Eco-friendly ultrasonic assisted liquid–liquid microextraction method based on hydrophobic deep eutectic solvent for the determination of sulfonamides in fruit juices

A sensitive, fast, eco-friendly ultrasound assisted liquid–liquid microextraction (LLME) in combination with hydrophobic deep eutectic solvent (DES) method was developed to preconcentrate and extract sulfonamides in fruit juices, prior to high-performance liquid chromatographic (HPLC) analysis. The DES was synthesized with trioctylmethylammonium chloride (TAC) and 2-octanol at the molar ratio of 1:2. Some parameters which affected the extraction efficiency were investigated and optimized, including the volume of DES, extraction method, extraction time, pH. Under the optimum conditions, good linearity ( r  = 0.9999) in the range of 0.1–50 µg mL −1 was obtained. The limit of detection (LOD) was 0.02–0.05 µg mL −1 . And the accuracy of the developed method was confirmed by analysis of spike method, the recoveries were in the range of 88.09–97.84% at the spike levels of 2–20 µg mL −1 in fruit juices.