The in situ analytical pyrolysis of two different organic components of a synthetic environmental matrix doped with [4,9-13C] pyrene

Laser micropyrolysis GC–MS was used for in situ analysis of the coal and lignin components of a synthetic mixture. Designed to mimic environmental matrices such as soils and sediments, the mix comprised several possible soil precursors and was also amended with [4,9-13C]pyrene as part of concurrent research on the interaction of PAH pollutants and sedimentary organic matter. The labeled spike was consistently detected as the major pyrolysate in the in situ analyses of both lignin and coal components of the synthetic mix, indicating its effective sorption by these moieties of the mix. The remaining hydrocarbon distribution detected from the lignin was dominated by guiaicyl (i.e. methoxyphenol) compounds, whereas high abundances of aromatic (e.g. benzene, naphthalene, phenol and alkyl derivatives thereof) and aliphatic (e.g. n-alkene/alkane, prist-1-ene, hopanes) products were detected in the coal. Apart from the high concentrations of the 13C-spike, these data were very similar to molecular data obtained from the respective pyroprobe pyrolysis GC–MS analysis of pure lignin and coal samples. The untainted (i.e. apart from the 13C-spike) molecular signatures detected from the in situ analysis of the coal and lignin constituents indicates minimal organic contamination from the other constituents of the synthetic mix, successfully demonstrating the capability of the laser micropyrolysis GC–MS technique to selectively analyse the discrete organic entities within complex and heterogeneous mixtures.