Development of solid-phase extraction technique for ICP-MS analysis of iodine-129 in environmental samples; Comparative study of anion-exchange and silver ion-supported resins on isolation of Iodine-129 from interference elements

Aoki, Jo; Matsueda, Makoto   ; Koarai, Kazuma   ; Terashima, Motoki  ; Fujiwara, Kenso ; Abe, Hironobu 

In order to analyze extremely low concentrations of I in environmental samples by ICP-MS with high sensitivity and rapidity, it is necessary to remove interfering elements (Na, Mg, K, Ca, Mo, Cd and In) using a pretreatment method with Solid-phase Extraction Resin. Anion Exchange Resins with amino groups have been widely used as Solid-phase Extraction Resins, while Ag+ Supported Resins have also been widely used in recent years. It is necessary to optimize the pretreatment technique based on characteristics of the resins. In this study, we compared in terms of separation of I from matrix elements (Na, Mg, K, Ca, Mo, Cd and In) for DOWEX1-X8, AG 1-X8 and CL Resin, and investigated their suitability for ICP-MS analysis of I in environmental samples. The results of adsorption and elution experiments showed that all resins examined uptake and elute I quantitatively. CL Resin showed the highest removal performance of interfering elements, with 3.1% of Mo remaining, but other interfering elements were removed below the detection limit of ICP-MS. However, the Mo remained after the CL Resin treatment could interfere the ICP-MS measurement of I, based on the consideration of ratio of I and Mo. The eluate from CL Resin was treated with a Cation exchange resin (DOWEX 50WX8). As a result, Mo in the eluate was removed by up to 98% and the interference from Mo was reduced to measurable level. Therefore, the pretreatment method using CL Resin in combination with DOWEX 50WX8 is effective for ICP-MS analysis of I at extremely low concentrations (background level).