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Coral 129I/127I measurement method using ICP-MS and AMS with carrier addition

Abstract

Iodine-129 in coral cores provide historical records of human nuclear activities, establish or confirm coral age models, and trace environmental processes. During the time of this writing, the only published method (Biddulph et al., 2006) for measuring 129I/127(stable)I in corals requires 10-30g of sample, which can be too large for common practice. To reduce this sample size requirement, we modified the existing method in two aspects: (1) we used inductively coupled plasma mass spectrometry (ICP-MS) instead of iodide selective electrode (ISE) for stable 127I measurement; and (2) we added 0.66 mg of low-ratio (129I/127I = 1.5 x 10-14) iodine carrier instead of using carrier-free method for target preparation for 129I measurement by accelerator mass spectrometry. For 127I measurement, we obtained detection limit and limit of quantitation of 0.089 and 0.27 ppb, respectively, using 133Cs internal standard, 286x dilution factor, and drift correction. Average 127I concentration in corals was 4.5 ppm. For 129I/127I measurement, we determined average anthropogenic (post-1950) and natural (pre-1950) ratios of 20 x 10-12 and 1.4 x 10-12, respectively, in our coral samples. In addition, average relative standard deviations were 11.5% and 23% for anthropogenic- and natural-age coral samples, respectively. Our method successfully measured 129I/127I in 1-4 g of corals with accuracy and precision comparable to the existing method, which required 10-30 g of corals.

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Publication details

The article was received on 12 Jun 2017, accepted on 08 Aug 2017 and first published on 09 Aug 2017


Article type: Paper
DOI: 10.1039/C7AY01458A
Citation: Anal. Methods, 2017, Accepted Manuscript
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    Coral 129I/127I measurement method using ICP-MS and AMS with carrier addition

    A. T., V. Bautista, Y. Miyake, H. Matsuzaki and F. P. Siringan, Anal. Methods, 2017, Accepted Manuscript , DOI: 10.1039/C7AY01458A

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