Reverse-phase high performance liquid chromatography separation of positional isomers on a MIL-53(Fe) packed column

The application of the metal–organic framework (MOF) MIL-53(Fe) as a novel stationary phase for reverse-phase high performance liquid chromatography (HPLC) separation of positional isomers is described for the first time. Under the optimized conditions, baseline separation of xylene, dichlorobenzene, chlorotoluene and nitroaniline isomers was achieved on the MIL-53(Fe) packed column within a short time. The retention mechanisms of these isomers on the MIL-53(Fe) packed column were discussed in detail, and a typical reverse-phase behavior can describe the results. The thermodynamic characteristics of the HPLC separation of positional isomers were also evaluated. It was confirmed that the HPLC separation of positional isomers was controlled by the Gibbs free energy change (ΔG). In addition, reverse-phase HPLC separation of the tested isomers was also carried on MIL-53(Al, Cr) packed columns to investigate the influence of the metal centre of the MIL-53 framework on their chromatographic behaviors. The results showed that the MIL-53(Fe) packed column exhibited better separation performance than the MIL-53(Al, Cr) packed columns. Moreover, the MIL-53(Fe) packed column also gave efficient HPLC separation of alkylbenzene and naphthalene, aniline compounds and polycyclic aromatic hydrocarbons (PAHs). These successful applications suggest the potential of MIL-53(Fe) as a novel stationary phase for efficient reverse-phase HPLC separation.