In situ room-temperature preparation of a covalent organic framework as stationary phase for high-efficiency capillary electrochromatographic separation.

Covalent organic frameworks (COFs), considered as a series of newly emerging porous organic materials, have been widely utilized in separation fields. Herein, a novel COF (TFPB-BD) was first employed as stationary phase for high-efficiency capillary electrochromatographic separation. Benzidine (BD) and 1,3,5-Tris-(4-formylphenyl)benzene (TFPB) were selected as organic linkers and then introduced into the aldehyde group modified capillary for the in situ growth of TFPB-BD onto the capillary inner wall at room temperature. The morphology and formation of TFPB coated capillary column were confirmed by a variety of tools including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). It's interesting that the TFPB globular crystals with nanoscale were uniformly and densely modified on the capillary inner surface. Hence, the prepared column exhibited prominent separation performance for the test analytes including alkylbenzenes, chlorobenzenes and phenolic compounds with high efficiency and high resolution. The maximum column efficiency can reach about 1.8 × 105 plates•m-1. Additionally, the high resolutions of anilines, amino acids and parabens were also achieved on the TFPB modified capillary. The precisions (RSDs) of the retention times of alkylbenzenes of intra-day runs (n = 3), inter-day runs (n = 3) and parallel columns (n = 3) were all less than 2.83%. This innovative COF-based stationary phase gives great promise for the chromatographic separation field.