DETERMINATION OF THORIUM USING PHENYLFLUORONE AND QUERCETIN IN THE PRESENCE OF SURFACTANTS AND PROTECTIVE COLLOIDS

Two sensitive spectrophotometric methods have been proposed for the de termination of thorium with phenylfluorone (PF) and quercetin (Quer) i n the presence of cetylpyridinium bromide (CPB) and polyvinylpyrrolido ne (PVP), respectively. The optimum conditions for complexation reacti ons have been thoroughly investigated Tile 1:3:4 (Th-PF-CPB) ternary c omplex and the 1:3 (Th-Quer) binary complex in the presence of PVP, ar e formed in the pH range 8.0-8.6 and 9.8-10.6, with molar absorptiviti es of 1.55x10(5) and 6.25x10(4) l.mol(-1).cm(-1), at 568 and 445 nm, r espectively, The methods ate rectilinear for 0.10-1.66 and 0.21-4.3 mg Th.l(-1) and their detection limits (signal-to-noise ratio = 3) are 0 .082 and 0.139 mg.l(-1), respectively. Results of analysis of thorium in monazite samples using these methods were in good agreement with th ose obtained by x-ray fluorescence spectrometry.