Determination of element/Ca ratios in foraminifera and corals using cold- and hot-plasma techniques in inductively coupled plasma sector field mass spectrometry

Li Lo, Chuan Chou Shen*, Chia Jung Lu, Yi Chi Chen, Ching Chih Chang, Kuo Yen Wei, Dingchuang Qu, Michael K. Gagan

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)

    Abstract

    We have developed a rapid and precise procedure for measuring multiple elements in foraminifera and corals by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS) with both cold- [800W radio frequency (RF) power] and hot- (1200W RF power) plasma techniques. Our quality control program includes careful subsampling protocols, contamination-free workbench spaces, and refined plastic-ware cleaning process. Element/Ca ratios are calculated directly from ion beam intensities of 24Mg, 27Al, 43Ca, 55Mn, 57Fe, 86Sr, and 138Ba, using a standard bracketing method. A routine measurement time is 3-5min per dissolved sample. The matrix effects of nitric acid, and Ca and Sr levels, are carefully quantified and overcome. There is no significant difference between data determined by cold- and hot-plasma methods, but the techniques have different advantages. The cold-plasma technique offers a more stable plasma condition and better reproducibility for ppm-level elements. Long-term 2-sigma relative standard deviations (2-RSD) for repeat measurements of an in-house coral standard are 0.32% for Mg/Ca and 0.43% for Sr/Ca by cold-plasma ICP-SF-MS, and 0.69% for Mg/Ca and 0.51% for Sr/Ca by hot-plasma ICP-SF-MS. The higher sensitivity and enhanced measurement precision of the hot-plasma procedure yields 2-RSD precision for μmol/mol trace elements of 0.60% (Mg/Ca), 9.9% (Al/Ca), 0.68% (Mn/Ca), 2.7% (Fe/Ca), 0.50% (Sr/Ca), and 0.84% (Ba/Ca) for an in-house foraminiferal standard. Our refined ICP-SF-MS technique, which has the advantages of small sample size (2-4μg carbonate consumed) and fast sample throughput (5-8samples/hour), should open the way to the production of high precision and high resolution geochemical records for natural carbonate materials.

    Original languageEnglish
    Pages (from-to)115-122
    Number of pages8
    JournalJournal of Asian Earth Sciences
    Volume81
    DOIs
    Publication statusPublished - 5 Feb 2014

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