Characterization and selection of stationary phase for Gas -Liquid chromatography
By S. B. Puranik, P. N. Sanjay Pai and A.S. Mohammad
The function of the stationary liquid phase is to separate the sample components into discrete peaks. In addition, the liquid phase should have reasonable chemical and thermal stability. In order to function efficiently the stationary phase must remain in the liquid condition. Usually the lower temperature limit operations are kept 10-15 0 C below the upper temperature limit. The amount of column bleed (vaporization of the stationary liquid phase) must be minimized to prolong the column life, to prevent any fouling of the detector, and to maintain baseline stability on the chromatogram. It makes possible the separation of solutes with very similar properties: On the basis of their behavior with a solute, conclusions may be drawn concerning the nature and the general characterization of the particular solute; they contribute useful data to the knowledge of molecular interactions. Currently, no adequate directions are available for selection of columns. However selection has been proposed through matching of polarities of solutes with stationary phases. Certain theories based on Kovats retention indices and McReynolds Theory could be considered for this purpose. Improved resolution between the peaks was the primary objective for the new column selection, which was carried out based on the different models viz., Kovats retention indices and McReynolds Theory.
Key words: Kovats retention indices, polarity, stationary phase, McReynolds constants, Gas chromatography.
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