Preparation of low flow-resistant methacrylate-based monolithic stationary phases of different hydrophobicity and the application to rapid reversed-phase liquid chromatographic separation of alkylbenzenes at high flow rate and elevated temperature

作者：Ueki Y; Umemura T^*; Iwashita Y; Odake T; Haraguchi H; Tsunoda K

来源：Journal of Chromatography A, 2006, 1106(1-2): 106-111.

DOI：10.1016/j.chroma.2005.08.041

• monolithic column
• octadecyl methacrylate
• reversed-phase capillary liquid chromatography
• flow rate gradient

Low flow-resistant alkyl methacrylate-based monolithic stationary phases of different hydrophobicity were constructed for reversed-phase capillary liquid chromatography by thermally initiated radical polymerization of respective methacrylate ester monomer with different alkyl chain (C2, C4, C6, C12, C18) and ethylene glycol dimethacrylate (EDMA) in a 250 Lrn i.d. fused silica capillary. The hydrophobicity was basically controlled by changing the length and/or the density of the alkyl-chain, while the composition and the ratio of porogenic solvent were adjusted to obtain highly permeable rigid monoliths with adequate column efficiency. Among the prepared monolithic stationary phases, C18-methacrylate monoliths polymerized from a binary porogenic solvent of isoamyl alcohol and 1,4-buthandiol exhibited the most promising performance in terms of hydraulic resistance and column efficiency. The pressure drops of 20-cm long monolithic columns were below similar to 0.4MPa at a normal linear velocity of 1 mnVs (a flow rate of 3 mu L/min), and the numbers of theoretical plates for alkylbenzenes mostly exceeded 3000 plates/20-cm. The produced monolithic columns had good mechanical strength for high pressure and temperature, and could be properly operated even at a temperature of 80 degrees C and at a pressure of at least 33 MPa. At 80 degrees C, the theoretical plate numbers reached 6000 plates/20 cm because of the enhanced mass transfer. Due to the novel hydraulic resistance and mechanical strength, the separation time could be reduced 120-fold simply by raising the flow rate and column temperature.

• 出版日期2006-2-17