A highly selective photometric method for uranium(VI) using a pyrimidyl azo dye in the presence of EDTA

The sodium salt of 2,4,6-tris(1-hydroxy-4-sulphonaphthyl-2-azo)pyrimidine gives a 1:1 violet coloured complex with uranyl(II) at pH 5.5–6.5 in the presence of EDTA absorbing maximum at 560 nm, where no other metal, including lanthanides, forms a complex. The Sandell's sensitivity of colour reaction is 6.14 ngU(VI)/cm². The developed method has been applied to the determination of uranium(VI) in synthetic samples corresponding to mineral monazite and some uranium alloys.