MEMS-based column coated with reduced graphene oxide as stationary phase for gas chromatography

Abstract

This work presents the investigation of reduced graphene oxide (RGO) as a new type of stationary phase for gas chromatographic separation on a microcolumn which is fabricated on a silicon wafer by the application of microelectromechanical system (MEMS) techniques. A ZnO film synthesized by a sol-gel method is utilized as a supporting material between RGO and the column wall for inwall roughening to form a stable RGO stationary phase and increase gas-stationary phase interaction. The RGO/ZnO grafted on the column wall was characterized by SEM and FT-IR spectra. The experimental results demonstrate that good separations for mixtures of a wide range of organic compounds including alkanes and esters are achieved by the microcolumn coated with bilayer film. And the maximum column efficiency of 11:363 theoretical plates per meter for n-dodecane is obtained, which is higher than any previously reported values for chromatography columns coated with graphene and their analogs to the best of our knowledge. However, the RGO stationary phase shows obvious peak tailings for polar alcohols, which mainly originate from its specific π-π stacking interaction as well as the hydrophobic effect between analytes and the π-electron on the high surface area of reduced graphene oxide. This work greatly favors RGO coated chip columns for gas chromatographic separation in achieving micro-total analytical systems.