Effect of polymer loading on the electrical and thermodynamic properties in relation to gas chromatographic applications

Different layers, 5, 10, 15, and 25% (w/W), of the three studied polyethyle ne glycols (PEGS) having different molecular weights, 600, 4000, and 20,000 , were used for coating on chromosorb pink acid washed (P AW). The polarity and selectivity of the prepared packing columns and their thermodynamic pa rameters were determined via inverse gas chromatography. The effect of poly mer-layer thickness on the polarity was studied dielectrically. The depende nce of specific retention volume, enthalpy, and entropy upon the loading of polymer on support were also studied. In all investigated polymers, the lo ads 5 and 10% deactivate the support surface, resulting in a decrease in it s capacitances, which reflects the polarity. The loads 15% PEG20,000 and 25 % PEG4000 can elute n-alcohols and exhibit high efficiency of separation; h owever, in the case of PEG600, loading has to exceed 25% to be sufficient f or eluting n-alcohols. The lower thickness of the coated polymers was prefe rred for good separation of saturated hydrocarbons and also for cyclohexane and aromatic hydrocarbons. (C) 2001 John Wiley & Sons, Inc.