Application of liquid-liquid microextraction based on deep eutectic solvent for preconcentration and spectrophotometric determination of purpurin

This research used a simple and efficient liquid-phase microextraction method based on deep eutectic solvents for preconcentration and spectrophotometric determination of purpurin (1, 2, and 4-trihydroxyanthraquinone) dye. The choline chloride-acetic acid DES with a molar ratio of 1:2 was synthesized and used with 1-Decanol as the extraction solvent. The influence of effective parameters on the extraction efficiency, including the type and volume of extracting solvents, pH of sample solution, the molar ratio of DES components, and sodium chloride salt concentration were studied, using the response surface method. The highest extraction percentage (>95%) was obtained at pH = 5.5, 550 mg/L of sodium chloride, 350 and 500 µL of DES, and 1-Decanol solvents, respectively. The effect of different ions and dyes on the extraction efficiency was examined and the results indicated that the method has an acceptable selectivity. The present process was linear in the concentration range of 5.0×10-7 to 2.0×10-5 mol/L of purpurine, with a detection limit of 2.7×10-7 mol/L, preconcentration factor of 100, and a relative standard deviation of 3.13%. Finally, to test the applicability of the proposed method, it was investigated for the uptake of purpurin from various water samples, successfully.