IDENTIFICATION OF ARCHAEOLOGICAL AND RECENT WOOD TAR PITCHES USING GAS-CHROMATOGRAPHY MASS-SPECTROMETRY AND PATTERN-RECOGNITION

An analytical method has been developed (or the assignment of recent and archaeological wood tar pitches to the species of trees used for their preparation. It incorporates the prepurification by Kugelrohr distillation and solid-phase extraction followed by gas chromatography/mass spectrometry analysis. Distribution patterns of volatile, thermostable triterpenoids and steroids characterizing the biological origin of the pitches are evaluated by principal component analysis (PCA) and discriminant component analysis (DCA) of the data. Quantities of 10–100 mg of archaeological material can thus be characterized. Fourteen archaeological samples have been identified as birch bark pitches by comparison with recent pitches of known origin. In addition 28 substances present In recent barks and recent pitches could be identified showing that the method developed can also be applied to the chemotaxonomy of broad-leaved trees. © 1990, American Chemical Society. All rights reserved.