Carbon dioxide retention model

Berge and Deye studied the effect of column surface area on the retention of polar solutes [18]. They found that there was a linear relationship between retention and the surface area. 4-Hydroxy benzoic acid was used as a model acidic compound, and sulfamethazine, sulfanilamide, sulfi-somidine, and sulfapyridine were used as the model basic compounds. The separations were carried out on a packed Nucleosil Diol column with a methanol-modified carbon dioxide as the mobile phase. The UV detector was used for the analysis. It was observed that 0.1% acetic acid for the acidic solutes and 0.1% isopropylamine for basic solutes was required in the methanol to achieve the separations. The efficiency was found to be similar for 100-, 300-, and 500-A packing materials. 

Figure 7.7. System constants of the solvation parameter model for retention on a porous polymer stationary phase with a binary mixture of carbon dioxide and 1,1,1,2-tetrafluoroethane as the mobile phase. Column 25 cm X 4.6 mm I.D. Jordi-Gel RP-C18 with a 5 pm average particle diameter. The total fluid flow rate was 1.0 ml/min, backpressure 200 bar and ternperamre I25°C.

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