HPLC separation of La, Th and U using modified C18 reversed phase column

High performance liquid chromatography (HPLC) is a versatile technique used for the separation of lanthanides and actinides in the field of nuclear industry. Hydroxycarboxylic acid based ligands such as α-hydroxyisobutyric acid (HIBA) is extensively used eluent for the separation of lanthanides and actinides. The difference in binding nature of lanthanides and actinides is being explored for their separation. However, challenges are encountered when one of the elements is present in the large excess. e.g. The separation of minor lanthanides in a dysprosium matrix is challenging due to the presence of trivalent interfering ions. It was observed that in case of hydroxycarboxylic acid based ligands, the sample acidity need to be optimized in HPLC and this may cause the precipitation of the major matrix. In order to circumvent these problems, chelation chromatography with different extractive reagents has been explored by researchers. In the current paper, we have investigated N, N, N, 'N'-tetraoctyl di-glycolami de-coated reversed phase C18 column for the separation of La, Th and U. The parameters such as amount and composition of the modified solution containing N, N, N, 'N'-tetraoctyldiglycolamide were optimised. Studies were also carried with respect to optimization of the parameters related to the sample mixture, such as acidity, NaNO₃ concentration etc. Under the optimized condition the separation of La (50 ppm), Th (50 ppm) and U (5000 ppm) were carried out at acidity of 1M HNO₃