Exploring the chromatographic performance of octadecanethiol modified spherical covalent organic frameworks stationary phase.

In recent years, covalent organic frameworks (COFs) have attracted considerable attentions with the advantages of high specific surface area, ordered pores, and excellent stability. However, the nanoscale size and irregular morphology of COFs have led to high back pressure, which hindered their application and development in the field of separation. Herein, we synthesized uniform spherical COFs via Schiff-base condensation by regulating the amount of acetic acid. Then, octadecanethiol was modified on the COFs via a simple click chemistry reaction to construct a novel stationary phase material named COF-S-C18. The successful synthesis of the COF-S-C18 material was verified by various characterization methods such as elemental analysis (EA), thermogravimetric analysis (TGA), and water contact angle measurement. Compared with the COFs column, the COF-S-C18 packed column enabled efficient separation of eight hydrophobic compounds. Experimental results demonstrated that the as-synthesized stationary phase exhibited excellent separation selectivity, stability, and reproducibility. Furthermore, the COF-S-C18 and commercial C18 columns were used to determine bisphenol A (BPA) from supermarket receipts. The detected BPA contents were 0.03036 mg g⁻¹ and 0.02992 mg g⁻¹, respectively, with a relative deviation of 1.5 %. These findings confirm that the novel COF-S-C18 stationary phase holds great application potential for the analysis of real samples. This work offered a novel idea for the development of COFs-based chromatographic stationary phases and expanded the application.