Federal University of Uberlândia (UFU), Institute of Chemistry, Uberlândia, MG, Brazil.
Federal University of Uberlândia (UFU), Institute of Chemistry, Uberlândia, MG, Brazil.
Talanta. 2021 Aug 15;231:122413. doi: 10.1016/j.talanta.2021.122413. Epub 2021 Apr 18.
Sulfide anion is a highly toxic and corrosive compound and its presence above the threshold concentrations (i.e. μmol L) in freshwaters may indicate environmental pollution. Besides, the increase in sulfide concentration results in modifications of the organoleptic proprieties of water and air. Many analytical methodologies have been designed for aqueous sulfide quantification, however, due to the high reactivity and instability of sulfide, the pursue of a simple, sensitive, selective, and portable analytical method is still a current demand. In this study, an indirect electrochemical method for the determination of sulfide based on its interaction with a palladium complex - bis(2-aminobenzoate) palladium(II) - acting as a selective chemosensor is described. The reaction leads to the demasking of the electroactive ligand 2-aminobenzoic acid (i.e. anthranilic acid) and square wave voltammetry is employed to monitor its concentration using a glassy carbon electrode (GCE). Experimental conditions were optimized and the reaction was performed in Britton-Robinson (BR) buffer at pH 5 for 4 min, providing the higher magnitude of the analytical signal. A linear relation (r > 0.99) from 3 to 30 μmol L of sulfide was obtained with a limit of detection of 0.10 μmol L. Recovery experiments using freshwater samples spiked with sulfide revealed overall satisfactory results for the limit concentration levels permitted by regulatory agencies. Therefore, the proposed methodology shows advantages in terms of portability, selectivity, sensitivity, low-cost, and easiness-to-use enabling monitoring of sulfide in a variety of waters.
硫离子是一种剧毒和腐蚀性的化合物，其在淡水中的浓度超过阈值（即μmol L）可能表明存在环境污染。此外，硫离子浓度的增加会导致水和空气中的感官特性发生变化。已经设计了许多分析方法来定量水中的硫化物，但是由于硫化物的高反应性和不稳定性，追求简单、灵敏、选择性和便携的分析方法仍然是当前的需求。在本研究中，描述了一种基于其与钯配合物-双（2-氨基苯甲酸）钯（II）相互作用的间接电化学方法，该配合物作为选择性化学传感器来测定硫化物。反应导致电活性配体 2-氨基苯甲酸（即邻氨基苯甲酸）的掩蔽作用，并使用玻碳电极（GCE）通过方波伏安法监测其浓度。优化了实验条件，反应在 pH 5 的 Britton-Robinson（BR）缓冲液中进行 4 分钟，提供了更大的分析信号幅度。在 3 至 30 μmol L 的范围内获得了线性关系（r>0.99），检测限为 0.10 μmol L。使用含硫化物的淡水样品进行的回收实验对于监管机构允许的极限浓度水平显示出总体令人满意的结果。因此，所提出的方法在便携性、选择性、灵敏度、低成本和易于使用方面具有优势，可用于监测各种水中的硫化物。
