Characterization of tobacco lignin preparations by Curie-point pyrolysis-mass spectrometry and Curie-point pyrolysis-high-resolution gas chromatography/mass spectrometry

Two extraction procedures to obtain a lignin fraction from tobacco were compared with Curie-point pyrolysis-mass spectrometry and Curie-point pyrolysis-gas chromatography/mass spectrometry. Both fractionation methods resulted in a lignin-enriched residue on which residual non-lignin polymers were attached. The Klason lignin procedure, which involves treatment with 72% sulphuric acid, revealed deficiencies towards the removal of alkaloids, carbohydrates, proteins, and lipids. As a consequence, the weight data on several chemical compound classes, i.e. the protein and lignin content of the Klason lignin residues, are estimated incorrectly. The Willstatter procedure, which involves treatment with hydrochloric acid, resulted in a selective removal of nitrogen-containing compounds, but affected the carbohydrate moiety only partially. The two extraction procedures investigated are not suitable to obtain a pure lignin fraction from tobacco. However, both purification methods resulted in a comparable relative distribution of lignin pyrolysis products in the lamina material of the flue-cured and burley type tobacco. The difference in distribution of lignin markers in both ‘lignin’ preparations of lamina and midrib material of the flue-cured type tobacco suggests a difference in chemical composition in the plant.