Supercritical fluid chromatography: Retention, resolution, and gradient methods

Summary For applying gradient methods in supercritical fluid chromatography (SFC), the dependence of retention and resolution on the physical parameters, temperature, pressure/density, linear velocity, and mobile phase composition, is of particular relevance. This stems from the finding that the dependence of retention and resolution on physical parameters is more varied for SFC than for either gas or liquid chromatography. Thus, both retention and resolution tend to form maxima with temperature at constant pressure. In this communication, the dependence of capacity ratio k and resolution R on temperature and pressure is shown as three-dimensional plots. From these plots the general requirements for single and multiple gradients are discussed. In addition, equations are given which relate the contributions of vapor pressure and solvation to the measured capacity ratio k and selectivity .

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Chromatographie mit überkritischen fluiden Phasen: Retention, Auflösung und Gradientenmethoden