Sun Qin, Chen Jing, Zhang Hao, Ding Shiming, Li Zhu, Williams Paul N, Cheng Hao, Han Chao, Wu Longhua, Zhang Chaosheng
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University , Nanjing 210098, China.
Anal Chem. 2014 Mar 18;86(6):3060-7. doi: 10.1021/ac404025e. Epub 2014 Feb 24.
A high-capacity diffusive gradients in thin films (DGT) technique has been developed for measurement of total dissolved inorganic arsenic (As) using a long shelf life binding gel layer containing hydrous zirconium oxide (Zr-oxide). Both As(III) and As(V) were rapidly accumulated in the Zr-oxide gel and could be quantitatively recovered by elution using 1.0 M NaOH for freshwater or a mixture of 1.0 M NaOH and 1.0 M H2O2 for seawater. DGT uptake of As(III) and As(V) increased linearly with deployment time and was independent of pH (2.0-9.1), ionic strength (0.01-750 mM), the coexistence of phosphate (0.25-10 mg P L(-1)), and the aging of the Zr-oxide gel up to 24 months after production. The capacities of the Zr-oxide DGT were 159 μg As(III) and 434 μg As(V) per device for freshwater and 94 μg As(III) and 152 μg As(V) per device for seawater. These values were 5-29 times and 3-19 times more than those reported for the commonly used ferrihydrite and Metsorb DGTs, respectively. Deployments of the Zr-oxide DGT in As-spiked synthetic seawater provided accurate measurements of total dissolved inorganic As over the 96 h deployment, whereas ferrihydrite and Metsorb DGTs only measured the concentrations accurately up to 24 and 48 h, respectively. Deployments in soils showed that the Zr-oxide DGT was a reliable and robust tool, even for soil samples heavily polluted with As. In contrast, As in these soils was underestimated by ferrihydrite and Metsorb DGTs due to insufficient effective capacities, which were likely suppressed by the competing effects of phosphate.
已开发出一种高容量薄膜扩散梯度（DGT）技术，用于使用含有水合氧化锆（Zr-氧化物）的长保质期结合凝胶层来测量总溶解无机砷（As）。As(III)和As(V)都能迅速在Zr-氧化物凝胶中积累，并且可以通过使用1.0 M NaOH洗脱淡水或使用1.0 M NaOH和1.0 M H2O2的混合物洗脱海水来定量回收。As(III)和As(V)的DGT吸收量随部署时间呈线性增加，并且与pH（2.0 - 9.1）、离子强度（0.01 - 750 mM）、磷酸盐（0.25 - 10 mg P L(-1)）的共存以及Zr-氧化物凝胶生产后长达24个月的老化无关。对于淡水，每个装置的Zr-氧化物DGT容量为159 μg As(III)和434 μg As(V)，对于海水，每个装置为分别为94 μg As(III)和152 μg As(V)。这些值分别比常用的水铁矿和Metsorb DGT报告的值高5 - 29倍和3 - 19倍。在添加了As的合成海水中部署Zr-氧化物DGT，在96小时的部署过程中能够准确测量总溶解无机As，而水铁矿和Metsorb DGT分别仅在24小时和48小时内准确测量浓度。在土壤中的部署表明，Zr-氧化物DGT是一种可靠且强大的工具，即使对于受As严重污染的土壤样品也是如此。相比之下，由于有效容量不足，这些土壤中的As被水铁矿和Metsorb DGT低估，这可能受到磷酸盐竞争效应的抑制。
