title: Group separation of trace rare-earth elements by countercurrent chromatography for their determination in high-purity calcium chloride.
abstract: A method has been developed for the separation of the entire group of rare-earth elements from high-purity calcium chloride by countercurrent chromatography, and subsequent determination of the elements by ICP-MS. A solution of diphenyl[dibutylcarbamoylmethyl]phosphine oxide in chloroform (0.5 mol L(-1)) has been chosen as reagent for the extraction and preconcentration of trace rare-earth elements from aqueous 5% CaCl2 solution, 3 mol L(-1) in HNO3 and 0.1 mol L(-1) in HClO4. The analytes are back-extracted into a small volume of water and the aqueous eluate is subjected to ICP-MS measurements. The performance characteristics of the procedure developed have been checked by use of the standard addition technique and a real CaCl2 sample (Merck product) has been analyzed. The results obtained demonstrate the applicability of countercurrent chromatography to the determination of ultratrace elements.
authors.affiliation: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow.
authors.forename: S N
authors.initials: SN
authors.lastname: Ignatova
authors.forename: T A
authors.initials: TA
authors.lastname: Maryutina
authors.lastname: Spivakov BYa
authors.forename: V K
authors.initials: VK
authors.lastname: Karandashev