Mass spectrometric characterization of water soluble organics in heavy oil retort

Abstract

A unified scheme is developed to demonstrate the necessity of a synergistic approach using several mass spectrometry methods for characterization and identification of water soluble organics in heavy oil retort. Elements of the scheme include a method for gas chromatography-mass spectrometry (GC-MS), high resolution mass spectrometry (HRMS) and mass spectrometry-mass spectrometry (MS-MS) with electron impact and fast atom bombardment ionization and a computerized library search. GC-MS, HRMS and MS-MS are well-established as powerful and versatile tools for identifying components of organic mixtures. Many improvements have been incorporated in order to provide the maximum amount of information that can be derived from the mass spectrometry methodologies. Each element of the analytical scheme is applied to complex samples of aqueous organic materials extracted from heavy oil retorts. The project focuses on development of methods rather than acquisition of compositional data; therefore, emphasis is placed on data which most clearly illustrate the utility and limitations of a given method. Criteria is developed to evaluate the informational content of the mass spectrometric methods. The elements of the scheme provide different perspectives on components in a highly complex sample. Each methodology supplies specific data not obtainable from other methods. GC-MS serves as an excellent survey analysis, and when combined with selective ion monitoring and the library search program, isolates specific groups of compounds without extensive sample treatment. MS-MS and the library search program are used to extract structural information. HRMS is used to determine elemental composition of mass resolved ions. PBM assists in structure elucidation by providing state-of-the-art library retrieval capabilities. PBM compensates both for the presence of mixtures in an unknown and for the wide variety of experimental conditions under which the reference library compounds were run. The inherent analytical power of the individual methodologies is extensive; however, results indicate that the mass spectrometry methods are used most effectively in concert with each other.