Fluorinated Microporous Organic Network-Based Cooling-Assisted SPME for Ultra-Trace Determination of Fluorinated Liquid Crystal Monomers

Abstract Fluorinated liquid crystal monomers (FLCMs), widely used in electronic displays, have emerged as persistent and bioaccumulative contaminants, yet their ultra-trace determination in complex matrices remains challenging. Herein, a cooling-assisted solid-phase microextraction (CA-SPME) method based on a fluorinated microporous organic network (F-MON) coating, coupled with GC−MS/MS, is developed for ultra-trace determination of FLCMs in environmental water and soil. The F-MON coating, featuring abundant fluorinated active sites and a hierarchical porous structure, provides strong affinity toward FLCMs via synergistic fluorine−fluorine, hydrophobic, and π−π interactions. A self-designed cooling-assisted device establishes a temperature gradient that suppresses analyte desorption and enhances partitioning into the extraction phase. The method exhibits rapid adsorption kinetics and multilayer adsorption behavior. Under optimized conditions, ultralow limits of quantification (0.02−0.26 pg mL−1) and high enrichment factors (6394−15782) are achieved, with excellent linearity (r ≥ 0.9995), good reproducibility (RSDs ≤ 11.5%), and negligible matrix effects (−22.1% to 20.7%). Compared with existing approaches, this method offers reduced sample and solvent consumption, simplified operation, and superior sensitivity. This work provides a robust analytical platform for trace FLCMs and highlights the synergistic potential of fluorinated porous fiber materials and cooling-assisted extraction strategies in advanced sample pretreatment.