Spectrophotometric determination of uranium(vi) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

Abstract

A new reagent, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (bromo-PADAP), is described for the spectrophotometric determination of uranium(VI). This reagent is highly sensitive towards uranium, the uranyl complex having a molar absorptivity of 74,000 at 578 nm and pH 7.6. In the presence of a mixed masking solution only a few ions interfere seriously, and the method can be made specific for uranium by a preliminary extraction of uranium into tri-n-octylphosphine oxide, and direct development of the bromo-PADAP colour in the organic phase. Details are given for the determination of uranium in waters, ores, phosphoric acid and phosphate rocks, thorium oxide, and zirconium oxide. © 1971.