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Issue 12, 2003
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Suppression of Zr, Nb, Hf and Ta coprecipitation in fluoride compounds for determination in Ca-rich materials

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Abstract

We have evaluated recovery yields of Zr, Nb, Hf and Ta, which are called high field strength elements (HFSE), in the synthetic Ca–Al–Mg–HF solution system using two different methods: at <70 °C in an ultrasonic-bath (denoted as the ultrasonic method) and at 205 °C using a TFE Teflon® bomb (denoted as the bomb method). Full recovery of HFSE into the supernatant HF solution was not achieved in cases where fluorite (CaF2) forms in the precipitate in both methods and sellaite (MgF2) forms in the ultrasonic method. In order to suppress fluorite precipitation, an ‘Al-addition method’ was developed in which Al solution is added to the sample before decomposition to change the matrix solution to a composition in which no fluorite forms. Using the Al-addition method, HFSE concentrations of Ca-rich materials were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) by an isotope dilution method for Zr and Hf and by a calibration curve method for Nb and Ta. Furthermore, we found isotopic disequilibria of Zr and Hf between sample and spike without Al-addition for Ca-rich samples, and that the Al-addition method was very effective in achieving isotopic equilibria and full recovery of HFSE, resulting in high accuracy in their determination.

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Publication details

The article was received on 18 Aug 2003, accepted on 03 Oct 2003 and first published on 24 Oct 2003


Article type: Paper
DOI: 10.1039/B309948B
Citation: J. Anal. At. Spectrom., 2003,18, 1458-1463
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    Suppression of Zr, Nb, Hf and Ta coprecipitation in fluoride compounds for determination in Ca-rich materials

    R. Tanaka, A. Makishima, H. Kitagawa and E. Nakamura, J. Anal. At. Spectrom., 2003, 18, 1458
    DOI: 10.1039/B309948B

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