Determination of trace rare earth impurities in high-purity cerium oxide by using electrothermal vaporization ICP-AES after HPLC separation with 2-ethylhexylhydrogen 2-ethylhexylphosphonate resin as the stationary phase

A method is proposed to determine trace rare earth impurities in high-purity CeO2 by HPLC combined with electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES). The chromatographic retention behaviours of the matrix (Ce) and rare earth impurities were studied using 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (P507) resin as the stationary phase and dilute nitric acid as the mobile phase. It was found that the matrix (Ce) can be separated quantitatively with dilute nitric acid as the mobile phase, and the rare earth impurities (Pr-Lu) can be eluted effectively by use of EDTA as an eluent. The experimental results show that a favorable separation between the matrix (Ce) and rare earth impurities (Pr-Lu) can be obtained within 60 min. The method proposed has been applied to determine 14 rare earth impurities in high-purity CeO2 with satisfactory results.