Extractive—spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone

Abstract

The optimum conditions for the extractive—spectrophotometric determination of trace iron(II) with di-2-pyridylmethanone 2-(5-nitro)pyridylhydrazone have been established. Iron(II) reacts with this reagent at pH 2.0–7.5 to form an uncharged 1:2 (metal-to-ligand) complex, which can be extracted with toluene. Beer's law is obeyed over the range up to 0.84 μg/ml of iron(II) at 505 nm. The molar absorptivity of the extracted species is 5.83 × 10 4 1·mole −1·cm −1. The proposed method is extremely sensitive and reproducible, and has been satisfactorily applied to the determination of total iron in freshwater samples by adding ascorbic acid to reduce iron(III).