RETENTION STUDY ON SILICA-GEL IN HIGH-TEMPERATURE LIQUID-CHROMATOGRAPHY (HTLC)

Retention volumes (V-N) of different kinds of test compound have been measured on silica gel as a function of column temperature (T) in the range 20 to 210 degrees C, n-Heptane and mixtures of n-heptane and pol ar modifiers were used as mobile phases. With nC7 and nC7-1,4-dioxane mixtures, there was a good linear relationship between In VN and 1/T f or column temperatures above 100 degrees C. When more polar modifiers such as butanol, ethanol and acetic acid were used, 'N'-shaped curves were obtained for the plots of ln V-N against 1/T. Possible explanatio ns of this retention behavior have been proposed on the basis of relat ed studies and common physical chemistry relationships. Column equilib ration time after alteration of water content or column temperature is greatly reduced at elevated temperatures. This will benefit the appli cation of LSC on silica gel.