Chromatographic Properties of Monolithic Silica Capillary Columns for Polar and Nonpolar Compounds in Reversed-Phase HPLC

摘要

Retention properties of monolithic silica C18 columns were examined for polar and nonpolar compounds. Monolithic silica columns were prepared from two kinds of starting materials, tetramethoxysilane (abbreviated as TMOS) or a mixture of TMOS and methyltrimethoxysilane (abbreviated as Hybrid), and modified with dimethyloctadecylchlorosilane (C18). Retention factors of various compounds on Hybrid-C18 are about twice as much as that on TMOS-C18. The two types of columns showed very similar retention selectivity with few exceptions. TMOS-C18 showed slight preference toward planar polynuclear aromatic hydrocarbons (PAHs) compared to bulky aromatic hydrocarbons, while Hybrid-C18 showed opposite tendency. Some TMOS-C18 columns showed peak tailing for PAHs, and also for basic compounds in an acidic mobile phase, while Hybrid-C18 and majority of TMOS-C18 columns resulted in good peak shape for these compounds.