Spectrophotometric and analogue derivative spectrophotometric determination of micro-amounts of iron with 2,2′-dipyridyl-2-benzothiazolylhydrazone

Abstract

The synthesis of 2,2′-dipyridyl-2-benzothiazolylhydrazone (DPBH), characteristics, reactions with various metal ions and its application in the selective determination of iron are presented. DPBH reacts with iron(II) to form a stable 1:3 metal to ligand complex having absorption maxima at 427 and 615 nm in 0.4% Triton X-100 solution. A solution of the complex gives a constant absorbance in the pH range 4.5–8.4 at 427 nm and 3.0–9.6 at 615 nm. The molar absorptivity, sensitivity for an absorbance of 0.001 and relative standard deviation for 10.3 µg of iron (10 replicates) are 3.41 × 10⁴ and 1.23 × 10⁴ l mol^–1 cm^–1, 1.64 and 4.54 ng cm^–2, and 0.7 and 0.5% at 427 and 615 nm, respectively. Application of the proposed method to the determination of iron in water samples and further sensitisation of the method by employing analogue derivative spectrophotometry are also described.