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A facile and rapid postsynthetic modification strategy for functionalization of covalent organic framework (COF) was developed to synthesize a tailor-made pH-responsive COF called TpPa-1@Au@GSH for highly efficient extraction of N1-methyladenosine (m1A). Glutathione (GSH) was judiciously designed as the functional group for extracting and releasing m1A by pH variations. With the aid of gold nanoparticles (Au NPs) as linkers, GSH was successfully introduced to the robust substrate TpPa-1 in only one step spending only 1 h. Owing to the several-to-one immobilization of GSH on Au NPs and the large surface area of TpPa-1, this functional COF was constructed with abundant m1A binding sites. TpPa-1@Au@GSH showed excellent selectivity for m1A extraction by capturing m1A from a mixture of 14 nucleoside analogues followed by mass spectrometry analysis. It was proved to have ultrafast adsorption ability (only 1 min incubation time), high binding capacity (5 mg g-1, m1A/TpPa-1@Au@GSH), good reusability (at least 5 times), and good storage stability (at least 8 months at room temperature). Great performance was also achieved in extracting m1A from both animal and plant biological samples. The adsorption mechanism was demonstrated to be based on the electrostatic interaction. This work proposed a new approach for m1A extraction, demonstrated the high potential of COFs in biological sample pretreatment, and offered an effective and versatile route for functionalization of COFs.