Proton nuclear magnetic resonance (1H-NMR) before and after oxidation of asphaltene was analyzed using a Bruker Ascend 700 M nuclear magnetic resonance spectrometer with deuterated chloroform (CDCl3) as solvent.
Infrared spectra (IR) of pristine asphaltene, MeOHS, and MeOHI were analyzed by a Nicolet 6700 Fourier transform infrared spectrophotometer.
The chemical composition of MeOHS was analyzed with a Shimadzu gas chromatograph/mass spectrometer (GC/MS).