Capillary coated with three-dimensional covalent organic frameworks for separation of fluoroquinolones by open-tubular capillary electrochromatography

The Schiff-base reaction of 1,3,5-triformylphloroglucinol (Tp) and tetra(4-aminophenyl)methane (TAM) was performed for the synthesis of a three-dimensional covalent organic framework named 3D TpTAM, which was obtained by an ultrasound-assisted method for the first time. The morphology and structure of the synthesized TpTAM were characterized through various methods. Then, TpTAM-coated capillary columns were subsequently prepared by a covalent bonding method within a short time and applied for the separation of fluoroquinolones by capillary electrochromatography (CEC) with good resolution and reproducibility. The intraday relative standard deviations (RSDs) of the retention time and peak areas were 0.88%-0.95% and 2.27%-3.81%, respectively. The interday RSDs of retention time and peak areas were 0.71%-0.89% and 0.88%-3.60%, respectively. The column-to-column RSDs of retention time and peak areas were less than 1.90% and 13.56%, respectively. The interbatch RSDs of retention time and peak areas were less than 3.48% and 3.89%, respectively. The TpTAM-coated capillary columns could be used for no less than 100 runs with no observable changes in the separation efficiency. The separation mechanism was also studied, which indicated that pi-pi stacking effects, hydrophobic interactions and hydrogen bonding were the main factors. The results revealed that 3D TpTAM should have superior potential as the stationary phase in CEC for chromatographic separation. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A three-dimensional covalent organic framework 3D TpTAM was successfully synthesized via Schiff-base reaction and ultrasound-assisted method, and TpTAM-coated capillary columns were prepared for the separation of fluoroquinolones by capillary electrochromatography with high resolution and reproducibility. The column showed good stability and could be used for more than 100 runs without noticeable changes.