Combination of in Situ Preconcentration and On-Site Analysis for Phosphate Monitoring in Fresh Waters

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• 作者：Weijia Li ; Lai Yoke Lee ; Lin Yue Lanry Yung ; Yiliang He ; Choon Nam Ong
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：August 5, 2014
• 年：2014
• 卷：86
• 期：15
• 页码：7658-7665
• 全文大小：298K
• ISSN：1520-6882

文摘

Excess nutrients of phosphorus and nitrogen would lead to adverse impacts on a water body. It is important that their concentrations in a dynamic water ecosystem are measured accurately and constantly for an early warning before occurrences of algal blooms and for environmental management. Nevertheless, on-site measurements by existing technologies are often limited by the inherent sensitivities. In this study, a portable system for dissolved phosphate monitoring in freshwater based on the diffusive gradients in thin films (DGT) technique was developed. A polydiallydimethylammonium chloride (PDA) aqueous solution and a dialysis membrane were used as a binding phase and a diffusive layer in this preconcentration device, respectively. The binding properties of the PDA solution were evaluated in solutions of different pH (3 to 9) and varying concentrations of anions (2.0鈥?0 mM). The amount of phosphates preconcentrated in the devices was measured by ultraviolet鈥搗isible (UV) spectroscopy to obtain the concentrations in waters without elution steps. The devices were validated in synthetic river water with good agreement with the theoretical prediction and in natural river water. A system combining this preconcentration device and a compact detection chamber equipped with a pair of light emitting diodes (LED) was studied in lab synthetic solutions for on-site monitoring of phosphate concentrations and their fluctuations.