Europium preconcentration by filtration of ternary complexes prior their determination by XRF spectrometry

Abstract

The detection of trace rare earths in diverse materials and the importance of their determination have led to the search for different preconcentration methods for their quantification through instrumental analysis. The preconcentration method for Eu proposed here is based in the formation of a ternary complex with 1,8-dihydroxy-2-[4-sulfophenylazo]-naphthalen-3,6-disulfonic acid (SPADNS) and a surfactant agent. The complex is collected on a nitrocellulose filter, obtaining a thin film. The Eu complex retained on the membrane is measured by X-ray fluorescence spectrometry. The development of the preconcentration methodology implied the study and optimisation of the ternary complex formation in terms of pH, surfactant agent, reagent concentration, etc. The preconcentration factor was 2 × 10⁴ and the lower detection limit for the preconcentration of 25 mL of aqueous solution was 22 ng mL⁻¹. The method was successfully applied to the determination of Eu in synthetic host material.