Determination of liquid crystal monomers in environmental water by ultrasound-assisted pH-responsive deep eutectic solvent based homogeneous liquid-liquid microextraction

As a growing concern in aqueous systems, liquid crystal monomers (LCMs), have been widely detected in the environment and organisms, posing a potential threat to ecosystems and human health. Conventional liquid-liquid extraction methods based on organic solvents are operationally complex, time-consuming, and environmentally unfriendly. Switchable deep eutectic solvents (SDESs) have emerged as environmentally friendly solvents have shown promise for extracting pollutants from water for detection. Herein, an ultrasound-assisted homogeneous liquid-liquid microextraction (UA-HLLME) method coupled with pH-responsive switchable deep eutectic solvents (SDESs) for extracting LCMs from environmental water samples was established. We validated the established method by gas chromatography-mass spectrometry (GC-MS), and excellent linearity (R²≥0.9984) were obtained across a concentration range of 2.5-500 ng·mL⁻¹. The limits of detection (LODs) ranged from 0.09 to 0.66 ng·mL⁻¹, and the limits of quantification (LOQs) were 0.30-2.21 ng·mL⁻¹. Satisfactory recoveries (88.32%-127.79% for artificial lakes and 94.73%-134.73% for rivers) and enrichment factors (12-19) were obtained in environmental water samples. The method enhanced the preconcentration efficiency and have advantages of operational simplicity, high efficiency and environmental friendliness. This work lays a foundational basis for the future development of innovative SDES-UA-HLLME based technologies in the detection of LCMs in environmental matrices.