Demystifying the tropics: FTIR characterization of pantropical woods and their α-cellulose extracts for past atmospheric ¹⁴C reconstructions

To ensure unbiased tree-ring radiocarbon (¹⁴C) results, traditional pretreatments carefully isolate wood cellulose from extractives using organic solvents, among other chemicals. The addition of solvents is laborious, time-consuming, and can increase the risk of carbon contamination. Tropical woods show a high diversity in wood-anatomical and extractive composition, but the necessity of organic-solvent extraction for the ¹⁴C dating of these diverse woods remains untested. We applied a chemical treatment that excludes the solvent step on the wood of 8 tropical tree species sampled in South-America and Africa, with different wood-anatomical and extractive properties. We analyzed the success of the extractive removal along with several steps of the α-cellulose extraction procedure using Fourier Transform Infrared (FTIR) spectroscopy and further confirmed the quality of ¹⁴C measurements after extraction. The α-cellulose extracts obtained here showed FTIR-spectra free of signals from various extractives and the ¹⁴C results on these samples showed reliable results. The chemical method evaluated reduces the technical complexity required to prepare α-cellulose samples for ¹⁴C dating, and therefore can bolster global atmospheric ¹⁴C applications, especially in the tropics.