Determination of 129I 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 129I 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® AS16 column to retain iodine species in the absence of NaOH has been used to pre-concentrate 5 mL samples. Although 129I suffers from isobaric spectral interference due to the presence of 129Xe, the IC-ICP-SFMS technique allows 129I to be determined by removing all other isobaric interferents. Furthermore, the 129Xe interference is sufficiently small and stable to be treated as a background correction. This strategy permits the evaluation of 129I 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.