Direct analysis in real-time (DART) time-of-flight mass spectrometry (TOFMS) of wood reveals distinct chemical signatures of two species of Afzelia

Abstract

Key message Distinct chemical fingerprints of the wood of Afzelia pachyloba and A. bipindensis demonstrated an effective method for identifying these two commercially important species. Direct analysis in real-time (DART) timeof-flight mass spectrometry (TOFMS) allowed high-throughput examination of chemotypes with vast potential in taxonomic, ecological, and forensic research of wood.• Context Afzelia is a genus of valuable tropical timber trees. Accurate identification of wood is required for the prevention of illicit timber trade as well as for certification purposes in the forest and wood products industry. For many years, particular interest has been focused on attempts to distinguish the wood of A. bipindensis Harms from A. pachyloba Harms due to substantial differences in the commercial values of these two species.• Aims We investigated if wood chemical signatures and microscopy could identify the wood of A. bipindensis and A. pachyloba.• Methods We used two approaches, namely metabolome profiling by direct analysis in real-time (DART) time-of-flight mass spectrometry (TOFMS) and wood microstructure by light microscopy and SEM. In all, we analyzed samples from 89 trees of A. bipindensis, and A. pachyloba. • ResultsThe two species could not be separated by the IAWA standard microscopic wood features. SEM analysis showed considerable variation in the morphology of vestured pits; however, this variation was not species-specific. In contrast, DART-TOFMS followed by unsupervised statistics (Discriminant Analysis of Principal Components) showed distinct metabolome signatures of the two species.• Conclusion DART-TOFMS provides a rapid method for wood identification that can be easily applied to small heartwood samples. Time-and cost-effective classification of wood chemotypes by DART-TOFMS can have potential applications in various research questions in forestry, wood science, tree-ecophysiology, and forensics.

Improved wood species identification based on multi-view imagery of the three anatomical planes

“…Kitin et al. [ 42 ] used DART-TOFMS to study two species of Afzelia , Afzelia pachyloba and Afzelia bipindensis . Although the two species are not easily separated using the IAWA standard microscopic wood features, the results using DART-TOFMS reached an accuracy of 78%.…”

Improved Wood Species Identification Based On Multi-View Imagery of The Three Anatomical Planes

“…In Ravindran et al [20], 10 species of the Meliaceae family were identified based on deep convolutional neural networks, achieving an accuracy of 87% at species the level and an accuracy of 96% at the genus level. Kitin et al [26] used DART-TOFMS to study two species of Afzelia, Afzelia pachyloba and Afzelia bipindensis. Although the two species are not easily separated using the IAWA standard microscopic wood features, the results using DART-FORMS reached an accuracy of 78%.…”

Tracing the world’s timber: the status of scientific verification technologies for species and origin identification

“…Deklerck and Price et al (2021) showed that Baillonella toxisperma can be separated from other Sapotaceae species (Autranella congolensis, Tieghemella africana and T. heckelii) via DART TOFMS data and Discriminant Analysis of Principal Components (DAPC) (LOOCV = 96.61%). Kitin et al (2021) utilized DAPC to separate Afzelia bipindensis from A. pachyloba with a LOOCV accuracy of 78%; the low accuracy of the model was linked to the variability of mass spectra within each species group. Finally, Price et al (2021) separated seven species of Pterocarpus including P. erinaceus, P. soyauxii, P. santalinus, P. dalbergioides, P. indicus, P. macrocarpus and P. tinctorius using support vector machine (SVM) and DAPC; LOOCV accuracy of the models was 94% and 95%, respectively, and blind test accuracy was 100% for both models.…”

“…These studies have shown that wood analysis using DART TOFMS allows for rapid and reliable identification to genus or species level, and, once initial equipment costs are met, analysis is relatively straightforward and cheap (Dormontt et al 2015;Kitin et al 2021). DART TOFMS has been proven to be a clear contender as a means of supporting law enforcement agencies in the US, with leading Customs and Border Protection (CBP) to procure three of the instruments for testing different substances and materials including wood (Clark 2017).…”