Spectrophotometric determination of iron(II) with 2-(3′-sulfobenzoyl)pyridine benzoylhydrazone

Abstract

A new, water-soluble hydrazone ligand, 2-(3-sulfobenzoyl)pyridine benzoylhydrazone (SBPBH), was prepared and used in the spectrophotometric determination of trace iron( II). The proton dissociation constants of the ligand determined spectrophotometrically were p K a1 = 3.6 6and p K a2 = 10.6 3at 25 ° C and μ = 0.2 (NaCl). Iron( II) reacts with SBPBH to form a 1:2 metal to ligand ratio complex, which has an absorption maximum at 646 nm. The optimum pH range for the formation of the complex is 7–11. Beer's law is obeyed over the range 0–4 ppm of iron( II). The proposed method was applied to the determination of the total iron in natural water samples.