Preparation and characterization of open-tubular capillary column modified with graphene oxide nanosheets for the separation of small organic molecules.

A novel coated capillary was prepared by immobilizing graphene oxide (GO) on the fused-silica capillary (75 μm i.d.) which was derivatized by 3-aminopropyl-trimethoxysilane (APTMS). The bare capillary, APTMS modified capillary (NH2-capillary) and GO coated capillary (GO-capillary) were characterized by streaming potentials (SPs), fluorescence microscope and scanning electron microscope (SEM). The results indicated that the capillary was successfully modified with GO sheets via covalent bonding and electrostatic effect. Compared with bare capillary, greater separation efficiency was achieved by GO-capillary column as a result of the increasing interactions between the small organic molecules and the inner wall of the GO-capillary column originated from the π-π electrostatic stacking. For three consecutive runs, the intra-day relative standard deviations (RSDs) of migration time and peak areas were 0.6-4.3% and 2.8-9.3%, respectively. The inter-day relative standard deviations of migration time and peak areas were 0.2-8.3% and 4.5-9.6%. Additionally, one GO-capillary column could be used for more than 100 runs with no observable changes on the separation efficiency.