Direct Mass Spectrometry of tar sands: A new approach to bitumen identification

The activities related to the evaluation of the organic fraction of tar sands are acquiring more importance from economical and technical points of view due to the increased variety of sample composition and origin. Conventionally, the analyses of bitumen in tar sands are based on preliminary extraction from the inorganic matrix and further characterisation of physical and chemical features by means of different methods. A new approach to characterise the tar sand is now proposed, based on the direct insertion of tar sand into mass spectrometer chamber without any previous separation or treatment and further vaporisation under vacuum at increasing temperature and analysis of its components. DIP-MS (Direct Insertion Probe-Mass Spectrometry) allows separating the bitumen components from the solid inorganic matrix according to their boiling points up to masses of 700 m/z and directly analysing them in one only step, even if they are characterised by high boiling point, high steric hindrance or low solubility, that usually limit their evaluation by chromatographic methods. This new application of DIP-MS approach is here described on model materials and on a series of real tar sand samples coming from different geological areas. Differences are evidenced among the tar sands on the basis of the evolution of their mass spectra. The information so obtained was compared and confirmed with other analytical techniques that are commonly used for crude oil and bitumen characterisation. This approach is proposed for an on-field application for fast screening of real samples in the perspective to acquire information on the most relevant organic species in the bitumen for comparative purposes and rough evaluation of the potentiality of tar sand fields. (C) 2013 Elsevier Ltd. All rights reserved.