Nontarget Analysis of WPPO by GCxGC-HRTOFMS

Waste plastic pyrolysis oils (WPPO) are of growing interest as a source of more environmentally friendly alternative feedstock for producing chemicals and fuels. However, as WPPO are often produced from diverse sources with varying degrees of purity and cleanliness, more comprehensive analysis becomes necessary as compounds that are not typically found in traditional petrochemical sources can be present in these oils. Targeted screening is not enough to fully safeguard processes from potentially undesirable contaminants, which can reduce efficiency of reactions and foul production lines. To fully understand the chemical composition of such complex mixtures, nontargeted analysis is essential. This presentation focuses on analysis of WPPO using an unparalleled nontarget discovery tool: comprehensive two-dimensional gas-chromatography coupled to high-resolution time-of-flight mass spectrometry (GCxGC-HRTOFMS) capable of multi-mode ionization with electron ionization (EI), positive chemical ionization (PCI), and electron-capture negative chemical ionization (ECNI). This multidimensional analysis provides not only the enhanced chromatographic resolution of GCxGC, which separates individual oil components chromatographically in an easy-to-comprehend layout of fairways of similar chemical structures, but also the powerful analyte identification abilities of complementary ionization modes that can provide both detailed structural information and the high mass-accuracy molecular formulae for individual species.