Improved Diffusive Gradients in Thin Films (DGT) Measurement of Total Dissolved Inorganic Arsenic in Waters and Soils Using a Hydrous Zirconium Oxide Binding Layer
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- 作者：Qin Sun ; Jing Chen ; Hao Zhang ; Shiming Ding ; Zhu Li ; Paul N. Williams ; Hao Cheng ; Chao Han ; Longhua Wu ; Chaosheng Zhang
- 刊名：Analytical Chemistry
- 出版年：2014
- 出版时间：March 18, 2014
- 年：2014
- 卷：86
- 期：6
- 页码：3060-3067
- 全文大小：314K
- 年卷期：v.86,no.6(March 18, 2014)
- ISSN：1520-6882
文摘
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鈥?.1), ionic strength (0.01鈥?50 mM), the coexistence of phosphate (0.25鈥?0 mg P L鈥?), and the aging of the Zr-oxide gel up to 24 months after production. The capacities of the Zr-oxide DGT were 159 渭g As(III) and 434 渭g As(V) per device for freshwater and 94 渭g As(III) and 152 渭g As(V) per device for seawater. These values were 5鈥?9 times and 3鈥?9 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.