Simultaneous derivative spectrophotometric determination of thorium and uranium in a micellar medium

Derivative photometric methods for trace analysis of Th(IV) and UO2(II), and their simultaneous determination in mixtures using 5,8-dihydroxy-1,4-naphthoquinone in a micellar medium are reported. Molar absorptivity and Sandell's sensitivity of 1:2 Th(IV) and 1:1 UO2(II) complexes at 614.5 nm and 637.0 nm are, 1.19 x 104 1/mol/cm and 1.12 x 104 1/mol/cm and 1.95 x 10-2 μg/cm2 and 2.13 x 10-2 μg/cm2, respectively. Calibration graph is linear over the range 9.28 x 10-2 - 18.56 μg/ml of Th(IV) and 9.52 x 10-2 - 19.04 μg/ml of UO2(II). Though presence of Th(IV) and UO2(II) causes interference in each others determination, 9.28 x 10-1 -9.28 μg/ml Th(IV) and 9.52 x 10-1 - 9.52 μg/ml UO2(II) when present together, can be simultaneously determined using derivative spectra. (Author)