Pre-concentration, separation and trace determination of lanthanum(III), cerium(III), thorium(IV) and uranium(VI) on polymer supported o-vanillinsemicarbazone

A nonionic polymeric adsorbent styrene divinylbenzene, Amberlite XAD-4 was functionalized with o-vanillinsemicarbazone and its analytical properties have been studied. The synthesized resin was utilized for selective column separation, pre-concentration and trace determination of lanthanum(III) (La(III)), cerium(III) (Ce(III)), thorium(IV) (Th(III)) and uranium(VI) (U(VI)). The resin exhibits good chemical stability, reusability and faster rate of equilibrium for their determination by spectrophotometry and their simultaneous confirmation of the results by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and graphite furnace-atomic absorption spectrometry (GF-AAS). Both, the uptake and stripping of these metal ions were fairly rapid, indicating a better accessibility of the chelating sites. The proposed method has been applied to sequential chromatographic separation of their binary and ternary mixtures. Uranium(VI) has been determined from simulated river water sample with good analytical reliability. The detection limit of these metal ions on the resin is 100 ng cm(-3) with recovery upto 96-98%. The method is also applied for their determination in monazite sand and some standard geological materials. (C) 2001 Published by Elsevier Science B.V.