Preparation and Application of Microporous Core–shell ZIF-8@UiO-66-NH₂ Composite As High-performance Stationary Phase in Capillary Electrochromatography

In this study, the octahedral core–shell ZIF-8@UiO-66-NH₂ composite, exhibiting high crystallinity, microporous structural properties and multifunctional groups, was synthesized, characterized, and applied for the first time as stationary phase in capillary electrochromatography. The baseline separation of four groups containing 14 analytes was achieved within 11.6 min, with resolution of at least 1.51. Compared to the individual components of ZIF-8 and UiO-66-NH₂ used as chromatographic stationary phase, the bonded capillary column based on ZIF-8@UiO-66-NH₂ exhibited the improvement in resolution and column efficiency (theoretical plate numbers) ranging from 68.14 to 918.75% and from 3.92 to 398.31%, respectively, and sample loading capacity increased by ≥ 26.8%. Furthermore, an accurate, rapid, and reliable electrochromatography method was developed for the qualitative and quantitative analysis of thiamphenicol and florfenicol in pork meat. The limits of detection and quantification for thiamphenicol were 0.34 μg/mL and 1.75 μg/mL, and for florfenicol, 1.00 μg/mL and 5.82 μg/mL, with sample recoveries in the range of 96.00 to 108.00% and the standard deviations less than 4.59%. This work not only confirmed the potential of MOF@MOF composite as high-performance stationary phases but also broadened the electrochromatography application in food inspection.