Synergistic fluorine-affinity and temperature-gradient-assisted solid-phase microextraction for ultrasensitive...

Liquid crystal monomers (LCMs) have recently emerged as contaminants of increasing environmental concern owing to their widespread use in liquid crystal display devices, environmental persistence, bioaccumulation potential, and adverse toxicological effects. Indoor dust represents a major exposure pathway for human intake of LCMs; however, their ultra-trace concentrations and the complexity of dust matrices pose substantial challenges for accurate determination. Herein, a fluorinated porous organic polymer (F-POP)-coated solid-phase microextraction (SPME) fiber was developed for the selective enrichment of fluorinated liquid crystal monomers (FLCMs). F-POP provides multiple complementary adsorption mechanisms, including fluorous interaction, π-π stacking, hydrophobic interactions, and pore-filling effects, while a newly designed cooling-assisted headspace SPME (CA-HS-SPME) device equipped with dual-cooling structures provides an enhanced temperature gradient to promote analyte partitioning and mass transfer. The proposed CA-HS-SPME strategy increased extraction efficiencies by 40-108% compared with conventional HS-SPME. Coupled with gas chromatography-mass spectrometry (GC-MS), the developed method achieved enrichment factors of 1360-5672, excellent linearity over 10-1000 pg mL^-1 (r ≥ 0.9997), limits of quantification of 1.05-2.74 pg mL^-1, and satisfactory recoveries of 89.3-118.0%. The method was successfully applied to the determination of four FLCMs in indoor dust samples, demonstrating its capability for sensitive and reliable quantification of ultra-trace fluorinated contaminants in complex environmental matrices. The proposed analytical method provides an effective strategy for environmental monitoring and human exposure assessment of FLCMs and may be extended to the determination of other fluorinated emerging contaminants.