pH-induced deep eutectic solvents based homogeneous liquid-liquid microextraction for the extraction of two antibiotics from environmental water

A fast and efficient kind of homogeneous liquid-liquid microextraction based on the pH-induced transition of deep eutectic solvents (DES-HLLME) was developed for the analysis of two common antibiotics in environmental water, levofloxacin (LOF) and ciprofloxacin (COF). The phase transition behavior of the DESs consisting of thymol and medium-chain fatty acids could be induced by adjusting the solution pH. The consistency and completeness of the DES through phase transition were studied. Then DESs were applied as extractant in HLLME, the important factors, such as types of DES, the volume of DES, the concentration of KOH, the addition of HCl and salt were investigated. Under optimal conditions, the proposed method showed good linear range from 0.5 to 100 mu g mL(-1) (R-2 >= 0.9998), satisfied repeatability (LOF: RSD <= 4.21%; COF: RSD <= 3.57%), high extraction recoveries (LOF: 110.83%; COF: 94.52%).