Publication Date:
2017-11-23
Description:
Many environmental samples, including water, soils, sediments and airborne particles and vapours contain complex mixtures of hydrocarbons, often deriving from crude oil either before or after fractionation into fuels, lubricants and feedstocks. Comprehensive 2D Gas Chromatography- Time-of-Flight Mass Spectrometry (GC × GC-ToFMS), offers a very powerful technique separating and identifying many compounds in complicated hydrocarbon mixtures. However, quantification and identification of individual constituents at high ionization energies would require hundreds of expensive (if available) standards for calibration. Although the chemical structure of hydrocarbons does matter for their environmental impact and fate, strong similarities can be expected for compounds having very similar chemical structure and carbon number. There is, therefore, a clear benefit in an analytical technique which is specific enough to separate different classes of compounds, and to distinguish homologous series, whilst avoiding the need to handle each isomer individually. Varying EI (electron impact) ionization mass spectrometry significantly enhances the identification of individual isomers and homologous compound groups, which we refer to as isomer sets. Advances are reported in mapping and quantifying isomer sets of hydrocarbons (≥ C12) in diesel fuel, lubricating oil and diesel exhaust emissions. Using this analysis we report mass closures of ca. 90 % and 75 % for diesel fuel and lubricating oil.
Electronic ISSN:
1867-8610
Topics:
Geosciences
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