Solvent extraction of the thiocyanato mixed-ligand complexes of iron(III) with various hydroxyamidines and spectrophotometric determination of iron(III) in various biochemical and biological samples

Abstract

The reaction in benzene of 11 newly synthesised N-hydroxy-NN′-diarylbenzamidines (HOA) with iron(III) in the presence of thiocyanate has been investigated spectrophotometrically. The study revealed the formation of a 1:2:1 iron(III)-thiocyanate-HOA mixed complex in acidic media (0.2–0.8 M hydrochloric acid). On the basis of this sensitive colour reaction, a simple, rapid, selective and highly reproducible method for the extractive-spectrophotometric determination of microgram amounts of iron(III) in various bio-chemical and biological samples has been developed. The molar absorptivities of the systems are found to be between 1.1 and 1.35 × 10⁴ l mol^–1 cm^–1 in the wavelength range 460–470 nm. The method is free of interference from most of the common metal ions and commonly used sequestering agents. The effects of experimental variables on the procedure are discussed.