HPLC combined with ICP-MS for the determination of trace amounts of rare earth impurities in high-purity La2O3 by using 2-ethylhexyl hydrogen-2-ethylhexylphosphonate resin as a stationary phase

A new method for the determination of trace rare earth impurities in high-p urity La2O3 by HPLC combined with ICP-MS is proposed. The chromatographic r etention behavior of La and Ce in HPLC was studied with 2-ethylhexyl-hydrog en-2-ethylhexylphosphonate (P507) resin as the stationary phase and inorgan ic acid (HNO3) as the mobile phase. The effects of acidity of the mobile ph ase, flow rate of eluent and column oven temperature on the separation of L a and Ce were investigated in detail. The results of the effect of differen t ratios of La/Ce showed that a favorable separation of La and Ce could be obtained easily and rapidly with the method presented. Compared with the co nventional open column method, the proposed separation system shows a good performance with regard to short separation time, low reagent consumption, and simple operation. The method has been applied to the analysis of real s amples of high-purity La2O3 with satisfactory results.