Ionic liquid based dispersive liquid-liquid microextraction procedure for the spectrophotometric determination of copper using 3-dimethylamino rhodanine as a chelating agent in natural waters

In this work, a novel ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) method has been developed for spectrophotometric copper determination in natural waters. The method is based on the extraction of Cu(II) in the form of a complex with 3-dimethylamino rhodanine and determination using spectrophotometry. In the IL-DLLME, 3-dimethylamino rhodanine and Triton X-100 were used as chelating agent and anti-sticking agent. 1-Heptyl-3-methylimidazolium hexafluorophosphate and ethanol were selected as extractive and disperser solvents, respectively. The following experimental conditions were optimized: pH 3.0, 5 × 10−6 mol L−1 complexing reagent, centrifuge for 1 min at 5000 rpm. The method is linear in the range from 2.2 to 12.2 μg/mL with a correlation coefficient (R2) of 0.9968 and a limit of detection (LOD) of 0.81 μg/mL. The proposed method was successfully applied to the determination of Cu(II) in water samples.