Petroleomics by ion mobility mass spectrometry: resolution and characterization of contaminants and additives in crude oils and petrofuels

Abstract

Ion mobility-mass spectrometry (IM-MS), performed with exceptional resolution and sensitivity in a new uniform-field drift tube ion mobility quadrupole time-of-flight (IM-QTOF) instrument, is shown to provide a useful tool for resolving and characterizing crude oils and their contaminants, as well as petrofuels and their additives. Whereas direct analysis of a crude oil sample contaminated with demulsifiers by the classical ESI(±)-FTICR-MS petroleomic approach was unsatisfactory since it responds only with abundance and m/z, and ionization is impaired due to suppression of polar compounds of crude oil by additives likely used in petroleum industry, IM-MS enables mobility separation of ions, particularly of double bond equivalent (DBE) series for a giving C_nX class providing separated spectra which are typical obtained either for the crude oil or the contaminants, even suffering of ion suppression or low ionization efficiency. The combination of improved IM resolution and high mass resolving power (40,000@400) of the QTOF instrument provides useful information on class (N, NO, NS, etc.), carbon number (C_n), and unsaturation (DBE) levels for crude oils, allowing one to infer geochemical properties from DBE trends that can be compared with IM-MS data. As demonstrated by results of gasoline samples with additives, the IM-MS system also allows efficient separation and characterization of additives and contaminants in petrofuels.