In situ sampling and speciation method for measuring dissolved phosphite at ultratrace concentrations in the natural environment.
In situ sampling and speciation method for measuring dissolved phosphite at ultratrace concentrations in the natural environment.
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DOI：
10.1016/j.watres.2018.03.031
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发表时间：
2018-06
期刊：
影响因子：
12.8
通讯作者：
Chao-xi Han;Paul N. Williams;Jinghua Ren;Zhaode Wang;Xu Fang;Di Xu;Xianchuan Xie;Jinju Geng;L. Ma;Jun Luo
中科院分区：
文献类型：
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作者：
Chao-xi Han;Paul N. Williams;Jinghua Ren;Zhaode Wang;Xu Fang;Di Xu;Xianchuan Xie;Jinju Geng;L. Ma;Jun Luo
亚磷酸盐（P+III）是新兴的化学兴趣，由于其在全球磷循环中的重要性。然而，到目前为止，由于其不稳定性/易氧化性和超痕量浓度等固有的分析挑战，仍然缺乏对P+ iii的精确测量。本文采用薄膜扩散梯度（DGT）技术，结合毛细管柱配置双离子色谱（CC-DIC），首次对溶解的P+III进行原位采样和形态分析。在完整的方法验证之前，进行了DGT洗脱体系的方法优化，以同时最大化解吸效率和CC-DIC灵敏度，以及P+III扩散系数的表征。实验室性能测试证实DGT-P+ iii的获取与pH（3.0-10.0）和离子强度（0-500 mM）无关。P+ iii的容量为45.8 μg cm−2，而P+V（高达10 mg L−1）和As+V（高达1 mg L−1）均不影响DGT-P+ iii的测量。这种新方法的功能源于本文证实的物种形态保存和P+III的双重预浓缩，在3天的部署中，定量限低至7.44 ng L−1。该方法在各种陆地/水生环境中的应用得到了证明，并在两个对比氧化还原-中生态系统中以毫米分辨率捕获了沉积物-水界面上P+ iii和P+ v的同时剖面。
Phosphite (P+III) is of emerging chemical interest due to its importance within the global phosphorus cycle. Yet, to date, precise/accurate measurements of P+IIIare still lacking due to the inherent analytical challenges linked to its instability/ease of oxidation and ultra-trace concentration. Here, we present the firstin-situsampling and speciation analysis method, for dissolved P+III, using the diffusive-gradients-in-thin-films (DGT) technique, combined with capillary-column-configured-dual-ion-chromatography (CC-DIC). Method optimization of the DGT elution regime, to simultaneously maximize desorption efficiency and CC-DIC sensitivity, along with the characterization of diffusion coefficients for P+III, were undertaken before full method validation. Laboratory-performance testing confirmed DGT-P+IIIacquisition to be independent of pH (3.0–10.0) and ionic strength (0–500 mM). The capacity for P+IIIwas 45.8 μg cm−2, while neither P+V(up to 10 mg L−1) nor As+V(up to 1 mg L−1) impacted the DGT-P+IIImeasurement. This novel method's functionality stems from the herein confirmed speciation preservation and double pre-concentration of P+III, resulting in quantification limits as low as 7.44 ng L−1for a 3-day deployment. Applications of this method in various terrestrial/aquatic environments were demonstrated and simultaneous profiles of P+IIIand P+Vacross a sediment-water interface were captured at mm resolution in two contrasting redox-mesocosm systems.