Gas-liquid-solid chromatography-theoretical aspects and analysis of polar compounds

Adsorptive modifications on graphitized carbon blacks, (graphitized Sterling FT and Graphon) carried out by deposition of polymeric macromolecules of polyethylene glycol 1500 (PEG 1500) have been evaluated by increasing the surface concentration of PEG 1500 up to the formation of a few layers on the adsorbing media. The role played by both the liquid and the solid medium in the sorption process of vapors has been investigated by measuring heats, entropies, and capacity ratios for some polar and nonpolar eluates at various liquid/solid ratios. Experimental evidence is given for the occurrence of multilayer adsorption of macromolecules of PEG 1500 on the graphitized carbon surface. A simple, chromatographic criterion is suggested to evaluate the completion of the first layer of the liquid phase. The great usefulness of liquid-coated solids in the chromatographic analysis has been made evident by evaluating gas-liquid-solid columns in terms of selectivity, efficiency, and thermal stability. Also, the high performance of such columns has been exploited in the elution of some interesting, very dilute aqueous solutions of polar compounds.