Layer-by-layer assembly of zeolite imidazolate framework-8 as coating material for capillary electrochromatography

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Open-tubular capillary columns are crucial for chromatographic separations.
• Zeolite imidazolate frameworks (ZIFs) offer tunable properties for advanced materials.

Purpose of the Study:

• To develop and evaluate a novel open-tubular capillary column coated with ZIF-8 nanocrystals for capillary electrochromatography.
• To investigate the separation capabilities for phenolic isomers using this ZIF-8 coated column.

Main Methods:

• Preparation of ZIF-8 coated capillary columns using a layer-by-layer method on fused silica.
• Evaluation of column performance using open-tubular capillary electrochromatography.
• Optimization of separation parameters including pH, buffer concentration, and applied voltage.

Main Results:

• Achieved good separation of nine phenolic isomers, attributed to strong interactions between unsaturated Zn sites and phenols.
• Demonstrated high column efficiency for o-nitrophenol (208,860 plates/m).
• Exhibited excellent reproducibility for retention time and resolution of nitrophenol isomers (RSDs < 6.5%).

Conclusions:

• The ZIF-8 coated capillary column is effective for separating phenolic compounds.
• The developed method offers high performance and reproducibility for capillary electrochromatography applications.