The Thermodynamics of Chromatography - Other Thermodynamic Methods that are Used for Studying Chromatographic Systems > Optimum Operating Conditions for Chiral Separations in Liquid Chromatography > Page 62



It is clear, that the optimum conditions for any given LC analysis (those conditions that will produce a separation in the minimum time) can be very complex. In addition, this complexity will be greater the more difficult the separation. In the first instance, there will be an optimum temperature and optimum solvent composition that will provide the optimum capacity ratios and separation ratios for a given chiral pair. Added to that, the analysis time will depend on the column length which, in turn, will be determined by the minimum efficiency requirement. Furthermore, as the necessary efficiency is a complex function of both the separation ratio of the chiral pair and theircapacity ratios,the optimum solvent composition and temperature will not necessarily be those that provide the maximum separation ratio and/or the minimum capacity ratios.

In LC, when employing a binary mixture of solvents as the mobile phase, the corrected retention volume (V'a) of a substance (a) is generally defined by the following equation,


where (T) is the absolute temperature
and (c) is the volume fraction of one component of the mobile phase