Separation and preconcentration of mercury in water samples by ionic liquid supported cloud point extraction and fluorimetric determination

We have developed a cloud point extraction procedure based on room temperature ionic liquid for the preconcentration and determination of mercury in water samples. Mercury ion was quantitatively extracted with tetraethyleneglycol-bis(3- methylimidazolium) diiodide in the form of its complex with 5,10,15,20-tetra-(4-phenoxyphenyl)porphyrin. The complex was back extracted from the room temperature ionic liquid phase into an aqueous media prior to its analysis by spectrofluorimetry. An overall preconcentration factor of 45 was accomplished upon preconcentration of a 20 mL sample. The limit of detection obtained under the optimal conditions is 0.08 μg mL−1, and the relative standard deviation for 10 replicate assays (at 0.5 g mL−1 of Hg) was 2.4%. The method was successfully applied to the determination of mercury in tap, river and mineral water samples.