On-line preconcentration and vapor generation of scandium prior to ICP-OES detection

Abstract

A novel on-line scandium preconcentration system implemented with chemical vapor generation associated to inductively coupled plasma optical emission spectrometry (VG-ICP-OES) was studied. The variables involving the preconcentration and the vapor generation were optimized using both full factorial and central composite designs, respectively. Trace amounts of scandium were preconcentrated by sorption on a minicolumn packed with activated carbon (AC) at pH 7.0. The analyte retained was removed from the minicolumn with 10% (v/v) hydrochloric acid. After that, volatile species of scandium were generated by merging the acidified sample and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the inductively coupled plasma torch. For the preconcentration/vapor generation procedure, an enhancement factor of 240-fold (10 for VG with respect to the traditional pneumatic nebulization and 24 for preconcentration) for a sample volume of 25 ml was obtained. The detection limit (DL) obtained was 4.0 μg l⁻¹. The precision (RSD) for ten replicate determinations at a level of 100 μg l⁻¹ was 4.0%. Potential interfering effects on the Sc signal were examined. The methodology was applied to the determination of scandium in river water samples.