Lignin is the second most abundant natural biopolymer and potentially a valuable alternative energy source for conventional fossil fuels. In this study, Fourier-transform ion cyclotron resonance-mass spectrometry (FTICR-MS) in conjunction with phase correction was applied to study photooxidation products of lignin using a 7 Tesla (T) mass spectrometer. The application of 7 T FTICR-MS has often been inadequate for the analysis of complex natural organic matter because of insufficient resolving power as compared with high-field FTICR, which led to incorrect assignments of elemental formulae and discontinuous plots in graphical and statistical analyses. Here, the application of phase correction to the FTICR mass spectra of lignin oxidation products greatly improved the spectral quality, and thus, readily permitted characterization of photooxidation processes of lignin compounds under simulated solar radiation conditions.

No abstract

A non-targeted method for analyzing petroleum hydrocarbons in soil was established by extracting a wide range of PAC compounds using a model system. Here, sand was spiked with a heavy crude oil, which simulated a hydrocarbon contaminated soil of low soil organic matter (SOM). Soxhlet and supercritical fluid extraction (SFE) was optimized for PAXHs analysis in soil. A concept of using multidimensional ionization for ultrahigh resolution mass spectrometry was employed for detection using electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photo ionization (APPI) for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic heterocycles. Fourier transform mass spectrometry (FT-MS) with its ultrahigh mass resolution and high mass accuracy enables an unambiguous assignment of the detected ions obtained from different ionization methods, which provides a secure and comprehensive view of contaminants in soil on a molecular level. Over 95% of the spiked crude oil could be recovered by Soxhlet extraction using toluene, dichloromethane and acetone:n-hexane (1:1, v:v). In comparison, when using SFE with supercritical CO 2 the recovery was only about 50% but showed more polar compounds. Detailed analyses showed that besides 16 PAHs, a wide range with more than 10,000 PAXHs could also be successfully extracted.