Influence of different deactivation methods on the sorption properties of diatomaceous supports for GLC

Summary Different types of diatomaceous supports, (pink and white) were deactivated in different ways: HCl gas treatment at high temperature, silanization and polymer coating with Carbowax 20 M. The adsorption effects of those supports when not coated with stationary phase were tested with samples of different polarity. The Carbowax modification of supports gives a surface of very low activity, irrespective of whether the pink or the cleaner white diatomite type was the initial material. The polymer coating behaves like a thin-layer of stationary phase, of considerably less polarity than the original Carbowax, and gives rise to a partition-like retention. The silanized supports are of moderate activity, the white type being less active than the pink one. This is explained by the higher content of aprotonic active sites in the latter, which cannot be blocked by silanization.