Thallimetric oxidations Part VII: Titrimetric and spectrophotometric methods for the determination of hypophosphite and ternary mixtures of hypophosphite, phosphite, and oxalate

Abstract

Titrimetric and spectrophotometric methods are developed for the estimation of hypophosphite (PO23−) at mmol and micromol ranges, respectively. In these methods thallium(III) is used as an oxidant and the reduced thallium(I) is determined either oxidimetrically by potassium bromate in the titrimetric method or by measurement of the optical density of thallium(III) at 260 nm in the presence of 0.1 M NaCl and 1 M HClO4 in the spectrophotometric method. Convenient methods are described for the determination of ternary mixtures of hypophosphite (PO23−), phosphite (PO33−), and oxalate (C2O42−). A method is also described for the estimation of thallium(III) using hypophosphite as reductant, and the method is applied to the determination of mixtures of thallium(I) and thallium(III).