Liquid chromatography-UV determination of heavy metal ions in environmental samples using dispersive liquid-liquid microextraction coupled with magnetic nanoparticles

Abstract

A novel, rapid low-density solvent based dispersive liquid-liquid microextraction combined with magnetic nanoparticles has been developed for extraction and preconcentration of Cr2+, Ni+, Co2+, Hg+ in environmental samples prior to liquid chromatography with UV analysis. In the proposed method, the Schiff base was used as a complexing agent and the environmental samples were treated with acetonitrile/water (60:40, v/v) which was then utilized as disperser solvent in the dispersive liquid-liquid microextraction process along with using 1-octanol as extractant. In magnetic solid phase extraction approach, hydrophobic magnetic nanoparticles were used to retrieve and separate the 1-octanol in the dispersive liquid-liquid microextraction step. In fact the target of magnetic solid phase extraction was the 1-octanol rather than the metal ions directly. Several parameters including the volume of extractant, the pH of the sample, the concentration of complexing agent, the volume of magnetic nanoparticles were optimized. Under the optimized conditions, there coveries obtained for each metal ion ranged from 86 to 106% with relative standard deviations lower than 5.6%. The limit of detection were 0.05 µg L-1 for Cr2+, 0.05 µg L-1 for Ni+, 0.06 µg L-1 for Co2+, 0.05 µg L-1 for Hg+, respectively. The preconcentration factors were 205, 200, 195 and 190 for Cr2+, Ni+, Co2+ and Hg+, respectively. The presented method has been successfully used for the determination of metal ions in real water samples.