Organic Polymer-based Stationary Phase Materials

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. 

Conditions columns, Asahipak GS320 (vinyl alcohol copolymer gel), 50 cm x 7.6 mm i.d. eluent, 0.1 M sodium phosphate containing 0.3 M sodium chloride pH 7.0 flow rate, 1 ml min-1 detection, UV 250 nm direct injection of sample. Peaks l, protein, 2, orotidine 3, creatinine, and 4, uric acid. 

These separations can be carried out using a silica-based bonded phase however, the important advantage of organic polymer stationary phase materials is their chemical stability. The columns can be washed by using an alkaline solution after a certain number of injections. According to the chromatograms, the proteins in serum are completely eluted and nothing remains inside the column. However, the pressure drop in this type of analysis 

The separation of basic and metal-sensitive compounds is difficult on silica-based stationary phase materials, but these separations can be performed on vinyl alcohol copolymer gels. Examples are the separation of methallothionein from dolphin kidney, a-, j8-, and y-endorphin, and nucleotide and nucleoside mixtures.8 However, an analytical-scale separation may also be performed on surface-modified wide-pore silica gels (pore size 300 A or more), using columns which showed a negative response in the heavy metal test described above. 

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Organic Polymer-based Stationary Phase Materials... 

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. 

Polystyrene/divinylbenzene-based ion-exclusion columns are also offered by Hamilton Co. (Reno, NV, USA) under the trade name PRP-X300. This is a 10-pm material with an exchange capacity of 0.2 mequiv/g [4], It is obtained by sulfonation of PRP-1, a macroporous PS/DVB polymer with reversed-phase properties. Fig. 4-2 shows the separation of various organic acids on this stationary phase. Dilute sulfuric acid was used as the eluent. The much higher retention of succinic acid compared to acetic acid reveals that the retention of organic acids is chararcterized, apart from reversed-phase effects, by the formation of hydrogen bonds. 

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