Preconcentration of uranium(VI) by solid phase extraction onto dicyclohexano-18-crown-6 embedded benzophenone

The preparation of a solid phase extractant (SPE), dicyclohexano-18-crown-6 embedded benzophenone, for preconcentration of uranium(VI) is described. The uranium(VI) can be quantitatively retained from 0.5 l solution on 1% dicyclohexano-18-crown-6 embedded benzophenone in the pH range 6.0-7.0, and then eluted with 5.0 ml of 1M HCl. Uranium(VI) content of the eluent was determined spectrophotometrically by Arsenazo III. Calibration graphs are rectilinear over the uranium(VI) concentration in the range of 0.004-0.4 mu g(.)mg(-1). Five replicate determinations of 40mg of uranium(VI) present in 0.51 sample gave a mean absorbance of 0.185 with a relative standard deviation of 2.45%. The detection limit corresponding to three times the standard deviation of the blank was found to be 2.0 mu g(.)l(-1). The accuracy of the developed preconcentration procedure was tested by analyzing standard marine sediment reference material. The uranyl ion content of soils and sediments was estimated spectrophotometrically after the preconcentration procedure and compared to the results gained by standard inductively coupled plasma mass spectrometry (ICP-MS).