Development of a separation method for uranium isotopic mass ratio measurement in environmental samples by ICP-MS

A separation method using TEVA Spec resin (Eichrom Industries Inc.) was studied for a simple and rapid measurement of uranium mass ratio in environmental soil samples by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). The resin, charged in a minicolumn, retained U from a 20-mL sample solution adjusted to 6 M HCl. After washing the column with 6 m HCl, U was eluted with 20 mL of 1 M HCl. Through this separation process, U in a standard solution was purified from major and minor elements including Fe. Subsequently, the method was also applied to actual soil sample solutions, but U could not be separated from Fe. This was possibly attributed to Fe contents in the samples being higher than in that in the standard solution, and Fe would affect U sorption onto the resin. However, the separation method could separate U from major matrix elements in soil and the isotopic mass ratios of ²³⁵U/²³⁸U and ²³⁴U/²³⁸U could be measured by Q-ICP-MS using a 0.1 g sample of dried soil. (author)