Capillary Electrochromatography on Methacrylate Based Monolithic Columns: Evaluation of Column Performance and Separation of Polyphenols |
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Authors: | A Messina C Desiderio A De Rossi F Bachechi M Sinibaldi |
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Institution: | (1) Dipartimento di Chimica, Università di Roma ``La Sapienza', Pl. Aldo Moro, 5, Rome, Italy;(2) CNR Istituto di Metodologie Chimiche, Area della Ricerca di Roma1, Rome, Italy;(3) CNR Istituto di Cristallografia, Area della Ricerca di Roma 1, Rome, Italy;(4) CNR – Istituto di Metodologie Chimiche, Sezione Meccanismi di Reazione, c/o Dipartimento di Chimica, Università di Roma “La Sapienza”, Pl. Aldo Moro 5, I-00185 Rome, Italy |
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Abstract: | Fused-silica capillary columns (100 µm I.D.) englobing a porous monolithic stationary phase were prepared by in situ copolymerization of 2-ethylhexyl methacrylate, ethylene glycol dimethacrylate and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in the presence of a porogenic mixture containing 1-propanol, 1,4 butanediol and water. The influence of the monomers ratio and the porogen solvent composition as well as the content of AMPS in the polymerization mixture on column total porosity and efficiency was investigated to attain minimum HETP values for the reversed-phase capillary electrochromatography separation of bioflavonoids. For the most promising column, the van Deemter plots, in both μ-HPLC and CEC, were also evaluated. In CEC the reduced plate height was found almost constant (1.6–2.0) within the range of linear mobile phase velocity between 0.2–2.0 mm s?1. The chemical and mechanical stabilities of the monolithic column over a wide range of buffer pH (2-10) and time were satisfactory. Furthermore, the effects of mobile phase parameters, such as buffer concentration and organic modifier content, on the electroosmotic flow were studied systematically. CEC separations of standard mixtures of polyphenols, including flavonols, flavanones and flavanones-7-O-glycosides, were accomplished in less than 8 min. The CEC separation of the major flavanone glycoside constituents in the extract from a freshly squeezed grapefruit juice was also reported. |
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Keywords: | Capillary electrochromatography Monolithic columns Polymethacrylates Reversed-phase separation Bioflavonoids |
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