Transition metal oxide nanoparticles as surfaces for surface-assisted laser desorption/ionization mass spectrometry of asphaltenes.

We report the first use of NiO, FeO, TiO, and CoO nanoparticles as surfaces for surface-assisted laser desorption/ionization (SALDI) mass spectrometry of asphaltenes. Higher ratios (S/Ns) for asphaltene species were observed using NiO and FeO nanoparticles for SALDI as compared to LDI, where both surfaces consistently provided 2- to 3-fold improved S/Ns. The new SALDI detection method showed reliable adsorption data measuring supernatant solutions after 24 hour asphaltene adsorption on NiO, FeO, and CoO. These results indicated that NiO has a higher adsorption affinity than FeO and CoO for asphaltene molecules, corroborating reported asphaltene adsorption on metal oxide nanoparticles.