Melo Luisa Célia, Salazar-Banda Giancarlo Richard, Machado Sergio Antonio Spinola, de Lima-Neto Pedro, De Souza Djenaine, Correia Adriana Nunes
Universidade Federal do Ceará, Centro de Ciências, Departamento de Química Analítica e Físico Química, Fortaleza, CE, Brazil.
Talanta. 2009 Oct 15;79(5):1216-22. doi: 10.1016/j.talanta.2009.04.024. Epub 2009 Apr 19.
This paper describes the use of a dental amalgam electrode (DAE) to evaluate the electrochemical behaviour and to develop an electroanalytical procedure for determination of diquat herbicide in natural water and potato samples. The work was based on the square wave voltammetry responses of diquat, which presented two well-defined and reversible reduction peaks, at -0.56 V (peak 1) and -1.00 V (peak 2). The experimental and voltammetric parameters were optimised, and the analytical curves were constructed and compared to similar curves performed by high performance liquid chromatography coupled to ultraviolet-visible spectrophotometric detector (HPLC/UV-vis). The responses were directly proportional to diquat concentration in a large interval of concentration, and the calculated detection limits were very similar, around 10 microg L(-1) (10 ppb) for voltammetric and chromatographic experiments. These values were lower than the maximum residue limit established for natural water by the Brazilian Environmental Agency. The recovery percentages in pure electrolyte, natural water and potato samples showed values from 70% to 130%, demonstrating that the voltammetric methodology proposed is suitable for determining any contamination by diquat in different samples, minimising the toxic residues due to the use of liquid mercury or the adsorptive process relative to use of other solid surfaces.
本文描述了使用牙科汞合金电极（DAE）来评估电化学行为，并开发一种用于测定天然水和马铃薯样品中敌草快除草剂的电分析方法。这项工作基于敌草快的方波伏安响应，其呈现出两个明确且可逆的还原峰，分别位于-0.56 V（峰1）和-1.00 V（峰2）。对实验和伏安参数进行了优化，构建了分析曲线，并与采用高效液相色谱-紫外-可见分光光度检测器（HPLC/UV-vis）得到的类似曲线进行了比较。在较大的浓度区间内，响应与敌草快浓度成正比，伏安法和色谱法实验计算出的检测限非常相似，约为10 μg L⁻¹（10 ppb）。这些值低于巴西环境机构规定的天然水最大残留限量。在纯电解质、天然水和马铃薯样品中的回收率为70%至130%，表明所提出的伏安法适用于测定不同样品中敌草快的任何污染，相对于使用其他固体表面的吸附过程或使用液态汞而言，可将有毒残留物降至最低。
