Preconcentration of Rare Earth Elements Using Amberlite XAD-4 Modified With 2,6-Pyridinedicarboxaldehyde and Their Determination by Inductively Coupled Plasma Optical Emission Spectrometry

Abstract

A new solid phase extraction method was developed for the preconcentration and determination of rare earth elements (REEs) (Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu, Ce) in water samples. The method is based on the sorption of REE ions onto the 2,6-pyridinedicarboxaldehyde-functionalized Amberlite XAD-4 resin at pH 7.0, followed by the elution with 2 mL of 1.0 mol L−1 HNO3 solution and determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The main parameters affecting preconcentration, including sample pH, sample and eluent flow rate, and sample volume, have been investigated in detail. Under the optimum conditions (pH 7.0, sample flow rate of 1.0 mL min−1, and eluent flow rate of 4.0 mL min−1), detection limits between 0.011 and 0.298 μg L−1 for a 25 mL sample volume and 0.006 and 0.149 μg L−1 for a 50 mL sample volume were obtained. The sorption capacities for the resin were found to range between 49.0 μmol g−1 (for Lu) and 66.7 μmol g−1 (for Sm). The method was validated by analysis using a surface water certified reference material (SPS-SW2 Batch 127). The proposed method was successfully applied to the determination of REEs in tap water and seawater samples. The recovery values for the spiked water samples were in the range of 90.0–101.7 %.