DETERMINATION OF URANIUM BY CUPFERRON WITH COMPLEXONE III AS THE MASKING AGENT LY A. I<. MAJUMDAI< ,\sn J. IS. RAY CHOWI)HUlIY JuduvpY Unlvcrslly. Cak1rllu (IdlU)
In previous communications dealing with complexone III as a masking agent and cupfcrron as ;L precipitant it was shown tliat both tctra-and hexavalcnt uranium interfere in the determination of titanium' and niobium 2. 'Thcrcforc it was considered worthwhile to study the applicability of cupfcrron as a reagent for hexavalent uranium. This reagent was previously used for the precipitation of tetravalent uranium from an acid solution3.
From a solution maintained at a PII between G and 7 by ammonium acetate-acetic acid buffer, hcxavalcnt uranium is scparatcd by the reagent from the followingions: copper, bismuth, ferric, chromium, thorium, aluminium, molybclate, vanaclate and tungstatc, which arc kept in solution by complcxone III. The ions of cadmium, lead, zinc, manganese, nickel, cobalt, rare earths, alkalis and alkaline earths have no effect but the ions of titanium, beryllium, tin (stannous and stannic), antimony, arsenic and phosphate interfere. l'hc uranium -cupfcrron complex like other metalcupfcrron complexes can be ignited to oxide before weighing. A DETERMINATION OF u WITH COMPLEXONE-1x1 577 A large excess (about to-15 times) of complcxonc III was added to a solution containing uranyl nitrate, either alone or admixed with other ions from whicll It has to lx separated. The pH of the solution was then adjust4 to 6-7 by the aclclition of a zoo<, ammonium acotatc solution. The solution was then Muted to 250-300 ml, cooled to about loo and mixad with the reagent solution added dropwlsc under vigorous stn-rmg till the prccipltation was complctc. The prccipitatc was then filtered, washccl with colcl wash water containing a little cupferron, clricd, ignited to 1J30, and welghcd (cf. Tahlc I). SUMMARY At a pH hetwccn 4 and 6, hcxavalent uranium IS quantitatively prccipitatcd by cupfcrron in the prcscncc of complcxonc III and thus can bc scpnratcd from Bif3,