Evaluation of signal-to-background and Mg II/Mg I ratios as response for the optimization of rare earth elements determination by inductively coupled plasma optical emission spectrometry

Abstract

Rare earth elements (REEs) is a peculiar group of chemical elements. Their determination in geological samples is important and complex due to their low concentrations and problems with spectral and non-spectral interferences. Herein, the operating conditions of an inductively coupled plasma optical emission spectrometer were optimized for the determination of REEs using experimental designs. The signal-to-background ratio (SBR) of the REEs emission signals and the Mg II/Mg I line intensity ratio were evaluated as response functions. According to the results obtained, three different sets of operating conditions were selected and classified as robust, semi-robust and best SBR conditions. Limits of detection (LOD), SBR and relative standard deviation of the blank solution (RSDblank) were determined. The semi-robust condition (RF power of 1250 W and nebulizer gas flow rate of 0.90 L min -1) exhibited lower LOD and RSDblank than others tested operating conditions. © 2012 Sociedade Brasileira de Química.