Determination of129I in Arctic snow by a novel analytical approach using IC-ICP-SFMS

The environmental radiation background has increased in the last century due to human nuclear activities and in this context I-129 may be used to evaluate the anthropogenic contribution to global nuclear contamination. We present a fast and novel method for iodine-129 measurements. Coupling ion chromatography and inductively coupled plasma sector field mass spectrometry (IC-ICP-SFMS) allows the determination of iodine-129 at picogram per gram levels. The capability of the Dionex IONPAC (R) AS16 column to retain iodine species in the absence of NaOH has been used to pre-concentrate 5 mL samples. Although I-129 suffers from isobaric spectral interference due to the presence of Xe-129, the IC-ICP-SFMS technique allows I-129 to be determined by removing all other isobaric interferents. Furthermore, the Xe-129 interference is sufficiently small and stable to be treated as a background correction. This strategy permits the evaluation of I-129 speciation at sub-picogram per gram levels with a limit of detection (LOD) of 0.7 pg g(-1). Thus the range of possible applications of this technique is expanded to low-concentration environmental samples such as polar snow. Preliminary results obtained from Greenland (NEEM) snow pit samples confirm its applicability in environmental research