Unusual pressure-temperature dependency in the capillary liquid chromatographic separation of C8 alkylaromatics on the MIL-53(Al) metal–organic framework

The propagation of C8 alkylaromatics (in particular ethylbenzene (EB), p-xylene (pX) and o-xylene (oX)) through MIL-53(Al) packed capillaries at varying temperatures (from 20 to 70 °C) and mobile phase compositions of acetonitrile/1-propanol (75/25, 50/50 and 25/75) has produced unexpected trends in retention behavior and pressure drop; these effects are attributed to framework breathing. Thereby, it seems feasible to perform these chromatographic separations on MIL-53(Al) at elevated temperatures, resulting in much smaller analysis times without losing too much selectivity.

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► MIL-53(Al) packed in capillary column.
► Separation of xylene isomers in liquid phase chromatography.
► Pressure drop over column increases with temperature due to framework breathing.