Chemotaxonomic application of Py-GC/MS: Identification of lacquer trees

The trees of the species Rhus vernicifera, Rhus succedanea and Melanorrhoea usitate grow in various regions of Asia and their sap is used, for thousands of years, as coating materials for the most varied kinds of objects. After drying, the sap of these trees forms a very hard and durable polymer, commonly known as oriental lacquer. The sap consists of water, polysaccharides, glycoproteins, enzymes and a mixture of derivatives of catechol whose composition differs with the species. In this work, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was applied successfully to the identification of these species through the analysis of their saps. The saps of the three species of lacquer trees were studied and the method developed was applied to identify a tree whose species was unknown. Results show that pyrolysis is an alternative and efficient technique to identify the species of lacquer trees.