Spectrophotometric determination of iron species using ionic liquid ultrasound assisted dispersive liquid–liquid microextraction

A simple and efficient method for speciation and determination of iron in different water samples was developed. The method is based on ionic liquid ultrasound assisted dispersive liquid–liquid microextraction (IL-USADLLME) followed by spectrophotometric determination. Fe(II) is complexed with 2,4,6-tri(2’-pyridyl)-l,3,5-triazine (TPTZ), neutralized through ion pair formation with sodium dodecyl sulfate (SDS) and extracted into 1-hexyl-3methylimidazolium hexafluorophosphate [C6MIM][PF6 ]. Total iron amount was determined after reduction of Fe(III) to Fe(II) with hydroxylamine hydrochloride. The concentration of Fe(III) was determined from the difference of concentration of total iron and Fe(II). The important parameters such as the type and volume of the extraction solvent, pH, ligand concentration, and ionic-strength were optimized. Under the optimum conditions, the calibration graph was linear over the range of 5.0–140.0 μg L−1 with the detection limit of 0.2 μg L−1 . The relative standard deviation for five replicates measurement of 100 μg L−1 of Fe(II) was 1.5%. The proposed method was successfully applied to the determination of iron species in water samples.