Determination of uranium in natural waters after anion-exchange separation

A method is described for the determination of uranium by fluorimetry and spectrophotometry in samples of natural non-saline waters. After acidification with hydrochloric acid, the water sample is filtered and, following the addition of ascorbic acid and potassium thiocyanate, passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (thiocyanate form). On this exchanger uranium is adsorbed as an anionic thiocyanate complex. After removal of iron and other coadsorbed elements by washing first with a mixture consisting of 50 vol.% tetrahydrofuran, 40 vol.% methyl glycol and 10 vol.% 6 M hydrochloric acid, and then with pure aqueous 6 M hydrochloric acid, the uranium is eluted with 1 M hydrochloric acid. In the eluate, uranium is determined fluorimetrically or by means of the spectrophotometric arsenazo III method. The procedure was used for the routine determination of uranium in water samples collected in Austria.