Determination of rare-earth elements by high-performance liquid chromatography/inductively-coupled plasma/atomic emission spectrometry

Liquid chromatography coupled on-line to a sequential ICP/AES system is applied for the determination of 14 rare-earth elements (REEs) in samples with widely different concentrations of REEs and matrix elements. The REEs are separated on a cation-exchanger by applying an α- hydroxyisobutyric acid gradient. The determination limits were the same as those obtained by continuous nebulization of single-element standard solutions. The chromatographic separation precludes mutual spectral interferences between the REEs. The practical value of the method developed is demonstrated by the determination of REE impurities in Specpure rare-earth oxides, by its demonstrated potential to evaluate real spectral interferences, and by the analysis of geological samples (natural phosphates) with relatively low total REE contents. The detection limits of REEs in these natural phosphates ranged between 0.005 and 0.4 μg g^?1.