3.OXIMINOMETHYLSALICYLIC ACID AS AN ANALYTICAL REAGENT. PART II; SPECTROPHOTOMETRIC DETERMINATION OF URANIUM

The use of 3-oximinomethylsalicylic acid as a reagent for the spectrophotometric determination of uranium (VI), with which it develops an orange-red colour in alkaline solution, is described: The wave-length of 400 mμ is found most suitable for absorption measurement. The optimum pH of the solution lies between 6.70 and 9.30 with an excess of the reagent, at least 5 to 6 times the molar proportion of uranium, for the maximum development of colour. The colour is stable at room temperature below 30°. Beer's law holds good in the concentration range of 7.14— 119.0 p.p m. uranium Sensitivity is 0.12 γU/c.c.. The composition (1:1) of the coloured species has been eva­luated by Job's method and the probable constitution suggested. Most cations and anions interfere with the determination of uranium. Hence a preliminary separation of uranium from the interfering ions is essential.