Carboxymethyl-β-cyclodextrin and histidine-zeolitic imidazolate framework-8 used for enantioseparation of three basic drugs in open-tubular capillary electrochromatography.

Metal organic frameworks (MOFs) have drawn broad attention as a novel stationary phase due to their highly porous structure, modifiable pores, large specific surface areas, and satisfactory stability. In this paper, histidine-zeolitic imidazolate framework-8 (His-ZIF-8) synthesized at room temperature was physically coated to the internal surface of the capillary column and the carboxymethyl-β-cyclodextrin (CM-β-CD) as the chiral selector was chemically bonded to the His-ZIF-8@capillary column. The prepared CM-β-CD@His-ZIF-8@capillary column was used for the enantioseparation of amlodipine, propranolol, and atenolol in capillary electrochromatography. In contrast to the CM-β-CD@capillary column without His-ZIF-8, the CM-β-CD@His-ZIF-8@capillary column reveals significantly improved enantiodiscrimination performance for amlodipine (R : 0 → 2.29), propranolol (R : 0 → 1.69), and atenolol (R : 0 → 0.79). His-ZIF-8 concentration, buffer pH, buffer concentration, and the proportion of organic modifier were evaluated in detail with enantiomerically separating chiral molecules. The repeatability of intraday, day-to-day, and column-to-column have been discussed; the result was preferable, and the relative standard deviation (RSD) of separation parameters was <6.7%.