title: The reaction of uranyl ions with 4-(2-pyridylazo)resorcinol.
abstract: The uranyl ion and 4-(2-pyridylazo)resorcinol (PAR) form only 1:1 chelates in solutions of pH < 8.5, UO(2),(PAR)H(+) being formed at pH > 3 and UO(2),(PAR) at pH > 5.5. Equilibrium constants and spectrophotometric data for both chelates are given. Solid, non-stoichiometric crystalline species in which the mole ratio of PAR to uranium is more than 1:1 are precipitated up to pH 6. The medium of 0.1-0.2M triethanolamine at pH 8 recommended by other workers proved satisfactory for the sensitive spectrophotometric determination of uranium, as did pH 3.6 in the presence of < 0.1M formate or 20-30% v/v dimethylformamide.
authors.affiliation: Department of Analytical Chemistry of the J.E. Purkyne-University, Brno, Czechoslovakia.
authors.forename: L
authors.initials: L
authors.lastname: Sommer
authors.forename: V M
authors.initials: VM
authors.lastname: Ivanov
authors.forename: H
authors.initials: H
authors.lastname: Novotná