Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea.
Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea.
Talanta. 2018 May 1;181:366-372. doi: 10.1016/j.talanta.2018.01.034. Epub 2018 Feb 3.
The World Health Organization (WHO) guideline states that the total arsenic concentration in drinking water must not exceed 10 ppb. However, arsenic toxicity varies significantly, with inorganic arsenic species being more toxic than organic species. Arsenic speciation is therefore important for evaluating the health risks from arsenic-contaminated drinking water. Capillary electrophoresis provides the necessary high performance separation to determine arsenic species in water, but its sensitivity with absorbance detection is far below than needed. Using a coated capillary, several on-line sample preconcentration techniques such as large volume sample stacking with an electroosmotic flow pump, field amplified sample injection (FASI), transient isotachophoresis (tITP), electrokinetic supercharging (EKS) combining FASI and tITP, and counter flow (CF)-EKS, were therefore investigated. With CF-EKS using phosphate and N-cyclohexyl-2-aminoethanesulfonate as leading and terminating electrolytes, respectively, standard samples of arsenite, arsenate, monomethylarsonic acid, and dimethylarsinic acid were preconcentrated from 6,300- to 45,000-fold. The limits of detection obtained with UV absorbance detection were 0.08-0.3 ppb As. For a spring water sample spiked with the four arsenic species, LODs of 2-9 ppb As were obtained, which are lower than the WHO guideline of 10 ppb total As.
世界卫生组织（WHO）准则规定，饮用水中的总砷浓度不得超过 10 ppb。然而，砷的毒性差异很大，无机砷比有机砷更具毒性。因此，砷形态分析对于评估受砷污染饮用水的健康风险非常重要。毛细管电泳提供了必要的高性能分离，以确定水中的砷形态，但它与吸收检测的灵敏度远远低于所需的水平。使用涂层毛细管，研究了几种在线样品预浓缩技术，例如使用电动流泵的大体积样品堆积、场放大样品进样（FASI）、瞬态等速电泳（tITP）、电动超浓缩（EKS）结合 FASI 和 tITP，以及逆流（CF）-EKS。使用 CF-EKS 时，分别使用磷酸盐和 N-环己基-2-氨基乙磺酸作为先导和终止电解质，将亚砷酸盐、砷酸盐、一甲基砷酸和二甲基砷酸的标准样品从 6300 倍浓缩到 45000 倍。使用紫外吸收检测获得的检出限为 0.08-0.3 ppb As。对于加标了这四种砷形态的泉水样品，LOD 为 2-9 ppb As，低于 WHO 总砷 10 ppb 的准则。
