Ion chromatographic separation of rare-earth elements using a nitrilotriacetate-type chelating resin as the stationary phase

The chromatographic retention behavior of rare-earth elements (REEs) on a chelating resin having a nitrilotriacetate group (NTA gel) was evaluated. The capacity factors for a series of REEs on the NTA gel were in fairly good agreement (R(2) = 0.978) with the stability constants of the corresponding NTA complexes. The NTA gel was applied to the column stationary phase for the ion chromatographic separation of REE. A favorable separation of a series of REEs was achieved within 15 min using a gradient elution of nitric acid. The separated REE ions were detected using the postcolumn derivatization method with chlorophosphonazo III as a colorization reagent. The present chromatographic system, interfaced with inductively coupled plasma mass spectrometry, was applied for the simultaneous determination of 14 REEs.