Comparison of elution strength, column efficiency, and peak symmetry in subcritical water chromatography and traditional reversed-phase liquid chromatography

In this study, the elution strength of subcritical water has been investigated by matching the retention times of catechol, aniline, and pyridine using subcritical water, acetonitrile-ambient water, or methanol-ambient water mixtures as the eluent. Separations were performed on Chromatorex C-18, Zorbax RX-C-18, and poly(styrene-divinylbenzene) columns. The separation temperature ranged from 60 to 200 degreesC depending on columns used. It was found that a temperature rise of 40 degreesC for pure water mobile phase resulted in shortening retention time of at least the last eluting solute in each mixture by approximately 50%. The column efficiency study showed that subcritical water separation was more efficient than traditional separations using organic solvent-ambient water mixtures on the PRP-1 column. When temperature was increased, peak symmetry in subcritical water separation was mostly improved. This tendency was observed for separations on all three columns. (C) 2003 Published by Elsevier B.V.