Analytical Sciences

Application of NOBIAS Chelate-PA 1 Resin to the Determination of Zirconium, Niobium, Hafnium, and Tantalum in Seawater

Yuriko TANAKA, Makoto TSUJISAKA, Linjie ZHENG, Shotaro TAKANO, and Yoshiki SOHRIN

Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan

Zirconium, niobium, hafnium, and tantalum are dissolved in seawater as hydroxide complexes at a concentration as low as 0.01 – 370 pmol kg⁻¹ and are expected to be potential tracers for water masses in the ocean. Herein, we report a new analytical method for the multielemental determination of the four elements on the basis of column extraction, using a NOBIAS Chelate-PA 1 resin that contains ethylenediaminetriacetic acid groups. The elements were collected on the resin from seawater that had been added with 3.8 mM HF at pH 6.0, and were eluted with 5 M HF. After the evaporation of 5 M HF, the elements were dissolved in 0.5 M HNO₃–6 mM H₂SO₄–1 mM HF and were determined by a high resolution ICP-MS, using a calibration curve method. We optimized the procedure to achieve quantitative recoveries and low backgrounds for the elements, although the complex formation between the metal ions and NOBIAS Chelate-PA 1 was decelerated by the seawater matrix. The method was tested by investigating the seawater samples of reference material and those collected from the depths at a station in the western North Pacific Ocean.

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