L-Cys-functionalized Zr-based MOF NU-1000: Fabrication and application as chiral stationary phase in open tubular capillary electrochromatography for chiral separation

Metal-organic frameworks (MOFs) are promising chiral separation materials owing to their well-defined pore structures and tunable functionality. In this work, mesoporous/microporous NU-1000 was functionalized with L-Cysteine (L-Cys) via solvent-assisted ligand exchange to produce L-Cys-NU-1000, which was applied as a stationary phase in capillary electrochromatography (CEC). The resulting L-Cys-NU-1000@capillary system achieved baseline separation of five chiral amino acid enantiomers with excellent intra-day, inter-day, and batch reproducibility (RSDs < 5%). Notably, the system retained high enantioselectivity even after 100 consecutive injections. This study represents the first application of NU-1000 in chiral separation, opening new avenues for its use and laying a foundation for broader future applications. The system demonstrates distinct advantages for quality control of amino acids, offering high efficiency, robustness, and reproducible enantiomeric separation crucial for food and pharmaceutical analysis.