Polymer-based stationary phases

Organic Polymer-based Stationary Phase Materials... 

Surface-modified silica gels are used for a variety of separations, but organic polymer-based stationary phase materials are more useful for long-term operations, such as for an amino acid analyser and size-exclusion liquid chromatography. 

The disposal of used stationary phase materials, especially those used for biomedical applications, should also be of concern. Silica gel-based stationary phase materials can be heated at high temperature before disposal, and organic polymer-based stationary phase materials can be burned. Take care. 

Meyer, C., Skogsberg, U., Welsch, N., and Albert, K., Nuclear magnetic resonance and high-performance liquid chromatographic evaluation of polymer-based stationary phases immobilized on silica. Anal. Bioanal. Chem., 382, 679, 2005. 

The usual base materials for LC restricted-access media are porous silica supports, which limit the pH range of the mobile phases to 2-8. Polymer-based stationary phases have also been used as restricted-access media and are character-... 

Ion suppression is not often applied to strong acids or strong bases because of the extremes in pH that would be required for retention. Suppression by the addition of buffers is restricted to the range pH 3-8, because silica-based stationary phases are unstable in solutions of either high or low pH (i.e., above pH 8 or below pH 2). These restrictions do not apply to polymeric supports, and polymer-based stationary phases can be used in the separation of a wider range of solutes using the ion-suppression technique. 

Polymer-based stationary phases suffer from lower mechanical resistance, even if their pH stability is impressive. The following section focuses on the physical description of silica-based adsorbents since they are the most conunon. 

As early as in the 1950s separations were described that utilised ion-exchange resins for separation of non-ionic organic substances, principally on the basis of a reversed-phase mechanism [50[. Since then, sufficiently rigid, chemically and mechanically stable polymer-based stationary phases have been introduced having a broad range of particle sizes and porosities which are comparable to silica-based stationary phases. Most... 

Polydivinylbenzene and polystyrene polymer based stationary phases also eliminate these effects. Porous graphitic carbon provides a highly non-polar surface with excellent chemical stability under acidic and basic conditions. However, they suffer from lower sample loading capacity and lower efficiency than conventional columns. 

Tanaka, N., Hashizume, K. and Araki, M. Comparison of polymer-based stationary phases with silica-based stationary phases in reversed-phase liquid chromatography, J. Chromatogr., 1987, 400, 33-45. 

Jedrejewski, P.T. Taylor, L.T. Comparison of silica-, alumina-, and polymer-based stationary phases for reversed-phase liquid chromatography. J.Chromatogr.ScL, 1995, 33, 438-445... 

Haginaka, J. Takehira, H. Hosoya, K. Tanaka, N. Molecularly imprinted uniformsized polymer-based stationary phase for naproxen. Comparison of molecular recognition ability of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques. J. Chromatogr. A 1998, 816, 113-121. 

Hosoya, K. Yoshizako, K. Shirasu, Y. Kimata, K. Araki, T. Tanaka, N. Haginaka, J. Molecularly imprinted uniform-size polymer-based stationary phase for high-performance hquid chromatography. Structural contribution of cross-linked polymer network on specific molecular recognition. J. Chromatogr. A 1996, 728,139 148. 

In Figure 2.11, the separation of seven alkylphenones on a polymer-based stationary phase over the temperature range from 30 to 100 C is shown. Three effects can be seen from this figure ... 

The three considerations above clearly show that the example of alkylphenones on a polymer-based stationary phase showthe Hmitations of this particular application. Nevertheless, the use of temperature to speed up separation is, in spite of the discussed limitations, always worth a consideration. If method selectivity and the instrument capabihties allow for this, there are few reasons not to operate at temperatures of about 50 °C to allow for the advantages of reduced analysis times to be observed. To speed up a method by using elevated temperature, three important considerations must be made ... 

Technological developments of various sorts are presented. Chapters deals with new packings based on derivatized silica. Modern polymer-based stationary phases especially designed for biopolymer separations are described in Chapter 9. The application of on-line light-scattering detectors to such separations is described in Chapter 12. 

K. Hosoya, K. Yoshizako, N. Tanaka, K. Kimata, T. Araki and J. Haginak, Uniform-size Macroporous polymer-based stationary phase for HPLC prepared through molecular imprinting technique, Chem. Lett., 23 (8) 1437-1438,1994. 

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