Cooperative adsorption effects in gas—liquid—solid chromatography

Abstract

The specific retention volumes of acetone, methanol, and benzene were determined at 60 and 90°C for 14 different liquid loads of squalane, coated on silanized Chromosorb P and on deuterated, silanized Chromosorb P. The specific retention volume of benzene was not influenced by the sample size, liquid load, or type of support. Conversely, the retention volume of acetone displayed two distinct maxima at intermediate liquid loads. In addition, significant isotope exchange was observed between methanol and the deuterated, silanized support at relatively high liquid loads (5–12%). The retention volume maxima were interpreted with a model involving cooperative adsorption on the solid support along with an “autophobic” liquid distribution model. Enhanced retention of acetone occurred at low loads because of cooperative adsorption effects caused by lateral interactions between the stationary liquid phase and acetone molecules, adsorbed on the uncoated support surface. At higher liquid loads, the retention of acetone decreased due to increased coverage of the surface by squalane. Both of these phenomena have been observed in many other adsorption systems with non-porous adsorbents.