Determination of rare earth elements by ion chromatography. Separation procedure optimization

In the development of research on materials for optical fibres production, the use of pure lanthanum compounds is very important for the manufacture of glasses, since they can play an important role for signal enhancement by fluorescence emission. For this purpose, an ion exchange chromatographic method for rare earth determination has been studied and optimized. The analytical column involved was a multimode ion exchange type and the effectiveness of ligands (namely oxalic and diglycolic acids) on lanthanides elution was investigated. Elutions were performed for iigand concentrations ranging from 0 to 80 mM and pH ranges from 3.0 to 5.5 coupled with a post-column spectrophotometric detection with 4-(2-pyridylazo)resorcinol (PAR) at 520 nm. After optimization, gradient elution enabled the determination of lanthanides with in a total analysis time of 25 min. The method developed has been applied to the analysis of YbF3 (after acidic microwave digestion) for the determination of impurities due to other rare earth elements.