Ultrasound-assisted surfactant/ionic liquid aqueous two-phase system extraction prior to high performance liquid chromatography for the determination of tetracyclines in milk and honey samples

In this work, an ultrasonic-assisted surfactant/ionic liquid aqueous two-phase system (ATPS) extraction method was developed to extract six tetracycline antibiotics from food samples before their chromatographic determination using high performance liquid chromatography. The ATPS was formed with 1-allyl-3-methyl-imidazolium bromide, Triton X-100, and dipotassium hydrogen phosphate. The parameters including type and amount of surfactant, ionic liquid and salt, pH of sample solution, and sonication time were optimized. Under the optimized conditions, linear calibration curves of the six tetracyclines were obtained in the range of 10--500 $\mu $g L$^{-1}$ with $>$ r$^{2} =$ 0.990 (n $=$ 9). The proposed green analytical extraction method was applied to the analysis of tetracycline antibiotics in milk and honey samples with recovery of 50%--110% and 68%--117%, respectively.