CLOUD POINT EXTRACTION FOR THE DETERMINATION OF IRON IN WATER SAMPLES BY SPECTROPHOTOMETRY

Abstract

Total iron content in water samples was determinated by combination of cloud point extraction technique and spectrophotometric method. The method involved a selective hydrophilic complex formation between iron (II) and 1,10-phenanthroline in a buffer pH 5, which can efficiently be extracted in surfactant-rich phase of Triton X-100 and determined spectrophotometrically at λmax 512 nm. Total iron was determinated after the reduction of Fe(III) to Fe(II) by using hydroxylamine as a reducing agent. The main factors that influence the efficiency of cloud point extraction such as the pH of sample solution; the concentration of solutions of 1,10-phenanthroline reagent, hydroxylamine reducing agent, Triton X- 100, salt; the influence of interferences and the impact of equilibration time were studied. The calibration graph was linear in the range of 0.1–1.0 (µg/mL) with r2 = 0.9998. Under optimized conditions, the detection limit was 0.0074 (µg/mL) with the relative standard deviation of 2.80%.