Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols

Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal–organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10   min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5   mL   min −1 . The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000   plates   m −1 for δ-tocopherol) and good precision (0.2–0.3% for retention time, 1.8–3.4% for peak area, 2.6–2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences.