The high efficient separation of divinylbenzene and ethylvinylbenzene isomers using high performance liquid chromatography with Fe-based MILs packed columns

- The baseline separation of divinylbenzene and ethylvinylbenzene isomers was achieved on the Fe-based MILs as liquid chromatographic columns for the first time.
- The separation performances and mechanisms of the two Fe-based MILs for divinylbenzene and ethylvinylbenzene isomers were deeply discussed.
- The pore sizes and structures of the Fe-based MILs significantly affect the separation efficiency.

The baseline separation of divinylbenzene (DVB) and ethylvinylbenzene (EVB) isomers was achieved using HPLC with MIL-53(Fe) and MIL-100(Fe) packed columns respectively when hexane/dichloromethane (100:0) used as mobile phase, at flow rate of 0.5 mL min−1, room temperature, and monitored with a UV detector at 254 nm. The two Fe-based MILs packed columns showed different separated performances, analytes had short retention time on MIL-100(Fe) compared to MIL-53(Fe), but selectivity of DVB isomers (m-DVB and p-DVB) was lower, which was mainly due to the differences of the pore size and structure of MILs. Moreover, the results of calculated thermodynamic parameters showed that the separation of DVB and EVB isomers was not only controlled by enthalpy change (ΔH), but also controlled by entropy change (ΔS). The head-to-tail stacking was the main reason for the separation according to the mechanism of the DVB and EVB isomers on Fe-based MILs packed columns.