An empirical approach for predicting retention characteristics in supercritical fluid chromatography

The retention process in supercritical fluid chromatography depends on the solute volatility as well as the strength of the mobile phase. When the capacity factor is plotted as a function of temperature at constant pressure, the curve passes through a maximum point. At higher temperatures, the capacity factor decreases as the temperature increases, and at lower temperatures the opposite is observed. This makes prediction of the capacity factor in supercritical fluid chromatography complicated. Rigorous thermodynamic equations to predict retention characteristics result in complex equations. A simple empirical approach for prediction of the capacity factor as a function of mobile phase density and column temperature is presented.