Superheated water as eluent in high-temperature high-performance liquid chromatographic separations of steroids on a polymer-coated zirconia column

High-temperature liquid chromatography (HTLC),;with a superheated water mob ile phase, has been shown to be a feasible replacement for medium-polarity acetonitrile-water mixtures as an eluent in reversed-phase HPLC, instrument al parameters of flow-rate, injection volume and mobile phase preheating we re shown to have significant effects on the quality of the chromatographic peaks. The selectivity and retention patterns of testosterone and several r elated compounds were investigated on a porous zirconia, polybutadiene-coat ed column at temperatures up to 200 degreesC and compared with that of a po rous silica, octadecylsilane-coated column and the zirconia column under tr aditional reversed-phase conditions of an acetonitrile-water mobile phase a t 40 degreesC. The selectivity differences observed for testosterone and re lated compounds show that the separation mechanisms are complementary and u nique selectivity is obtained with the zirconia column under HTLC condition s. (C) 2001 Elsevier Science B.V. All rights reserved.