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 (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.