| pubmed-article:18571186 | pubmed:abstractText | A thermal extraction-two-dimensional gas chromatography-mass spectrometry (TE-GC-GC-MS) method with heart-cutting is developed for quantitatively assessing nitrogen (N)-bearing organic species (e.g., pyrrole, pyridine, nitriles, and amines) in aerosols emitted from agricultural fires. Pyrolysis of the constituents in the crop residue is a likely formation pathway for these compounds. An evaluation of the TE-GC-GC-MS method proficiency for them confirms low carryover (<1%), adequate recovery (84-100%), high reproducibility (<9% RSD), picogram method detection limits, and a linear dynamic range spanning four orders of magnitude. The 14 substances for which quantitative results are available are primarily heterocyclic aromatic N compounds that comprise 0.7% (w/w) of the total fine aerosol mass. The benefits of TE-GC-GC-MS versus conventional GC-MS methods for organic N species in aerosols may depend on the matrix and the target N analyte concentration in that matrix; for the biomass burning aerosol examined in this study, the former approach reduces the unresolved complex mixture and detects organic N species not seen with GC-MS. We show another advantage of TE-GC-GC-MS is that it adequately resolves the anhydro-sugar (e.g., levoglucosan), alkanoic acid, and substituted phenol molecules in the biomass burning aerosol without the use of methylation or trimethyl-silyl derivatizing agents. | lld:pubmed |
