Wetting transition in alkane liquids on silanised diatomaceous gas chromatographic supports

For systems of an alkane stationary phase on widely used silanised diatomaceous supports, plots of retention volume of a polar solute against liquid loading show a pronounced peak. The phenomenon has been explored by systematically varying the support, stationary phase and solute. The critical loading at the steep left-hand side of the peak is independent of the polar solute used but depends on the stationary phase and support. The slope of the right-hand side of the peak is characteristic of the support, viz. Chromosorb P and Chromosorb G. Chromosorb W exhibits no peak. A previous proposal that a form of wetting transition in the liquid distribution on the support is involved has been confirmed. The results are interpreted in terms of a new version of the wetting transition model which takes into account the pore structure of the diatomaceous support as well as the surface tensions of the stationary liquid and support. The wetting transition appears to occur as liquid first spreads into pores of a size which provides the bulk of the porosity of each support. Copyright (C) 1998 Elsevier Science B.V.