A novel deep eutectic solvent-based ultrasound-assisted dispersive liquid–liquid microextraction coupled with high-performance liquid chromatography for the determination of quinolones in environmental water samples

In this work, a novel deep eutectic solvent composed of thymol and octanol was synthesized and employed as a green extractant for ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) of three quinolones in environmental water followed by HPLC-UV analysis. Parameters affecting UA-DLLME were investigated and optimized. The optimal DES ratio was 2:1, the volume was 150 μL, ultrasonic time was 5 min, and the NaCl concentration was 0.68 mol·L-1. Good linearity was obtained over the concentration range of 1–100 ng·mL−1 with R2 ≥ 0.9986. The limits of detection (LOD) were 0.1–0.3 ng·mL−1 and the limits of quantification (LOQ) were 0.4–1.0 ng·mL−1 with RSD less than 4.8%. The method was fast, sensitive and eco-friendly, which offered a new way to monitor quinolone levels in environmental water.