Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM, UMR CNRS 5254, Université de Pau et des Pays de l'Adour, Hélioparc Pau-Pyrénées, 2, avenue Pierre Angot, 64053 Pau Cedex 9, France.
Environ Sci Technol. 2011 Dec 15;45(24):10492-500. doi: 10.1021/es201002g. Epub 2011 Nov 28.
Hexavalent chromium (Cr(VI)) occurrence in soils is generally determined using an extraction step to transfer it to the liquid phase where it is more easily detected and quantified. In this work, the performance of the most common extraction procedure (EPA Method 3060A) using NaOH-Na(2)CO(3) solutions is evaluated using X-ray absorption near edge structure spectroscopy (XANES), which enables the quantification of Cr(VI) directly in the solid state. Results obtained with both methods were compared for three solid samples with different matrices: a soil containing chromite ore processing residue (COPR), a loamy soil, and a paint sludge. Results showed that Cr(VI) contents determined by the two methods differ significantly, and that the EPA Method 3060A procedure underestimated the Cr(VI) content in all studied samples. The underestimation is particularly pronounced for COPR. Low extraction yield for EPA Method 3060A was found to be the main reason. The Cr(VI) present in COPR was found to be more concentrated in magnetic phases. This work provides new XANES analyses of SRM 2701 and its extraction residues for the purpose of benchmarking EPA 3060A performance.
六价铬（Cr(VI)）在土壤中的存在通常通过提取步骤来确定，将其转移到液相中，以便更轻松地检测和定量。在这项工作中，使用 X 射线吸收近边结构光谱（XANES）评估了最常用的提取程序（EPA 方法 3060A）使用 NaOH-Na(2)CO(3)溶液的性能，这使得能够直接在固态下定量 Cr(VI)。对于具有不同基质的三个固体样品（含有铬铁矿加工残渣（COPR）的土壤、壤土和油漆污泥），比较了两种方法获得的结果。结果表明，两种方法确定的 Cr(VI)含量差异很大，并且 EPA 方法 3060A 程序低估了所有研究样品中的 Cr(VI)含量。对于 COPR，低估尤为明显。发现对于 EPA 方法 3060A，提取产率低是主要原因。发现 COPR 中存在的 Cr(VI)更集中在磁性相中。这项工作提供了对 SRM 2701 及其提取残渣的新 XANES 分析，目的是对 EPA 3060A 性能进行基准测试。
