Abstract
A method is described for the determination of uranium by using a dc argon plasma emission spectrometer. Problems and interferences found in the method previously reported are overcome by using an improved sample pretreatment. A new synergistic system, 2% oxalic acid adjusted to pH 4.5 with triethanolamine, is used to quantitatively back-extract uranium from trioctylphosphine oxide in cyclohexane. This improved method yields excellent results for >1 ppm uranium in nitric and hydrochloric acid solutions of phosphate rocks, phosphoric acids, phosphate fertilizers, phosphogypsums, organic phosphates, and waste solutions. Recovery data are given for synthetic and certified standards.
