Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Departamento de Química, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Forensic Sci Int. 2009 Nov 20;192(1-3):94-7. doi: 10.1016/j.forsciint.2009.08.004. Epub 2009 Aug 31.
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.
在这项工作中，描述了一种使用化学修饰的铂盘电极（修饰物为钴六氰合铁酸盐（CoHCFe））的快速、无损伏安法，用于在乙腈介质中检测可卡因。在含有 NaClO(4)（浓度为 0.1 mol L(-1)）的水溶液中，在铂盘（工作电极）上沉积 CoHCFe 膜。在含有 NaClO(4)（浓度为 0.1 mol L(-1)）的乙腈介质中对膜进行稳定性研究，并随后对可卡因进行伏安分析。可卡因与 CoHCFe 在膜上的可逆相互作用会导致原始峰电流呈比例下降，这是由于可卡因与钴离子形成了配合物，随后膜表面发生部分钝化，电流下降的强度用作可卡因的分析信号。可卡因的检测范围为 2.4 x 10(-4) 至 1.5 x 10(-3)mol L(-1)，线性相关系数为 0.994，检测限为 1.4 x 10(-4)mol L(-1)。用所提出的方法对缴获的样品进行分析表明可卡因含量为 37%至 95%（m/m），并通过与 HPLC 技术进行比较验证了这些结果，两种方法之间得到了很好的相关性。
