GC/APLI-FTMS - a sensitive method to detect aromatic compounds in complex mixtures

摘要

A new method, GC/APLI-FTMS, for the detection of aromatic compounds in complex mixtures has been developed which combines GC as a high performance separation method, APLI as a very sensitive ionization method for aromatic compounds and FTMS which is known for accurate mass measurements. APLI is soft ionization method in contrast to common GC/MS systems with EI source. Therefore, this hyphenation method is well suited for the characterization of volatile aromatic compounds of complex mixtures like waste water or oil samples. The GC-APLI/D source has been combined with TOF mass spectrometers already, however, FTMS provides higher resolving power and mass accuracy compared to TOF detectors. Therefore, GC-APLI-FTMS is well suited for the analysis of very complex samples like oil. GC/APLI has been coupled to an FT-ICR instrument to detect polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in fuel oil and gas oil. Also, a river sediment standard was analyzed concerning specific PAHs. A GC system was coupled with a GC/APLI/D source to a solarix 12 T FT-ICR mass spectrometer. The elemental compositions of PAHs and PASHs in gas oil and fuel oil as well as in a river sediment standard have been analyzed by exact mass and retention time in positive ion mode. Samples with different amounts of sulfur have been tested. PAHs and PASHs could be identified just by retention time and accurate mass combined with the isotopic pattern of the molecular ion. Extracted ion chromatograms (EICs) with 1 mDa mass tolerance have been used to identify isomers of PAHs and PASHs. Species with a small mass difference with similar retention times can also be separated due to high resolving power of the FT-ICR MS technique.