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Diffusion characteristics of agarose hydrogel used in diffusive gradients in thin films for measurements of cations and anions

文献类型: 外文期刊

作者: Wang, Yan 1 ; Ding, Shiming 1 ; Gong, Mengdan 1 ; Xu, Shiwei 2 ; Xu, Weimin 2 ; Zhang, Chaosheng 3 ;

作者机构: 1.Chinese Acad Sci, Nanjing Inst Geog & Limnol, State Key Lab Lake Sci & Environm, Nanjing 210008, Jiangsu, Peoples R China

2.Jiangsu Acad Agr Sci, Cent Lab, Nanjing 210008, Jiangsu, Peoples R China

3.Natl Univ Ireland, Sch Geog & Archaeol, Int Network Environm & Hlth, Galway, Ireland

关键词: Agarose;Diffusion coefficient;Diffusive gel;Diffusive gradients in thin films;Cation;Anion

期刊名称:ANALYTICA CHIMICA ACTA ( 2020影响因子:6.558; 五年影响因子:6.228 )

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收录情况: SCI

摘要: The agarose hydrogel has been increasingly used as a diffusive layer in diffusive gradients in thin films (DGT) measurements. However its diffusive characteristics have not been examined in detail. In this study, the performance of agarose gel was tested in DGT measurements of eight cations (Fe(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), and Cd(II)) and eight anions (P(V), As(V), Cr(VI), Mo(VI), Sb(V), Se(VI), V(V), and W(VI)). It was found that the thickness of agarose, a key parameter in the calculation of DGT measured concentration, remained unchanged after hydration followed by storage under the following conditions: pH 2-11, ionic strength 0-1.0 M, temperature 4-40 degrees C, and with the storage time extending to 300 d. Enrichment of cations and repelling of anions were observed in the gel under the ionic strengths of < 2-3 mM and < 1 mM (NaNO3), respectively, which was attributed to the electrostatic interactions of these ions with the fixed negatively charged groups (mainly pyruvate) in the gel. The diffusion coefficients of cations and anions through the agarose gel (plus a PVDF filter membrane) were on average 1.10 +/- 0.04 times of the reported diffusion coefficients through the agarose cross-linked polyacrylamide (APA) hydrogel, typically used in DGT technique. The working pH ranges for the agarose gel-assembled DGTs were 4-10 and 5-9 for anions and cations, respectively. The use of agarose gel, either individually or along with different filter membranes, affected the overall diffusion rates of cations and anions. The measured DGT concentrations of cations and anions in filtered natural freshwater and seawater were mostly in line with those measured directly. The results showed that the agarose gel can be used as one of the standard diffusive layers in DGT measurements for a wide range of inorganic and organic analytes. (C) 2016 Elsevier B.V. All rights reserved.

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[1]Simultaneous measurements of cations and anions using diffusive gradients in thin films with a ZrO-Chelex mixed binding layer. Wang, Yan,Ding, Shiming,Shi, Lei,Gong, Mengdan,Xu, Shiwei,Zhang, Chaosheng.

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