Fully automatic flow injection system for the determination of uranium at trace levels in ore leachates

Abstract

An automatic flow injection system is described for the determination of uranium in ore leachates. Following injection from an autosampler, the leachate is extracted with a solution of tributyl phosphate in heptane, which removes uranium, and the organic phase is separated. The extract is reacted with an ethanolic solution of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (BrPADAP) and benzyldimethyltetradecylammonium chloride (zephiramine) and the resulting ternary complex with U(VI) is measured spectrophotometrically at 579 nm. The lower limit of determination is 0.1 p.p.m. of uranium and up to 50 samples per hour can be analysed. In terms of speed and sensitivity this improves significantly on published procedures using segmented flow systems. The technique is ideal for process control and can be applied to the analysis of ores following mineralisation.