A rapid, accurate and less labor intensive approach to determining ²²⁶Ra in environmental samples was examined; this utilized quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS). The procedure used chemical separation by ion exchange chromatography to remove most of the matrices after coprecipitation with BaSO₄. The average chemical recovery of the NIST SRM preparation method ranged from 60.5 to 85.9% using ¹³³Ba as internal tracer by gamma counting. This technique was capable of completing a ²²⁶Ra measurement within 3 min. It did not require an in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent ²²⁶Ra as is needed for liquid scintillation analyzer (LSA). The method detection limits for the determination of ²²⁶Ra in geothermal water and sediment samples were 0.02 mBq L⁻¹ (0.558 fg L⁻¹ ) and 0.10 Bq kg⁻¹ (2.79 fg g⁻¹ ), respectively. The results obtained with various natural samples and the suitability of the method when applied to various environmental matrices such as geothermal water and sediment are discussed. When ICP-QMS was compared to double-focusing magnetic sector field inductively coupled plasma mass spectrometry (ICP-SFMS), good agreement was obtained with a correlation coefficient, r² = 0.982.
關聯:
Journal of Radioanalytical and Nuclear Chemistry vol. 286, no. 1 pp.145-154
