Green vortex-assisted emulsification microextraction using a ternary deep eutectic solvent for extraction of tetracyclines in infant formulas

A novel green alternative vortex-assisted emulsification liquid–liquid microextraction based on a new hydrophobic deep eutectic solvent (DES) was developed to extract tetracyclines in infant formulas. Five new ternary DESs were synthesized and tested in this regard. Among them [thymol]:[ethylene glycol]:[benzyl alcohol] (2:2:1) DES demonstrated the highest extraction efficiency. The analyzes were performed by HPLC. The DES was characterized by attenuated total reflectance-FTIR, nuclear magnetic resonance spectroscopy, and octanol–water partition coefficient. The effect of type, mole ratio, and volume of DES, dispersing agent, pH, and ionic strength was studied. The limits of quantification and linear range were 3–9.32 and 3–500 μg kg−1, respectively. The method was applied to detect tetracyclines in infant formulas, and the recoveries were obtained as 68.9–102.0 % with relative standard deviations < 9 %. The procedure greenness was assessed using the Analytical Eco-Scale. This paper represents the first application of a novel ternary DES to analyze tetracyclines in infant formulas.