Inference of origin of Pterocarpus timber by chemical profiling of ambient ionization mass spectra

Abstract

In Pterocarpus, three out of 46 tree species (P. erinaceus, P. santalinus, and P. tinctorius) are listed as endangered and protected under Appendix II of CITES, and the status of several Pterocarpus species suggests that more will find a place on CITES in the future. As unsustainable forest exploitation has increased, regulations for timber traceability have also increased with the creation of such laws as the 2005 Lacey Act in the United States (Lacey Act, 2005) and the European Union Timber Regulation (EUTR) in 2013. These laws were implemented to ensure that members of the timber trade operated in accordance with guidelines and practiced due diligence, with the goal of halting illegal timber imports (FAO, 2016). Unfortunately, the illegal timber trade remains prevalent and has progressed into the third largest transnational crime (Mavrellis, 2017). To combat the prevalence of illegal timber, researchers have utilized Direct Analysis in Real Time Time-of-Flight Mass Spectrometry (DART-TOFMS). With the success found using DART-TOFMS for species identification, we investigated whether the method could be used to identify the original geographic region of timber through analysis of 211 samples taken from 12 Pterocarpus species taken from the Neotropics, Africa, South Asia, and Southeast Asia. We found that analysis using DART-TOFMS could identify the broad geographical provenances of the timber with an accuracy of 98%. This research demonstrated that DART-TOFMS can be used to detect the phytochemical trends that exist between timber species occupying broad geographic regions.