X-Ray Fluorescence Analysis of Individual Rare Earths in Complex Minerals

A combined chemical x-ray fluorescence method is described for determining rare-earth elements in small amounts of complex rare-earth minerals. These elements yield a complex x-ray spectrum in which many of the analytical emission L α lines of a given element coincide with the L β and/or L γ lines of a lighter rare-earth element several atomic numbers removed. The proposed analytical scheme corrects for these interferences. Sixteen elements consisting of the lanthanides, yttrium, and scandium can be determined on as little as a 1-mg portion of the separated oxides. The oxides are dissolved in 1 ml of dilute acid, absorbed onto cellulose powder and pressed into a pellet for x-ray excitation. Chemically analyzed geologic standards are not required for calibration.