Analytical Applications of 8-Hydroxyquinoline Derivatives of Gallium and Thallium.

摘要

Precipitation of gallium and thallium (III) from aqueous solutions with 8-hydroxyquinoline is quantitative at pH values above 3.1 and 3.8, respectively, and provides bases for procedures for the gravimetric determination of these cations. Precipitation of thallium (I) with this reagent is incomplete even under optimum conditions. The 8-hydroxyquinoline derivatives of all three ions dissolve readily in chloroform to yellow solutions which undergo photochemical decomposition, at a rate that increases in the order gallium-thallium(III)-thallium (I). Spectrophotometric studies on chloroform solutions over the range 300 to 1000 mmu indicate each compound to be characterized by broad absorption bands in the ranges 320 to 328, 335 to 338, and 392.5 to 402 mmu. Absorption bands in the last range obey Beer's law and are free from interference by 8-hydroxyquinoline. Both gallium and thallium (III) may be determined spectrophotometrically as 8-hydroxy- quinoline derivatives, but the photochemical sensitivities of thallium(I) solutions preclude use for quantitative work. jg p.1.