Analytical Sciences

Determination of Ultratrace Impurities in High Purity Tantalum Materials by On-line Anion Exchange Matrix Separation and Inductively Coupled Plasma Mass Spectrometry

Shuji KOZONO,* Ryuma TAKASHI,* and Hiroki HARAGUCHI**

*Analysis and Physical Properties Center, SHOWA DENKO K. K., Ohnodai 1-1-1, Midori, Chiba 267-0056, Japan
**Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan

Ultratrace metal impurities (Be, Al, Ti, Cr, Ni, Nb, Mo, Sn, W, Th, and U) in high purity tantalum metal, tantalum(V) oxide, and tantalum pentaethoxide were determined by a combined system of flow injection with an anion exchange column and inductively coupled plasma mass spectrometry (ICP-MS). In the present combined system, the on-line matrix separation and multielement determination of impurity elements could be performed. When 2 M HCl/0.1 M HF mixed solution and 1 M HNO₃/0.1 M HF mixed solution were used as the carrier solutions, Be, Al, and Ti for the former, and Cr, Ni, Nb, Mo, Sn, W, Th, and U for the latter were eluted from the column without any tantalum matrix. The detection limits (3 sigma) of analyte elements were in the range over 0.003 - 0.14 ng/ml as the sample solution basis. The present method was applied to the determination of metal impurities in high purity tantalum materials. The concentrations of Be, Ti, Mo, Sn, Th, and U were at the ng/g level, while those of other elements were in the range over the µg/g - ng/g level.

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