Rapid identification of bast fibers in ancient handmade papers based on improved characterization of lignin monomers by Py-GCxGC/MS

Abstract

The precise identification of hemp (Cannabis sativa L.) fiber in ancient papers is of great significance in the study of paper history. However, different species of phloem fibers belonging to bast fibers (e.g., hemp, ramie, flax, jute) used in traditional hand papermaking in the East Asian region present similar microscopic morphological traits, which renders their accurate identification problematic and may cause controversy in archaeological interpretations. In this study, a method for the precise identification of Cannabis fiber in ancient handmade papers by Py-GCxGC/MS was developed for rapid fiber characterization in ancient papers. The proposed approach was based on the separation of characteristic lignin monomers from lignocellulose by Py-GCxGC/MS, with an example of joss paper samples excavated from the archaeological site of Astana tombs dating to the Tang Dynasty. The bidimensional chromatographic separation of the pyrolysis signature of plant materials allows a well-structured layout in the 2D chromatograms. Therefore, it becomes possible to distinguish these different plant materials by applying a multivariate analysis treatment to the lignin monomers. The improved GCxGC separation of lignin monomers showed the benefit of the GCxGC profile for lignin monomer group identification as well as for the application of statistical analysis. The developed method presents the advantages of being rapid and effective for archaeological and cultural heritage applications in necessitating a tiny quantity of sample.