EN
Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Departamento de Química, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Figueiredo
Natalia Biziak de
NB
Andrade
José Fernando de
JF
Tristão
Heloisa Maria
HM
Oliveira
Marcelo Firmino de
MF