Carboxyl modified magnetic nanoparticles coated open tubular column for capillary electrochromatographic separation of biomolecules

Carboxyl modified magnetic nanoparticles (Fe3O4-COOH MNPs) coated open tubular (OT) columns were prepared for capillary electrochromatography. The Fe3O4-COOH MNPs coatings were constructed on the surface of positively charged poly(diallydimethylammonium chloride) (PDDA) modified capillaries through electrostatic self-assembly approach. The as-prepared PDDA@Fe3O4-COOH MNPs coated OT columns were characterized by scanning electron microscopy and electroosmotic flow measurement. The electrochromatographic characterization of the OT columns was evaluated by separation of amino acids, dipeptides and proteins. The influences of background solution pH, concentration, and organic modifier content on separation were investigated. The separation of these analytes was primarily based on the electrophoretic mechanism in combination with chromatographic mechanism. The Fe3O4-COOH MNPs coatings improved the separation resolution of these analytes due to their large surface area. Three variants of bovine serum albumin, two variants of β-lactoglobulin and nine glycoisoforms of ovalbumin were successfully separated. The relative standard deviations of migration times of analytes representing run-to-run, day-to-day and column-to-column were less than 4.3%. Furthermore, the feasibility of the PDDA@Fe3O4-COOH MNPs coated OT column was verified by successful separation of acidic proteins in egg white.