Abstract
In supercritical fluid chromatography (SFC), the permanent chemical modification of a silica stationary phase which occurs when eluent mixtures containing 1,4-dioxane are used leads to decreased retention with ethane and carbon dioxide as the mobile phases. Contrary to ethane, with carbon dioxide improved resolution is obtained on the dioxane-modified silica stationary phase. The chromatographic parameters capacity factor, selectivity, and mean resolution for a test mixture of aromatic compounds showed maxima as a function of temperature. The intensity of these maxima decreased with increasing pressure and increasing amount of 1,4-dioxane in mixtures with carbon dioxide or ethane. Furthermore, their positions were shifted to higher temperatures with increasing pressure and with increasing dioxane content, the latter effect being due to the much higher critical temperature of dioxane compared to carbon dioxide and ethane. The data presented can be used for optimizing SFC separations with mixed mobile phases.
Published Version
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