CHROMATOGRAPHY, Vol. 30 (2009), No. 1, pp. 1-9
Focusing Review
Development of Novel Thermally Responsible Separation Systems using Functional Polymers
Hideko Kanazawa
Faculty of Pharmacy, Keio University
1-5-30 Shibakoen, Minato-ku, Tokyo 105-8512, JAPAN
We have been investigating a new concept of chromatography, a temperature.responsive chromatography, using a temperature.responsive poly (N-isopropyl acrylamide) (PNIPAAm) modified surface for the packing materials of chromatography. PNIPAAm-grafted surfaces showed temperature-responsive hydrophilic-hydrophobic surface-property alterations. Using these features, PNIPAAm and related temperature- responsive polymers have been used to generate temperature-sensitive stationary phases for chromatographic systems. We modified several different functional polymers to silica beads, including temperature and pH-responsive polymers. Temperature-dependent chromatographic interactions with soluble analytes were modulated by changing the grafted PNIPAAm chain property with a constant aqueous media as the mobile phase. These temperature-responsive stationary phases may be useful for method development as an extra tool to optimize the selectivity by adjusting the temperature. The applications of thermally responsive columns have been demonstrated for separations in the HPLC mode. Temperature-responsive chromatography is performed with an aqueous mobile phase without using an organic solvent, such as methanol or acetonitrile, which are used in reverse.phase LC. We achieved temperature.dependent separations of steroids and amino acids using only water as a mobile phase on the PNIPAAm-modified column. Temperature-responsive chromatography could achieve the separation of proteins under mild elution conditions, such as a physiological condition. Thus, temperature.responsive chromatography which can change the properties for HPLC by changing only the column temperature have advantages in maintaining the biological activity of proteins and in reduced pollution from an organic solvent. The preparation of these stationary phases and their many smart applications are reviewed here.
Keywords: Poly (N-isopropylacrylamide); temperature-responsive chromatography; functional polymer; environmental-responsive polymer.