Mini-Scale Solid-Phase Collection and Concentration of Ultra-Trace Elements in Natural Waters for the Simultaneous Multielement Determination by Air-Flow Injection/ ICP-Mass Spectrometry

A mini-scale solid-phase collection and concentration method for the multielement determination of ultra-trace rare earth elements (REEs) in natural water samples was developed by using a newly designed small-scale filtration apparatus. A small-size chelating resin disk (iminodiacetate type: IDA; 10 µm pore size; 5 mm diameter; 0.5 mm thickness) was used for high-enrichment preconcentration of REEs and for elimination of alkali and alkaline earth metals in sample solutions. At pH 5.5, REEs in artificial river waters were quantitatively collected on the chelating resin disk, and most of alkali and alkaline earth metals were removed. The REEs on the chelating resin disk were completely recovered by ultrasonication of the disk with 1 cm3 or less of 0.1 mol dm−3 nitric acid. A small amount (25 µL) of the concentrated sample solution was automatically injected and measured by inductively coupled plasma – mass spectrometry (ICP–MS) coupled with an air flow injection (AFI) system.