Rusinek Cory A, Bange Adam, Warren Mercedes, Kang Wenjing, Nahan Keaton, Papautsky Ian, Heineman William R
Department of Chemistry, University of Cincinnati , Cincinnati, Ohio 45221-0172, United States.
Department of Chemistry, Xavier University , Cincinnati, Ohio 45207-4221, United States.
Anal Chem. 2016 Apr 19;88(8):4221-8. doi: 10.1021/acs.analchem.5b03381. Epub 2016 Apr 1.
Though an essential metal in the body, manganese (Mn) has a number of health implications when found in excess that are magnified by chronic exposure. These health complications include neurotoxicity, memory loss, infertility in males, and development of a neurologic psychiatric disorder, manganism. Thus, trace detection in environmental samples is increasingly important. Few electrode materials are able to reach the negative reductive potential of Mn required for anodic stripping voltammetry (ASV), so cathodic stripping voltammetry (CSV) has been shown to be a viable alternative. We demonstrate Mn CSV using an indium tin oxide (ITO) working electrode both bare and coated with a sulfonated charge selective polymer film, polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-sulfonate (SSEBS). ITO itself proved to be an excellent electrode material for Mn CSV, achieving a calculated detection limit of 5 nM (0.3 ppb) with a deposition time of 3 min. Coating the ITO with the SSEBS polymer was found to increase the sensitivity and lower the detection limit to 1 nM (0.06 ppb). This polymer modified electrode offers excellent selectivity for Mn as no interferences were observed from other metal ions tested (Zn(2+), Cd(2+), Pb(2+), In(3+), Sb(3+), Al(3+), Ba(2+), Co(2+), Cu(2+), Ni(3+), Bi(3+), and Sn(2+)) except Fe(2+), which was found to interfere with the analytical signal for Mn(2+) at a ratio 20:1 (Fe(2+)/Mn(2+)). The applicability of this procedure to the analysis of tap, river, and pond water samples was demonstrated. This simple, sensitive analytical method using ITO and SSEBS-ITO could be applied to a number of electroactive transition metals detectable by CSV.
尽管锰（Mn）是人体必需的金属，但过量的锰会对健康产生诸多影响，长期接触会使这些影响加剧。这些健康问题包括神经毒性、记忆力减退、男性不育以及神经精神疾病锰中毒的发展。因此，环境样品中的痕量检测变得越来越重要。很少有电极材料能够达到阳极溶出伏安法（ASV）所需的锰的负还原电位，所以阴极溶出伏安法（CSV）已被证明是一种可行的替代方法。我们展示了使用裸铟锡氧化物（ITO）工作电极以及涂有磺化电荷选择性聚合物膜聚苯乙烯 - 嵌段 - 聚（乙烯 - 无规 - 丁烯） - 嵌段 - 聚苯乙烯磺酸盐（SSEBS）的ITO工作电极进行锰的CSV检测。事实证明，ITO本身是用于锰CSV检测的优秀电极材料，在沉积时间为3分钟时，计算得出的检测限为5 nM（0.3 ppb）。发现用SSEBS聚合物涂覆ITO可提高灵敏度并将检测限降低至1 nM（0.06 ppb）。这种聚合物修饰电极对锰具有出色的选择性，因为在所测试的其他金属离子（Zn(2+)、Cd(2+)、Pb(2+)、In(3+)、Sb(3+)、Al(3+)、Ba(2+)、Co(2+)、Cu(2+)、Ni(3+)、Bi(3+)和Sn(2+)）中未观察到干扰，除了Fe(2+)，它在20:1（Fe(2+)/Mn(2+)）的比例下会干扰Mn(2+)的分析信号。该方法对自来水、河水和池塘水样分析的适用性得到了证明。这种使用ITO和SSEBS - ITO的简单、灵敏的分析方法可应用于许多可通过CSV检测的电活性过渡金属。
