Simultaneous spectrophotometric determination of copper(II) and iron(III) as the azide complexes

Abstract

The simultaneous spetrophotometric determination of copper and iron is based on the yellow and red azide complexes formed in 50% (v/v) water/acetone medium. Absorbances are measured at 345 and 435 nm where molar absorptivities for the iron(III) complex are 8.77 × 10 3 and 8.49 × 10 3 l mol −1 cm −1, rspectively, and absorptivities for the copper(II) complexes are 1.47 × 10 3 and 5.69 × 10 3 l mol −1 cm −1, respectively. The systems obey Beer's law and concentrations as low as 2.0 and 1.2 mg l −1 for copper and iron, respectively, can be quantified in a 1.00-cm cell. Determination of iron(III) in 23 mixtures (1.1–5.4 mg l −1) yielded a relative standard deviation of 0.86%; similar data for copper(II) (2.0–8.9 mg l −1) yielded a relative standard deviation of 1.6%.