Multi‐Analytical Characterization and Taxonomic Distinction of Australian Plant Exudates

Plant exudates have been used worldwide for millennia in broad applications due to their unique physicochemical properties. Indigenous Australians have used exudates in long-standing cultural and technical practices, including hafting adhesives and paint binders. Chemical characterization and botanical identification can provide important insight into the origin, properties, and usage of exudate materials from the archaeological past to the present. However, Australian exudates and cultural heritage materials have been far less examined compared to European, Asian, and North African counterparts. Here, we report combined Fourier transform infrared (FTIR) spectroscopy, X-ray Raman scattering (XRS) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and pyrolysis gas chromatography mass spectrometry (py-GC-MS) analyses for atomic- to molecular-level characterization of over 20 genera of Australian exudates. This research contributes to fundamental understanding of the chemistry of exudates that drives their usage as natural binders. Integration of all four techniques and multivariate statistics reveals chemical differences at both the genus and species level. We establish correlations between taxonomic groupings and chemical composition to identify key features for distinction of exudates. Our multi-analytical approach provides new insight into the unique chemistry of less well-studied Australian exudates, with impact on the characterization of exudates in important cultural and archaeological materials worldwide.