Adaptation of ICP-OES routine determination techniques for the analysis of rare earth elements by chromatographic separation in geologic materials: tests with reference materials and granitic rocks

The present contribution shows the results of tests on geological materials for determination of the rare-earth elements La, Cc, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Y and Sc. The samples were prepared using lithium borate fusion of powdered rock sample followed by dissolution in hydrochloric acid. A separation was performed in cationic exchange columns with resin by hydrochloric and nitric acid gradient concentration and subsequent analysis using inductively coupled plasma atomic emission spectrometry (ICP-OES) and an ultrasonic nebulizer. All potentially interfering elements, except Ba and Zr, were eliminated using this procedure. Spectral interferences generated by Zr and the REE among themselves (Ce on Gd, Nd on Sm-Ce-Er, Gd on Sm, Pr on La-Ce-Nd-Ho-Tb, Tb on Ho, Sm on Tb) were identified and corrected quantitatively. The whole procedure was tested with international geological standard reference materials AGE and JG-3 (granitic rocks), JB-1a (basalt), JA-2 (andesite), JR-2 (rhyolite) and JGb-1 (gabbro). A Student's statistical test showed that the obtained analytical results were mostly satisfactory. The methodology, now performed on a routine basis, was applied for the determination of the REE patterns of assorted granitic rocks occurring in the state of Sao Paulo, southeastern Brazil. (C) 2002 Elsevier Science B.V. All rights reserved.