Laboratoire d'Analyses en Soutien aux Exploitants du CEA de SACLAY, DEN/DANS/DPC/SEARS/LASE, Bât 459, 91191 Gif-sur-Yvette, France.
J Chromatogr A. 2013 Feb 8;1276:20-5. doi: 10.1016/j.chroma.2012.10.055. Epub 2012 Dec 3.
EDTA is a chelating agent that has been used in decontamination processes. Its quantification is required for nuclear waste management because it affects the mobility of radionuclides and metals in environment and, thus, can harm the safety of the storage. Ion-pair chromatography coupled with electrospray mass spectrometry detection is a convenient method for quantitative analysis of EDTA but EDTA should be present as a single anionic chelate form. However, radioactive liquid wastes contain high concentrations of heavy metals and salts and consequently, EDTA is present as several chelates. Speciation studies were carried out to choose a metal cation to be added in excess to the solution to obtain a major chelate form. Fe is the predominant cation and Fe(III)-EDTA is thermodynamically favored but these speciation studies showed that ferric hydroxide precipitated above pH 2. Consequently, it was not possible to quantify EDTA as Fe(III)-EDTA complex. Therefore, Ni(2+) was chosen but its use implied pretreatment with a base of the solution to eliminate Fe. Deuterated EDTA was used as tracer in order to validate the whole procedure, from the treatment with a base to the final analysis by HPLC-ESI-MS. This analytical method was successfully applied for EDTA quantification in two real effluents resulting from a nuclear liquid waste process. A recovery rate between 60 and 80% was obtained. The limit of detection of this method was determined at 34×10(-9)mol L(-1).
EDTA 是一种螯合剂，已用于去污过程。由于它影响放射性核素和金属在环境中的迁移性，因此对核废料管理很重要，它的定量分析是必要的。离子对色谱法结合电喷雾质谱检测是 EDTA 定量分析的一种方便方法，但 EDTA 应呈单一阴离子螯合形式存在。然而，放射性液体废物中含有高浓度的重金属和盐，因此 EDTA 存在于几种螯合物中。形态研究是为了选择要加入过量溶液中的金属阳离子，以获得主要的螯合形式。Fe 是主要的阳离子，Fe(III)-EDTA 在热力学上是有利的，但这些形态研究表明，Fe(OH)3 在 pH 高于 2 时沉淀。因此，不可能将 EDTA 定量为 Fe(III)-EDTA 络合物。因此，选择了 Ni(2+)，但其使用需要对溶液进行碱预处理以去除 Fe。氘代 EDTA 被用作示踪剂，以验证从碱处理到最终通过 HPLC-ESI-MS 分析的整个过程。该分析方法成功地应用于从核液体废物过程中得到的两种实际流出物中的 EDTA 定量。回收率在 60%至 80%之间。该方法的检测限确定为 34×10(-9)mol L(-1)。
