Preparation of a polyglycol-C-8 bonded phase and its characteristics

A new bonded phase containing both non-polar C-8 and polar polyglycol chain s was synthesized in two steps. Silica was first silanized with octyltrimet hoxysilane and then the intermediate product was reacted with tetraethylene glycol to introduce the polar group. The bonded phase exhibits a selectivi ty different from that of C-8 or C-18 reversed phases with a mixed-mode ret ention mechanism. The silanol effect on the polyglycol-C-8 bonded phase was examined with the test mixture proposed by Engelhardt and co-workers. The experimental results indicate that the new bonded phase displays less silan ol effect. The observed tailing of some ionizable species resulted mainly f rom their partial dissociation at the pH values of eluents close to the pK( a) values of the solutes. Some potential applications of the bonded phase a re also given.