Complexation reactions of uranyl with arsenazo III

The effect of pH and anions on the complexation of uranyl with arsenazo III was investigated using spectrophotometric techniques together with computer simulations. It was found that the 1 : 1 arsenazo III–uranyl complex has four protonation states which respectively dominate at pH 2.2, 5.0, 7.8 and > 10.0. Anions have a significant effect on complexation by interacting with both the free uranyl and the arsenazo III–uranyl complex. Formation constants and molar absorptivities of the various complexes were calculated.