Spectrophotometric determination of Europium by using Arsenazo III as a chromogenic reagent

Simple and fast spectrophotometric procedure has been standardized for the determination of Europium(III) using chromogenic reagent Arzanazo III. The given solution containing, appropriate amount of Eu(III) was complexed with arsenazo(III) in a 10mL volumetric flask by adding appropriate amount of aqueous solutions (0.01M HCl, 0.01M HClO₄ or 0.01M H₂SO₄) having a pH of approximately 2. Jobs method of continues variation was carried out in order to understand the complex formation of Eu(III) with arsenazo(III). From the interference studies it was observed that oxalic acid, Fe³⁺, U(VI), Th(IV) etc are showing interferences. Described procedure can be used for the determination of europium in real samples, provided it is free from certain interfering ions. (author)