Raman spectroscopic characterization of RP-18-type chemically bonded stationary phases for liquid chromatography

This study is the first Raman spectroscopic characterization of conventiona l chemically bonded liquid chromatographic (LC) stationary phases of the RP -18 type using the high-power Nd:WVO4 neodymium laser. Raman spectra were o btained for octadecyl (C-18) chemically bonded silica-based stationary phas es, as well as for silica, aminopropyl (NH2), cyanopropyl (CN), diol (OH), octyl (C-8), and methyl (C-1) phases for comparison. This study demonstrate s that Raman spectroscopy using the high-power neodymium laser can be used to study RP-18-type LC stationary phases and to quantitate the density of c overage of the silica matrix with octadecyl ligands, The paper presents the experimental setup and conditions used to obtain Raman spectra of commerci al RP-18-type chemically bonded stationary phases and examines the spectros copic similarities and differences observed for different bonded ligands ty pically used in reversed-phase and normal-phase LC separations.