Porous covalent organic frameworks-improved solid phase microextraction ambient mass spectrometry for ultrasensitive analysis of tetrabromobisphenol-A analogs

Owing to frequent environmental monitoring of tetrabromobisphenol-A (TBBPA) analogs and their potential ecotoxicological effects on organisms, analysis of trace levels of TBBPA analogs with more non-polar and less water-soluble characteristics is of great significance for studying their environmental behaviors and toxic effects. Herein, a fast and sensitive technique is developed for directly detecting aqueous TBBPA analogs, including TBBPA mono(allyl ether) (TBBPA-MAE), TBBPA mono(2,3-dibromopropyl ether) (TBBPA-MDBPE), TBBPA mono(2-hydroxyethyl ether) (TBBPA-MHEE) and TBBPA mono(glycidyl ether) (TBBPA-MGE), by combining solid phase microextraction (SPME) based on porous covalent organic frameworks (Porous-COFs) with constant flow desorption ionization-mass spectrometry (CFDI-MS). As chromatographic separation is replaced by constant flow desorption, each sample can be analyzed within 7 min. The hierarchical porous structures (microporous, mesoporous and macroporous) of COFs lead to the enhanced mass transfer and the easier accessibility of active sites to TBBPA analogs, so that the extraction efficiency is 2.3–3.6 times higher than pure microporous COFs, and far superior to commercial coatings. The detection limit and quantification limit of this method are 0.1–1 and 0.4–3.2 ng/L, respectively. Ultra-trace levels of TBBPA analogs from 5.0 ng/L to 66 ng/L have been successfully detected in river and sea water samples, showing great potential for subsequent studies of their environmental behaviors and toxicological effects