Characterization of Asphaltenes Precipitated at Different Solvent Power Conditions Using Atmospheric Pressure Photoionization (APPI) and Laser Desorption Ionization (LDI) Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)

Abstract

In the present work, asphaltenes obtained using different n-heptane/crude oil ratios (HCORs) were analyzed using atmospheric pressure photoionization (APPI) and laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The main objective was to improve the understanding of the components of the crude oil that precipitate under different solvent power conditions. Analysis of the compositional distribution of the asphaltenes reveals that the decrease in solvent power produces an increase in double bond equivalent (DBE) and the number of heteroatoms per molecule, while the carbon number remains almost unaltered. This finding seems to indicate that one of the main drivers for precipitation is aromaticity as HCOR increases and, consequently, the solvent power decreases. Both APPI and LDI FT-ICR MS produce average values that describe the general tendencies obtained using other techniques. Additionally, APPI FT-ICR MS closely matches bulk data of the m...