Evolved gas analysis for petrochemical products using a newly developed TG–Fast-GC–SPI/EI–HRTOFMS system.

The online combination of thermogravimetry with mass spectrometry (TG-MS) is widely used for evolved gas analysis (EGA). In recent years, also hyphenated systems featuring an additional gas chromatographic (GC) separation to form a TG-GC-MS were available. A newly developed system, which is presented in this study, expands the possibilities of common TG-GC-MS by implementing new features.   A novel modulator system and a fast-GC were developed. In combined use, it allows a short separation within a 30 s-temperature-programmed GC run. Advantages are the enhanced signal intensities, due to accumulation of the evolved gases in the modulator and the possibility to differentiate between isobaric and isomeric compounds on the basis of different retention time. Furthermore, a time-of-flight (TOF) mass spectrometer with a maximum mass resolution of 5000 M/ΔM was applied. It ensures high acquisition rates and enables the distinction of isobaric compounds, which is not possible with low resolution mass spectrometers. Additionally, fast switching between hard electron ionization (EI) and soft single-photon ionization (SPI) is possible and allows quasi-simultaneous acquisition with both ionization techniques. This offers standard ionization energy mass spectra for library search in EI mode and mass spectra where the molecule ions are most abundant at the same time in SPI mode.   The new system was applied to characterize various petrochemical samples such as crude oils, oil shales, algae- and other bio-feedstock-based oils and fuels. The gained multi-dimensional data sets facilitate the determination of elemental compositions and give further insights into these highly complex matrices