Hybrid methacrylate monolithic columns containing magnetic nanoparticles for capillary electrochromatography

Vinylized iron oxide magnetic nanoparticles (VMNPs) were incorporated into polymethacrylate monolithic columns to develop novel stationary phases with enhanced separation performance. The VMNPs were dispersed in a polymerization mixture containing gycidyl methacrylate and ethylene glycol dimethacrylate as monomers, cyclohexanol and 1-dodecanol as porogens and azobisisobutyronitrile as initiator. The stability of the VMNPs in the polymerization mixture was investigated at several VMNP contents. Using short UV-polymerization times, polymeric beds with homogenously dispersed VMNPs were obtained. The novel stationary phases were characterized by scanning electron microscopy. The chromatographic performance of these hybrid monoliths was evaluated using alkyl benzenes and organophosphorous pesticides as test solutes. Using capillary electrochromatography, efficiencies up to 130,000 plates/m were achieved. The increase of the specific surface area of hybrid monoliths led to an increase in the retention of all the test analytes, and an enhancement of efficiency. The resulting hybrid monolithic columns exhibited satisfactory column to-column and batch-to-batch reproducibilities with RSDs values below 6%.