Determination of rare earths in standard reference material glass using neutron activation analysis and reversed-phase chromatography

Abstract

Recently, the interest in quantitative determination of rare earth elements has grown considerably, especially in connection with the space programs. There has also been a need for quantitative methods for rare earth element determination in different matrices at the National Bureau of Standards. We have therefore applied some of our earlier qualitative investigations with di(2-ethylhexyl) orthophosphoric acid (HDEHP) to separations of these elements for their subsequent quantitative determination. The rare earth elements in NBS Standard Reference Material 480, Trace Elements in Glass, a sodium glass to which 61 trace elements, including the thirteen naturally occurring rare earths, were added, have been determined by neutron activation analysis with a chemical separation using a column (11 cm×40 cm) of “Corvic” powder [poly(vinyl chloride-vinyl acetate)] loaded with HDEHP and operated at a constant temperature. Since our earlier solvent extraction studies with HDEHP had shown perchloric acid to be the most favorable of three acids (HCl, HNO₃, HClO₄) for rare earth separation, we established the best operating conditions (e. g. time, flow, acid concentration, etc.) using this acid. A detailed description of the separations procedure and the quantitative results will be discussed.