Preparation of D-histidine modified zeolitic imidazolate framework-90 coated capillary column and its application in open-tube capillary electrochromatography enantioseparation.

Metal-organic framework materials are a class of novel crystalline porous materials with regular pore structures formed by covalent bonding between metal centers and organic functional groups. Metal-organic framework materials have attracted great interest in analytical chemistry due to their unique properties such as good stability and permanent porosity. In this work, D-histidine was used to carry out chiral modification of zeolitic imidazolate framework-90 under mild conditions, and the D-histidine modified zeolitic imidazolate framework-90 coated capillary column was prepared. This chiral capillary column was used to separate epinephrine, norepinephrine, terbutaline, and tryptophan enantiomers. Under optimum conditions, baseline separations were achieved. The intra-day, inter-day, and inter-column relative standard deviations (n = 3) of the four pairs of enantiomeric migration times were 0.15%-0.56%, 0.74%-2.40%, and 1.93%-3.18%, respectively. Moreover, the D-histidine modified zeolitic imidazolate framework-90 coated capillary could be reused for at least 150 runs without significant changes in the separation efficiency and migration time.