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

Derivative photometric methods for trace analysis of Th(IV) and UO(2)(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 UO(2)(II) complexes at their lambda(max), 614.5 nm and 637.0 nm are, 1.19 x 10(4) 1/mol/cm and 1.12 x 10(4) 1/mol/cm and 1.95 x 10(-2) mug/cm(2) and 2.13 x 10(-2) mug/cm(2) mug/cm(2), respectively. Calibration graph is linear over the range 9.28 x 10(-2)-18.56 mug/ml of Th(IV) and 9.52 x 10(-2)-19.04 mug/ml of UO(2)(II). Though presence of Th(IV) and UO(2)(II) causes interference in each others determination, 9.28 x 10(-1)-9.28 mug/ml Th(IV) and 9.52 x 10(-1)-9.52 mug/ml UO(2)(II) when present together, can be simultaneously determined using derivative spectra.