AS 2723-1984

Sets out a spectrophotometric method for the determination of uranium (VI) in both fresh waters, in the concentration range 0.12 mg/L to 16 mg/L and saline waters in the range 0.3 mg/L to 40 mg/L. A preliminary chelating resin separation extends the application of the method of polluted and waste waters for the uranium (VI) concentration range 0.12 mg/L to 16 mg/L.

This standard sets out a spectrophotometric method for the determination of filtrable uranium(VI) in waters.The method is directly applicable to fresh waters with uranium(VI) in the range 0.12 mg/L to 16 mg/Land to saline waters and seawater with uranium(VI) in the range 0.3 mg/L to 40 mg/L.A preliminary chelating resin separation is applicable to polluted waters and waste waters with uranium(VI) in the range 0.12 mg/L to 16 mg/L.NOTES:1. The inclusion of the chelating resin separation step reduces the interference effects of many heavy metals, e.g. 2 mg of iron(III), 5 mg of copper(II) and 5 mg of chromium(III) in the portion applied to the column can be tolerated.Phosphate interferes because it complexes uranium, thus reducing its retention on the resin. Up to 30 mg phosphate can be tolerated in the test portion, and up to 500 mg phosphate can be present when 1 mg of thorium(IV) is added to preferentially complex the phosphate.2. The test portion should contain less than 0.01 mg of vanadium(V). However, up to 0.4 mg of vanadium(V) can be tolerated by reduction to vanadium(IV) with ascorbic acid.3. Iron(III) interferes, and this effect is increased when magnesium(II) is present because it reduces the ability of the complexing solution to mask iron(III). The test portion should contain both less than 15 mg of magnesium(Il) and less than 0.5 mg of iron(III).