Determination of the minimum allowable operating temperature of stationary phases in capillary columns by inverse gas chromatography.

A method was developed to determine the minimum allowable operating temperature (MiAOT) of wall coated open tubular capillary columns. Two polyethylene glycol and fourteen polysiloxanes phases with different side groups (methyl, phenyl, cyanopropyl, trifluoropropyl, n-octyl) and backbone stiffening units (tetramethyl-p-silphenylene, tetramethyl-p,p'-sildiphenylene ether, carborane) were investigated by inverse gas chromatography. A sigmoidal profile of temperature versus column efficiency was found for almost all phases, as the column efficiency increased with temperature. The MiAOT was defined as that temperature where the column efficiency is half of its original value at elevated temperatures. It was found that the MiAOT of a stationary phase is approx. 60 K higher than its glass transition temperature.