title: Spectrophotometric determination of lanthanum, thorium and iron(III) with chromotropic acid azo dyes of the pyridine series.
abstract: Highly sensitive methods for the determination of lan thanum, thorium and iron(III) have been developed with the sodium salts of 2-(pyridyl-2-azo)chromotropic acid, 2-(pyridyl-3-azo)chromotropic acid and 2-(2-carboxypyridyl-3-azo)chromotropic acid. Optimum concentration ranges are of the order 1-20 ppm. The effect of diverse ions (cations and anions) including those of rare-earths are reported. The nature of the complexes has been investigated and values for the instability constants are given.
authors.affiliation: Department of Inorganic and Analytical Chemistry, Jadavpur University, Calcutta-32, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Majumdar
authors.forename: A B
authors.initials: AB
authors.lastname: Chatterjee