Layer-by-layer self-assembled graphene oxide/silica microsphere composites as stationary phase for high performance liquid chromatography

Graphene oxide (GO) has been layer-by-layer assembled onto silica microspheres to form a GO/SiO₂ composite stationary phase. All the characterizations of GO/SiO₂ by elemental analysis, Raman spectroscopy and Fourier transformed infrared spectrometry confirmed that with the increase of the assembled layer, GO gradually increases on the silica surface. The chromatographic properties of bare SiO₂ and GO/SiO ₂ with different GO assembled layers show that the amount of GO plays an important role in the separation of analytes. Only the appropriate amount of GO on SiO₂ can perform a good chromatographic separation. The comparison between chromatographic performances of bare SiO₂ column, GO/SiO₂-2 column and C18 commercial column clearly show that GO/SiO₂-2 and C18 columns obtained a better separation; GO/SiO ₂-2 exhibits a large π-electron system and C18 exhibits hydrophobicity. The eluting order, peak width and resolution of analyte on GO/SiO₂-2 column was highly dependent on the size of its π-electron system, while on the C18 column the decisive factor is its hydrophobic property.