The relationships between the plate height HETP and the linear mobile phase velocity u in supercritical fluid chromatography (SFC) were investigated over a wide range of experimental conditions (pressure p = 8. 5 ∼ 15 MPa, temperature T = 35 ∼ 45°C) with carbon dioxide as the mobile phase. When the HETP - u curves were converted into the dimensionless variables h = HETP/d
p and ν = ud
p/D
m, the curves were similar regardless of the pressure, the temperature and the state of the mobile phase. The distribution coefficient K decreased with increasing T and/or p. The K values were correlated to the mobile phase density. A linear increase of the pressure was applied to elute the sample from the column. The result was simulated by a chromatography model with the isobar chromatography data. These results have shown that the separation behavior of SFC at low sample loadings can be predicted by ordinary liquid chromatography models. Further research should be done for the prediction of the separation behavior at overloaded conditions.
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