Facile synthesis of tubular magnetic fluorinated covalent organic frameworks for efficient enrichment of ultratrace polybrominated diphenyl ethers from environmental samples.

Polybrominated diphenyl ethers (PBDEs), known as the most widely used brominated flame retardant, have received great public concern due to its hidden environment and health problems. Development of highly selective and sensitive analytical approaches for enrichment and detection of ultratrace PBDEs are in high demand. Conventional sample pretreatment techniques usually require tedious procedures, long time, and excessive consumption of solvent and sample, thus hindering ultrasensitive detection of PBDEs. To address this issue, we first reported a simple room-temperature approach for synthesis of tubular magnetic fluorinated covalent organic frameworks (MCNT@TAPB-TFTA). The introduction of fluorine atoms played multiple roles in improving the frameworks' hydrophobicity and the adsorption capabilities for PBDEs. Combined with atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS), several crucial parameters of magnetic solid-phase extraction (MSPE) including adsorbent dosage, adsorption time, pH, ion strength, the eluent, elution time and elution frequencies were examined in detail. The optimal method exhibited wide linear ranges (0.01-500 ng/L), low limit of detections (LODs, 0.0045-0.018 ng/L), good correlation coefficients (r ≥ 0.9977), and high enrichment factors (EFs, 1425-1886 folds) for eight PBDEs. Furthermore, this proposed method could be successfully applied to sensitive determination of ultratrace PBDEs in environmental samples, demonstrating the promising potential of the MCNT@TPAB-TFTA as an adsorbent in sample pretreatment.