Fluorinated covalent triazine frameworks as stationary phase for the separation of fluorinated compounds by capillary electrochromatography

Abstract

Three covalent triazine frameworks (CTFs) named as H-CTF, TF50-CTF and TF-CTF, containing different numbers of fluorine atoms were constructed to serve as stationary phases for capillary electrochromatography (CEC), and fluorine interactions were investigated by changing the number of fluorine atoms in the stationary phases and separating the targeted analytes. The developed CEC column was used to separate fluoroquinolones (FQs), β-phenylalanine and trifluoromethyl β-phenylalanine analogs. Characterization of the materials and the electrochromatographic columns revealed that the materials were successfully synthesized and that the inner surfaces of the capillary columns were uniformly coated with CTFs. The evaluation of the TF-CTF-coated capillary column proved that it had good resolution and reproducibility. The intraday relative standard deviations (RSDs) of the retention time (n = 9) and peak area were 0.72 %-0.85 % and 1.19 %-2.60 %, respectively. The interday RSDs (n = 9) of the retention time and peak area were 0.85 %-1.06 % and 2.59 %-3.68 %, respectively. The column-to-column RSDs of the retention time (n = 9) and peak area were 0.54 %-0.69 % and 2.95 %-4.55 %, respectively. The interbatch RSDs of the retention time and peak area (n = 9) were 2.11 %-2.89 % and 2.74 %-6.46 %, respectively. A comparsion of the peak order of fluorinated compounds in the same stationary phase and the separation efficiency of three stationary phases relative to the same target substance, it demonstrated that fluorine interaction can improve the separation efficiency of CEC.