Analysis of Asphaltenes and Asphaltene Model Compounds by Laser-Induced Acoustic Desorption/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Laser-induced acoustic desorption (LIAD)/electron ionization (EI) was used to Study asphaltene model compounds and asphaltenes derived from North American crude oil in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer (MS). Successful desorption by LIAD of all model compounds (including a polyphenylated vanadoyl porphyrin) as intact neutral molecules into the mass spectrometer indicates that this method allows the evaporation of most if not all components of asphaltenes into mass spectrometers for further characterization. Electron ionization is a universal ionization method that ionizes all organic compounds. Hence, it is not Surprising (hat all the model compounds studied were successfully ionized by using this method. Furthermore, this method yielded stable molecular ions for all model compounds studied. Because LIAD/EIMS provides MW information for these model compounds, this is almost certainly also true for all components of asphaltenes. Examination of asphaltene samples derived from North American crude oil by using this technique yielded a MW distribution of about 350-1050 Da and provided structural information for asphaltene components.