In-situ synthesis of fluorinated magnetic covalent organic frameworks for fluorinated magnetic solid-phase extraction of ultratrace perfluorinated compounds from milk.

•Fluorinated magnetic COFs were synthesized via in-situ growth strategy.•The magnetic COFs exhibited high adsorption performance towards six PFCs.•The FM-SPE-HPLC-MS/MS method was simple, fast, highly efficient and selective.•The developed method can be applied for the detection of ultratrace PFCs in milk.