(218b) Green Separations with Superheated Water: Understanding the Retention Mechanism in Reversed-Phase Liquid Chromatography

Green Separations with Superheated Water: Understanding the Retention Mechanism in Reversed-Phase Liquid Chromatography

Rebecca K. Lindsey,¹ Mark R. Schure,² and J. Ilja Siepmann^1,3†

¹Department of Chemistry and Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431
²Theoretical Separation Science Laboratory, Kroungold Analytical Inc., 1299 Butler Pike, Blue Bell, PA 19422
³Department of Chemical Engineering and Materials Science University of Minnesota, Minneapolis, MN 55455-0431

As chemistry moves towards a more “green” approach, separation scientists look to superheated water as an alternative for the water/(methanol or acetonitrile or tetrahydrofuran) solvent mixtures ubiquitous in reversed-phase liquid chromatography (RPLC). It has been shown that under heat and compression, water loses its highly lipophobic character, preventing the overly long retention times associated with a neat water mobile phase in RPLC at near-ambient conditions. Configurational-bias Monte Carlo simulations in the Gibbs ensemble are employed to study the separation of small alkanes and primary alcohols in a model RPLC system with a hot, compressed water mobile phase. Additional simulations are carried out for the bulk n-hexadecane/water system to examine the extent to which retention in these systems can be characterized by a partitioning mechanism.

^† Corresponding Author E-mail: siepmann@umn.edu