Earth and Environmental Sciences Division, Los Alamos National Laboratory, 1400 University Drive, Carlsbad, NM 88220, USA.
Anal Chim Acta. 2010 Mar 24;663(2):172-7. doi: 10.1016/j.aca.2010.01.056. Epub 2010 Feb 6.
A solvent extraction method was employed to determine ferrous and ferric iron in aqueous samples. Fe(3+) is selectively extracted into the organic phase (n-heptane) using HDEHP (bis(2-ethylhexyl) hydrogen phosphate) and is then stripped using a strong acid. After separation, both oxidation states and the total iron content were determined directly by ICP-MS analysis. This extraction method was refined to allow determination of both iron oxidation states in the presence of strong complexing ligands, such as citrate, NTA and EDTA. The accuracy of the method was verified by crosschecking using a refinement of the ferrozine assay. Presented results demonstrate the ability of the extraction method to work in a microbiological system in the presence of strong chelating agents following the bioreduction of Fe(3+) by the Shewanella alga BrY. Based on the results we report, a robust approach was defined to separately analyze Fe(3+) and Fe(2+) under a wide range of potential scenarios in subsurface environments where radionuclide/metal contamination may coexist with strongly complexing organic contaminants.
采用溶剂萃取法测定水样中的亚铁和铁。使用 HDEHP（二（2-乙基己基）磷酸氢酯）将 Fe（3+）选择性萃取到有机相中（正庚烷），然后使用强酸将其洗脱。分离后，通过 ICP-MS 分析直接测定两种价态和总铁含量。该萃取方法经过改进，可在存在强络合剂（如柠檬酸盐、NTA 和 EDTA）的情况下同时测定两种铁氧化态。通过交叉检查Ferrozine 测定法的改进，验证了该方法的准确性。所呈现的结果表明，该萃取方法在 Shewanella alga BrY 还原 Fe（3+）后，在存在强螯合剂的微生物体系中能够发挥作用。根据我们的研究结果，定义了一种稳健的方法，可在放射性核素/金属污染可能与强络合有机污染物共存的地下环境中广泛的潜在情况下，分别分析 Fe（3+）和 Fe（2+）。
