Determination of 234U and 238U in seawater samples by alpha spectrometry after concentration of U(VI) onto hydrotalcite and co-precipitation with LaF3

Abstract

Summary This paper presents a simple and accurate method for determination of uranium isotopes (234U and 238U) in seawater samples using alpha spectrometry. Uranium is pre-concentrated from seawater samples via adsorption on hydrotalcite at pH 6.5. The absorbent is dissolved into 50 ml of 8M HNO3; then filtered through a Dowex-1 column. U(VI) in the elution solution is reduced to U(IV) using zinc metal in 4M solution of HCl and then co-precipitated with LaF3. The chemical separation efficiency is found to be 97.12±2.68%, eliminating the need of using 232U tracer in other published methods. This method is validated via comparison with results obtained using inductively coupled plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA) for three seawater samples.