Solid phase extractive preconcentration of uranium on to 5,7-dichloroquinoline-8-ol modified naphthalene

The preparation of solid reagent, (5,7-dichloroquinoline-8-ol) modified naphthalene for preconcentration of uranium is described. The uranium-5,7-dichloroquinoline-8-ol complex is quantitatively retained on naphthalene in the pH range 4.5-7.0. For the preconcentration of uranium an aliquot or the above reagent is added to the uranium sample solution, adjusted to pH 5.5 +/- 1.0 and the residue is filtered off and dissolved in acetone for analysis by the arsenazoIII method. Calibration graphs are linear over the uranium concentration range 2-100 mug per 5 ml of final solution. Ten replicate determinations of 40 mug of uranium present in one liter of sample gave a mean absorbance of 0.185 with a relative standard deviation of 1.5%. The detection limit corresponding to 3 times the standard deviation of the blank was found to be 2 ng/ml. The validation of the developed preconcentration procedure was carried out by successfully analysing standard marine sediment reference material.