The Thermodynamics of Chromatography - Other Thermodynamic Methods that are Used for Studying Chromatographic Systems > Optimum Operating Conditions for Chiral Separations in Liquid Chromatography > Effect of Temperature and Solvent Composition on the Optimum Velocity > Page 83

Figure 26. Curves Relating Analysis Time to Temperature for Different Solvent Mixtures

It is seen that the exact opposite conditions to those indicated by the optimum mobile phase velocities provide the minimum analysis times i.e., low temperatures and solvents of minimum polarity. This is because under these conditions very high capacity ratios are realized accompanied by relatively large separation ratios. Large capacity and separation ratios require relatively low column efficiencies to affect a separation and, consequently, only relatively short columns are required. The columns can, in fact be so short that, even with relatively low mobile phase velocities that these conditions evoke, the analysis times are still very small.