Determination of Trace Levels of Cu2+ Using Ultrasonicated Dispersive Liquid Phase Microextraction Based on Deep Eutectic Solvents Followed by Flame Atomic Absorption Spectrometry

In this paper, liquid phase microextraction technique based on deep eutectic solvent was used for preconcentration of trace levels of Cu2+ followed by its determination by flame atomic absorption spectrometry (FAAS). 8-Hydroxy quinolone (oxine) was used as a complexing agent and the mixture of choline chloride-phenol with a mole ratio of 1:3 was used as an extraction solvent. By using ultrasonicated dispersive liquid phase microextraction technique, the extraction solvent was dispersed in the sample solution and extracted the hydrophobic complex in a short time. Different parameters affecting the relative recovery including pH of sample solution, concentration of complexing agent, mole ratio of extraction solvent component, volume of extraction solvent, extraction time and volume of aprotic solvent (tetrahydrofuran) were completely investigated and optimized. Under the optimum conditions, the calibration curve was linear in the range of 20-300 µg L-1 Cu2+ with a limit of detection of 4.5 µg L-1 Cu2+ (n=8). Also, the relative standard deviation based on seven replicate analysis of solution containing 50 µg L-1 Cu2+ was 3.1%.  Finally, the proposed efficient, rapid and green liquid phase microextraction was successfully used for determination of trace levels of Cu2+ in different water samples.