Department of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 3GP, UK.
Anal Chim Acta. 2010 Mar 3;662(1):1-8. doi: 10.1016/j.aca.2009.12.038. Epub 2010 Jan 11.
Contamination of groundwater with arsenic (As) is a major health risk through contamination of drinking and irrigation water supplies. In geochemically reducing conditions As is mostly present as As(III), its most toxic species. Various methods exist to determine As in water but these are not suitable for monitoring arsenic speciation at its original pH and without preparation. We present a method that uses cathodic stripping voltammetry (CSV) to determine reactive As(III) at a vibrating, gold, microwire electrode. The As(III) is detected after adsorptive deposition of As(OH)(3)(0), followed by a potential scan to measure the reduction current from As(III) to As(0). The method is suitable for waters of pH 7-12, has an analytical range of 1 nM to 100 microM As (0.07-7500 ppb) and a limit of detection of 0.5 nM with a 60 s deposition time. The As speciation protocol involves measuring reactive As(III) by CSV at the original pH and acidification to pH 1 to determine inorganic As(III)+As(V) by anodic stripping voltammetry (ASV) using the same electrode. Total dissolved As is determined by ASV after UV-digestion at pH 1. The method was successfully tested on various raw groundwater samples from boreholes in the UK and West Bengal.
地下水砷（As）污染是通过污染饮用水和灌溉用水供应而导致的主要健康风险。在地球化学还原条件下，砷主要以其毒性最大的形态三价砷（As(III)）存在。目前存在多种方法可用于测定水中的砷，但这些方法不适用于在原始 pH 值下且无需预处理的情况下监测砷形态。我们提出了一种使用阴极剥离伏安法（CSV）在振动的金微丝电极上测定反应性三价砷（As(III)）的方法。在吸附沉积砷（III）氢氧化物（As(OH)(3)(0)）后，通过电势扫描来测量从三价砷到零价砷（As(0)）的还原电流来检测砷（III）。该方法适用于 pH 值为 7-12 的水样，分析范围为 1 nM 至 100 microM As（0.07-7500 ppb），检测限为 0.5 nM，沉积时间为 60 秒。砷形态分析协议包括在原始 pH 值下通过 CSV 测定反应性三价砷（As(III)），然后酸化至 pH 1 以通过使用相同电极的阳极剥离伏安法（ASV）测定无机三价砷（As(III)+As(V)）。总溶解砷（Total dissolved As）通过在 pH 1 下进行紫外线消解后用 ASV 测定。该方法成功地测试了来自英国和西孟加拉邦钻孔的各种原始地下水样本。
