Application of an In-situ Solvent Formation Microextraction Technique Using the Functionalized Ionic Liquids (FILs) as a Green Extractant for Cadmium Determination at Trace Levels in Real and Saline Samples

An in-situ solvent formation microextraction technique, as an attractive mode of homogeneous liquid-liquid microextraction, was developed successfully for the sensitive extraction of cadmium ion. In this technique, green extracting solvents such as ionic liquids are used. Due to using ionic liquids, this technique is much safer than other extraction methods using toxic common organic solvents. Functionalized ionic liquid of 3-(2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)ethyl)-1-methylimidazolium bromide was used as an extractant and organic phase which has a double role including complexing agent and extractant, so the extraction of cadmium ion does not need any complexing agent. To optimize the extraction conditions, several analytical parameters affected the microextraction efficiency including sample pH, functionalized ionic liquid dosage, counter-ion amount and centrifugation conditions were studied. To show abilities of the method, the figures of merits including limit of detection and quantification, relative standard deviation, linear dynamic range and enrichment factor were calculated which were found to be 0.23 μg l-1, 0.76 μg l-1, 1.8%, 10-1500 μg l-1 and 75, respectively. It was found that the method could be successfully applied for the determination of Cd(II) ion in several real, and saline samples. Due to the use of environmental solvents, such as ionic liquids, and their small dosage, it can be said that the method has a low toxicity and classified as a green extraction/preconcentration technique. The proposed method opens a new window in the analytical applications due to its low cost, ease in experimental setup and use of non-toxic solvents as an extractant.