REE profiling in basic volcanic rocks after ultrasonic sample treatment and ICPMS analysis with oxide ion formation in ICP enriched with O2

•REEs were determined in soils and sediments after ultrasound assisted acid digestion by ICPMS.•An Ar-O2 ICP was used to convert REEs into MO+ ions enabling its determination at m/z + 16.•Algebraic correction were applied to correct for isobaric overlaps.•REEs, Sc and Y could be successfully determined with adequate sensitivity in environmental samples.

ICP-MS methods, and its variants, had been extensively used to determine REEs due to their lower detection limits, high sensitivity and dynamic linear range. However, spectral interferences caused by oxide and hydroxide ions always represents an issue regardless the type of sample been dealt. In the present work it was described the study of REEs oxides formation with the introduction of an auxiliary line directly to the cyclonic chamber to generate a mix Ar/O2 plasma. Plasma conditions were optimized by studying and selecting the best flow rates to induce the formation of REEs oxides. A new analytical method for REE determination was thus proposed using ICPMS with Ar-O2 mixed plasma to aid the formation of MO ions. This method was validated through CRM analysis and through the analysis of real-world samples. The REE concentrations evaluated and normalized to chondrite REE levels allowed the analysis of basaltic rocks study in terms of their origin.