In situ deep eutectic solvent based liquid-phase microextraction coupled with HPLC for the determination of quinolone antibiotics in wastewater samples

An in situ DES-LLME/HPLC-DAD method was developed for detecting trace quinolones in wastewater. • Quinolones were used as hydrogen bond acceptors for in situ DES formation. • The method showed good linearity with low LODs of 0.094–0.905 μg/L and satisfactory recoveries. • The method was applied to real samples, confirming its potential for antibiotic monitoring. Background Quinolone antibiotics are widely used in human and veterinary medicine due to their broad-spectrum antibacterial activity and cost-effectiveness. However, their environmental persistence and frequent occurrence in aquatic systems have raised concerns regarding potential ecological risks. Accurate risk assessment requires sensitive analytical methods capable of detecting trace levels of quinolones in complex environmental matrices. Traditional preconcentration techniques like solid-phase extraction and liquid-liquid extraction face several limitations including high-cost sorbents, sorbent degradation, memory effects, labor-intensive procedures, large solvent consumption, and the use of toxic organic solvents. Results To address these challenges, we developed a sensitive method for the determination of trace quinolones in water samples by integrating in-situ deep eutectic solvent-based liquid-liquid microextraction with high performance liquid chromatography coupled with a diode array detector. A key innovation of this approach lies in the utilization of the target quinolones as hydrogen bond acceptors during in situ DES formation, enabling direct extraction from aqueous media. Through theoretical screening using the conductor-like screening model for real solvents (COSMO-RS) and subsequent experimental verification, butyl 4-hydroxybenzoate was identified as the optimal hydrogen bond donor. Under the optimized extraction conditions, enrichment factors ranged from 33.43 to 66.50, with corresponding extraction recoveries of 33.43–66.50%. The method demonstrated satisfactory sensitivity, with limits of detection ranging from 0.094 to 0.905 μg/L, good linearity with determination coefficients exceeding 0.99, high accuracy with recoveries of 82.25%–122.08%, and acceptable precision with relative standard deviations below 13.76%. Application to real wastewater samples successfully detected enrofloxacin (20–39 μg/L) and moxifloxacin (20 μg/L), confirming the practical feasibility of the proposed method. Significance This in situ deep eutectic solvent-based liquid-liquid microextraction method offers a rapid, sensitive and efficient approach for monitoring quinolone antibiotics in aquatic environments. Its innovative design not only enables effective determination of quinolones but also holds considerable promise for developing novel in-situ DES enrichment strategies aimed at detecting other emerging environmental pollutants in complex matrices, thereby offering substantial potential for environmental monitoring and risk assessment. Download: Download high-res image (133KB) Download: Download full-size image