Charles H. Phoebe

Dependence of reversed-phase retention of ionizable analytes on pH, concentration of organic solvent and silanol activity

In reversed-phase chromatography, the retention of ionizable analytes is influenced by the ionic properties of the packing caused by surface silanol groups. We have measured the ion-exchange properties of both reversed-phase bonded phases and their underlying base materials. The probe used in this part of the study was bretylium tosylate. The acquired knowledge is then used for a complete and quantitative understanding of the retention behavior of ionizable compounds as a function of the pH of the mobile phase and the solvent composition. We have studied the retention pattern of a broad range of acids, bases, and polyfunctional analytes over the pH range from 2 to 11 and from water to 80% acetonitrile. A few application examples demonstrate the relevant findings.

High-Performance Liquid Chromatography of Derivatized and Non-Derivatized Oligosaccharides: A Review

Abroad range of high-performance liquid chromatography (HPLC) techniques are available for the separation of oligosaccharides, which can be categorized in several different ways. We have chosen to divide the subject into two sections. The first section covers separation techniques, while the second addresses detection techniques.