Determination of traces of uranium and thorium in (Ba, Sr) TiO3 ferroelectrics by inductively coupled plasma mass spectrometry
1997
Fukuda, M. | Sayama, Yasumasa
Traces of uranium and thorium in barium(II), strontium(II) titanate ((Ba, Sr)TiO₃) ferroelectric materials were determined by inductively coupled plasma mass spectrometry (ICP-MS). Samples were completely dissolved by a mixture of 1.4% H₂O₂ and 1.0 mol⋅l⁻¹ HNO₃. For a complete separation of the analytes from the matrix elements, a two step separation technique involving leaching and anion-exchange was applied. By the leaching step with HNO₃ more than 90% of the matrix can be removed whereas the analytes completely remained in the solution. The anion-exchange step was carried out on a BIO⋅RAD AG1-X8 column with a mixture of 1.0 mol⋅l⁻¹ HF and 0.5 mol⋅l⁻¹ HNO₃ as eluent. The content of uranium and thorium was subsequently measured by ICP-MS. The detection limits (D.L.) obtained were 0.043 ng g⁻¹ and 0.035 ng g⁻¹ for U and Th, respectively. The reproducibility was satisfactory with a relative standard deviation of less than 3% (at the 1 ng g⁻¹ level, n=5). The matrix concentrations in the final solution were reduced to the sub-μg ml⁻¹ level which is in the range of the detection limits of USN-ICP-AES (ultrasonic nebulization-ICP-atomic emission spectroscopy). The method was successfully applied to the determination of uranium and thorium in three synthetic (Ba, Sr)TiO₃ samples spiked with the analytes at levels of 1, 5 and 10 ng g⁻¹ and three (Ba, Sr)TiO₃ ferroelectric samples containing sub-ng g⁻¹ levels of the analytes.
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