Rapid method for the spectrophotometric determination of iridium(IV)

Abstract

Iridium(IV) forms, instantaneously, a red radical cation with perazine dimalonate, at room temperature in a phosphoric acid medium. The radical cation exhibits an absorption maximum at 515 nm and Beer's law is obeyed for up to 24 µg ml^–1 of iridium. Sandell's sensitivity of the reaction is 0.019 µg cm^–2 and the molar absorptivity is 9.93 × 10³ l mol^–1 cm^–1. The tolerance limits to platinum metals, base metals and common anions are reported. The method is applied to the determination of the iridium content in the synthetic mixtures corresponding to the iridium-rhodium fraction separated from platinum metal concentrates.