Pearson Holly B C, Galceran Josep, Companys Encarna, Braungardt Charlotte, Worsfold Paul, Puy Jaume, Comber Sean
Biogeochemistry Research Centre, Plymouth University, Drake Circus, Plymouth, PL4 8AA, UK.
University of Lleida, Departament de Química, UdL and Agrotecnio. Av. Rovira Roure 191, 25198, Lleida, Spain.
Anal Chim Acta. 2016 Mar 17;912:32-40. doi: 10.1016/j.aca.2016.01.035. Epub 2016 Jan 27.
Zinc (Zn) has been classified as a "Specific Pollutant" under Annex VIII of the EU Water Framework Directive by two thirds of the EU member states. As a result, the UK Environmental Quality Standard (EQS) for Transitional and Coastal (TrAC) Waters has been reduced from 612 nM to 121 nM total dissolved Zn. It is widely accepted that the free metal ion ([Zn(2+)]) is the most bioavailable fraction, but there are few techniques available to determine its concentration in these waters. In this work, Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) has been applied, for the first time, to determine [Zn(2+)] in estuarine waters. The AGNES method had a mean RSD of ±18%, a (deposition time dependent) limit of detection of 0.73 nM and a [Zn(2+)] recovery of 112 ± 19% from a certified reference material (BCR-505; Estuarine Water). AGNES results for 13 estuarine samples (salinity 0.1-31.9) compared well (P = 0.02) with Competitive Ligand Exchange Cathodic Stripping Voltammetry (CLE-AdCSV) except for one sample. AGNES requires minimal sample manipulation, is unaffected by adsorption of interfering species at the electrode surface and allows direct determination of free zinc ion concentrations. Therefore AGNES results can be used in conjunction with ecotoxicological studies and speciation modelling to set and test compliance with water quality standards.
三分之二的欧盟成员国已将锌（Zn）列为欧盟水框架指令附件八中的“特定污染物”。因此，英国过渡性和沿海水域（TrAC）的环境质量标准（EQS）中，总溶解锌的含量已从612 nM降至121 nM。人们普遍认为，游离金属离子（[Zn(2+)]）是生物可利用性最高的部分，但目前几乎没有技术可用于测定这些水域中其浓度。在这项工作中，首次应用了无梯度和能斯特平衡溶出法（AGNES）来测定河口水中的[Zn(2+)]。AGNES方法的平均相对标准偏差为±18%，检测限（取决于沉积时间）为0.73 nM，从有证标准物质（BCR-505；河口海水）中回收的[Zn(2+)]为112±19%。除一个样品外，13个河口样品（盐度0.1 - 31.9）的AGNES结果与竞争配体交换阴极溶出伏安法（CLE-AdCSV）结果比较良好（P = 0.02）。AGNES所需的样品处理极少，不受电极表面干扰物质吸附的影响，并可直接测定游离锌离子浓度。因此，AGNES结果可与生态毒理学研究和形态模拟结合使用，以设定和测试是否符合水质标准。
