Surfactant-Assisted Dispersive Liquid-Liquid Microextraction for Sensitive Spectrophotometric Determination of Iron in Food and Water Samples and Comparison with Atomic Absorption Spectrometry

A technique of selective and sensitive surfactant-assisted dispersive liquid-liquid microextraction combined with spectrophotometry was developed for determination of iron in water and food samples. This method involves the formation of a red-colored iron-thiocyanate complex in the presence of cetyltrimethylammonium bromide (CTAB) as cationic surfactant. The use of CTAB assisted in color formation and effective extraction of the complex into the organic solvent through micelle formation prior to spectrophotometric and flame atomic absorption spectrometry measurement. Optimum absorbance and extraction of the iron complex was obtained with concentrations of ammonium thiocyanate, N-phenylbenzimidoyl thiourea, CTAB and sodium chloride of 0.30 M, 3.0 x 10(-3) M, 0.40 x 10(-3) M and 1.0 %, respectively. The calibration curve was linear over a range of 20-350 ng mL(-1) iron with correlation of estimation (R (2)) of 0.997. The proposed method was successfully applied to the determination of iron in food (cereal, fruit and vegetable) and water samples.