ABSTRACT
This chapter describes a rapid, on-line procedure for the regeneration of silica-based C8 and C18 reversed-phase columns and demonstrates the value of peptide standards for monitoring improvements in column performance. Rederivatization of the C18 packing with the octylsilane reagent produced a mixed C8/C18 bonded phase. Although chlorodimethyloctadecylsilane has been successfully used in the authors' laboratory to derivatize silica supports, there are more problems associated with its use than the corresponding octylsilane. The incorporation of a base such as pyridine in the silanization reaction mixture is advantageous in neutralizing hydrogen chloride that is released during reaction of the chlorodimethyloctylsilane with free silanols on the silica surface. Gradual dissolution of the silica matrix over a long period of use, however, will probably make further regeneration impractical at some point. Hydrolysis of the siloxane bond formed between silanols on the silica surface and the alkylsilane reagent occurs preferentially in highly aqueous mobile phases.
