EXTRACTION AND SPECTROPHOTOMETRIC DETERMINATION OF IRON(III) WITH N-1-HYDROXY-N-1,N-2-DIPHENYLBENZAMIDINE AND THIOCYANATE

N-1-Hydroxy-N-1,N-2-diphenylbenzamidine (HDPBA) was found to react wit h iron(III) in the presence of thiocyanate to form an orange-red mixed ligand complex having a composition of 1:2:2 (Fe:HDPBA:SCN-). The com plex was found to be quantitatively extractable into toluene from 0.1- 0.6 M hydrochloric acid solutions. The spectrum of the complex exhibit ed a maximum absorption at 465 nm with a molar absorptivity of 1.0 x 1 0(4) M(-1) cm(-1). The photometric sensitivity of the colour reaction was found to be 0.0056 mu g cm(-2) of iron and the coloured system obe yed Beer's law in the concentration range 0.2-6.4 mu g ml(-1) of iron. The effects of foreign ions and of experimental variables on the extr action and determination of iron(III) have been studied. The method ha s been found to be precise, reliable, sensitive, and highly selective. The method has been applied successfully to the determination of iron in ores, steels, blood, vitaminized syrup, and water.