A simple separation system for elimination of molecular interferences for purity determination of europium and ytterbium oxides by HPLC-ICP-MS

• Published in: Journal of analytical atomic spectrometry 2020-11, Vol.35 (11), p.2594-2599
• Main Authors: Nguyen, Viet Hung, Ramzan, Muhammad, Kifle, Dejene, Wibetoe, Grethe
• Format: Article
• Language: English
• Subjects: Coupling (molecular); Europium; Europium compounds; High performance liquid chromatography; Inductively coupled plasma mass spectrometry; Oxides; Phosphonic acids; Purity; Separation; Silicon dioxide; Trace impurities; Ytterbium
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/d0ja00246a

A simple and rapid HPLC-ICP-MS method for determination of ultra-trace REE impurities in highly pure Eu 2 O 3 and Yb 2 O 3 has been developed. The majority of REEs as trace impurities in both Eu 2 O 3 and Yb 2 O 3 matrices can be determined solely by ICP-MS. However, 153 Eu 16 O + and 174 YbH + formed in the plasma of the ICP-MS overlap with the monoisotopic 169 Tm + and the most abundant isotope of Lu ( 175 Lu + ), respectively. Spectral interferences caused by the formation of matrix-based polyatomic ions are eliminated by separating the highly concentrated matrix element from the spectrally interfering elements of interest. This is achieved by coupling HPLC to ICP-MS. A reversed-phase C-18-silica HPLC column impregnated with 2-ethylhexyl, 2-ethylhexyl phosphonic acid (H[EH(EHP)]) is prepared and used as a separation tool. The method allows separation of problematic REEs, viz Eu from Tm and Yb from Lu in time and space prior to entering the ICP-MS, which enables accurate determination of the REEs in question. The method is used to characterize high purity Eu 2 O 3 and Yb 2 O 3 through the impurity approach, focusing on trace concentrations of other REEs in the respective oxides. The method is rapid with a separation time of 3.5 minutes, which makes it suitable for routine analysis of trace levels of all REE impurities, including Tm and Lu in high-purity europium and ytterbium oxides. The chromatographic system is compatible with ICP-MS as the mobile phase consists only of diluted HNO 3 . A simple and rapid HPLC-ICP-MS method for determination of ultra-trace REE impurities in highly pure Eu 2 O 3 and Yb 2 O 3 has been developed.