Characterisation of black carbon materials by pyrolysis–gas chromatography–mass spectrometry

Pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) was used to investigate the chemical structures of eight black carbon (BC) materials: hexane soot, gasoline soot, diesel soot, coal soot, grass soot, wood soot, grass charcoal and wood charcoal. Py–GC–MS data revealed that the pyrolytic products of the eight BC samples were all dominated in aromatic compounds, followed by smaller amounts of aliphatic compounds. O-containing pyrolytic products were also present in all eight BC samples. The data suggest that the structures of eight BCs were composed of highly aromatic structures that were cross-linked by aliphatic chain-like bridges and/or O-containing polar functional groups. Owing to the different fuel precursors and combustion conditions, the eight BC materials also differed in many respects. The pyrolytic products from soot BCs contained higher amounts of N-containing compounds, reflecting the combustion conditions. S-containing compounds were only present in pyrolytic products from three fossil-fuel soots, and can be used as a marker for soot from fossil fuels. Charcoal BCs can retain some plant structure, containing significant amounts of typical lignin-derived phenolic compounds. The results may be useful for interpretation of Py–GC–MS data for complicated BCs isolated from soils, sediments and aerosols.