Combination of three-phase extraction with deep eutectic solvent-based dispersive liquid–liquid microextraction for the extraction of some antibiotics from egg samples prior to HPLC-DAD

In this study, a three-phase extraction method was combined with a deep eutectic solvent–based dispersive liquid–liquid microextraction procedure for the extraction of four antibiotics (doxycycline, enrofloxacin, florfenicol, and chloramphenicol) from egg samples. In this method, a proper amount of egg (yolk and white) was mixed with deionized water. Then n-hexane and acetonitrile were added to the mixture. After adding sodium chloride into the mixture and sonication, acetonitrile was separated and used in the following dispersive liquid–liquid microextraction method. The extracted analytes were concentrated into tetrabutyl ammonium chloride-thymol deep eutectic solvent in the microextraction step. The method optimized by response surface methodology showed acceptable limits of detection and quantification, extraction recoveries, and enrichment factors within the ranges of 0.13–0.49, 0.43–1.63 ng g−1, 64–85%, and 32–43, respectively. The relative standard deviations were less than or equal to 4.6 and 5.1% for intra– and inter–day precisions, respectively. The method was done on different egg samples and enrofloxacin and florfenicol were found in some samples. The analytes were separated and determined by high performance liquid chromatography equipped with diode array detector.