Ionic liquid-based dispersive liquid–liquid microextraction combined with inductively coupled plasma-optical emission spectrometry for preconcentration of some heavy metals in complex matrices

A simple, rapid, and efficient dispersive liquid-liquid microextraction technique based on ionic liquid (IL-DLLME), followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for the simultaneous preconcentration and determination of cobalt, copper, and zinc in herbal and water samples. In the proposed approach, N,N΄-bis(Salicyliden)-2,2-dimethyle-1,3-propanediamine and acetone were used as the chelating agent and disperser solvent, respectively.1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF6]) was selected as extraction solvent, instead of usage of toxic water-immiscible chlorinated solvents. Some factors influencing the extraction efficiency of metal ions, including type of extraction and disperser solvents, volume of extraction and disperser solvents, sample pH, the amount of chelating agent, extraction time, centrifugation rate, and salt amount were studied and optimized. Under optimized conditions, preconcentration  factor of 83, limits of detection (LODs) of 0.88-1.3μg L-1,and the relative standard deviations (RSDs) of 1.95-2.51% (n=8) were obtained. Real samples including mineral water, well water, cabbage, and pomegranate juice were analyzed by proposed method and yielded recoveries ranged from 90.2% to 100.2%. High metal ions recoveries imply on effectiveness of IL-DLLME for efficient preconcentration of metal ions in mentioned real samples.