Determination of uranium in phosphate rocks, gypsum and crude phosphoric acid samples by potentiometry

This paper describes a potentiometric method for the determination of ppm level uranium in phosphate rock samples. Samples as received were containing large quantities of humus material which should be decomposed by fuming with nitric acid-sulphuric acid mixture. The resultant slurry was directly analysed for uranium by modified Davis and Grey method with potentiometric end point determination. The values compared well with those obtained by laser fluorimetric method. A RSD of 1 % was obtained for a set of ten replicate measurements. (author)