SUPPRESSION OF THE EFFECT OF METAL IMPURITIES IN ALKYLSILYLATED SILICA PACKING MATERIALS

Octadecylsilylated silica packing materials prepared from octadecyltrichlorosilane showed much better performance than those prepared from octadecyldimethylchlorosilane for chelating compounds that can interact with metal impurities in the silica support. Stationary phases containing an ether linkage in the alkyl group also showed improved performance. The presence of polar groups and the increased hydrophilicity of such stationary phases can account for the results based on the better accessibility of metal sites in a hydrophobic stationary phase. Similar results were obtained with carboxylic acids and phenols. Packing materials prepared from high-purity silica gel showed good performance for all the solutes studied, regardless of the functionality of the silylating reagents.