Preparation and Characterization of Gold Nanoparticle-Modified Silica Monolith for Capillary Electrochromatography

A novel silica monolithic stationary phase functionalized with octadecanethiol gold nanoparticles was prepared for capillary electrochromatography (CEC). The bare monolithic silica column was prepared by a sol-gel process and has been chemically modified with 3-mercaptopropyl-trimethoxysilane, followed by immobilization of gold nanoparticles and modification by octadecanethiol. The relationship between plot of plate height and the linear velocity on gold nanoparticle-modified silica monolith was investigated, and a minimum plate height of about 7. 8 mu m for toluene was obtained. The electroosmotic flow characteristics of the gold nanoparticle-modified silica monolith and bare silica monolith (Silica) were studied by varying the percentage of organic modifier in buffer and buffer pH. To evaluate the column performance, hydrophobic alkylbenzenes as model compounds were tested on the prepared Silica, SH-modified (Silica-SH) and octadecanethiol modified (Silica-GNPs-C-18) monoliths. The electrochromatographic retention behavior of alkylbenzenes on Silica-GNPs-C-18 column was also investigated. The experiment results showed that Silica-GNPs-C-18 column exhibits typical reversed phase electrochromatographic behavior toward neutral solutes. Reversed phase CEC separations of four selected polar phenols were also demonstrated on Silica-GNPs-C-18 column using mobile phase containing 15% methanol.