Atomic Absorption Spectrometric and Spectrophotometric Trace Analysis of Uranium in Environmental Samples with N-p-MEthoxyphenyl-2-Furylacrylohydroxamic acid and 4-(2-Pyridylazo) Resorcinol

Methods are presented for the determination of uranium in presence of various anions and cations which are usually associated with it in rocks, waters, minerals, nuclear fission products and biological materials. The methods are based on the solvent extraction of uranium(VI) as its complex with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform, or methyl isobutyl ketone (MIBK) at pH 4.5–5.1. The uranium in the orange-yellow chloroform extract is either directly determined spectrophotometrically or back-extracted into 0.01 M HCl solution and determined as its intensely red coloured complex (ϵ = 3.94 × 104 mol−1 cm−1 at 530 nm) with 4-(2-Pyridylazo) resorcinol (PAR). The metal in the MIBK extract is determined atomic absorption spectrometrically by the aspiration of the extract in nitrous oxide-acetylene flame and measuring the absorbance at 358.5 nm resonance line. Both the methods are highly sensitive and selective, and were applied to the determination of uranium in waters, plants and animal tissues.