Relationship between retention of a solid solute in liquid and supercritical fluid chromatography and its solubility in the mobile phase

Abstract

An inverse relationship is derived between solubility and chromatographic retention and tested for five polyaromatic compounds using supercritical fluid chromatography (SFC) and high-performance liquid chromatography (HPLC), measured liquid solubilities and published supercritical fluid solubilities. For both the SFC and HPLC measurements the same column was used with an octadecylsilyl bonded stationary phase, and as mobile phases carbon dioxide, at pressures between 70 and 250 bar, and methanol–water were used, respectively. Solubilities were obtained from UV absorption of the diluted saturated solutions, and solubility and retention measurements were carried out between 308.2 and 328.2 K. The relationship is found to hold well for naphthalene in both SFC and HPLC and for the other compounds in SFC. Implications for the rapid measurement of solubility by chromatography are discussed.