Preconcentration and elimination of matrix effects in XRF determinations of rare earth elements by preparing a thin film through chemofiltration

Trace rare earth elements (REE) can be enriched by collecting them on a filter after they have formed their complexes with 2,2'-(1,8-dihydroxy-3,6-disulfonaphthylene-2,7-bisazo) bisbenzenearsonic acid (Arsenazo III) through a process called chemofiltration. The filter, which constitutes a thin film, is passed directly to the X-ray fluorescence (XRF) spectrometer, eliminating, in this manner, the interelemental effects produced in XRF determinations. High preconcentration factors and low detection limits are obtained: 18.3 ng mL(-1) for Sm, 17.5 ng mL(-1) for Eu and 34 ng mL(-1) for Gd. The method was applied to the determination of these elements in NIST standard reference glasses with very good precision.