Colorimetric reaction behavior of 1-(2-quinolylazo)-2,4,5-trihydroxybenzene (QATB) has been established with uranium(VI) under various physicochemical conditions. An addition of dilute solution of uranyl ions to the dimethylformamide (DMF) solution of QATB, resulted to form a brown colored complex which was soluble if 30% DMF concentration was maintained. The brown colored complex absorbing maximum at 560 nm in the pH range 6.5-7.5. Beer’s law was valid over concentration range 0.0-14.0 ppm, with molar absorptivity and Sandell’s sensitivity of 1.9 x 104 L.mol-1. cm-1 and 0.0125 µg cm2, respectively. The molar composition of the complex was 1:2 (M:L) as determined by Job’s method of continuous variation. The tolerance limits for interfering ions are discussed. All variables were studied in order to optimize the reaction conditions. The efficiency of the proposed method is shown by the successful determination of traces of uranium in some ores.
Spectrophotometry, QATB, Uranium, Ores