Distinction of three wood species by Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

Abstract

Dalbergia odorifera T. Chen, Pterocarpus santalinus L.F. and Pterocarpus soyauxii are three kinds of the most valuable wood species, which are hard to distinguish. In this paper, differentiation of D. odorifera, P. santalinus and P. soyauxii was carried out by using Fourier transform infrared spectroscopy (FT-IR), second derivative IR spectra and two-dimensional correlation infrared (2D-IR) spectroscopy. The three woods have their characteristic peaks in conventional IR spectra. For example, D. odorifera has obvious absorption peaks at 1640 and 1612 cm −1; P. santalinus has only one peak at 1614 cm −1; and P. soyauxii has one peak at 1619 cm −1 and one shoulder peak at 1597 cm −1. To enhance spectrum resolution and amplify the differences between the IR spectra of different woods, the second derivative technology was adopted to examine the three wood samples. More differences could be observed in the region of 800–1700 cm −1. Then, the thermal perturbation is applied to distinguish different wood samples in an easier way, because of the spectral resolution being enhanced by the 2D correlation spectroscopy. In the region of 1300–1800 cm −1, D. odorifera has five auto-peaks at 1518, 1575, 1594, 1620 and 1667 cm −1; P. santalinus has four auto-peaks at 1469, 1518, 1627 and 1639 cm −1 and P. soyauxii has only two auto-peaks at 1627 and 1639 cm −1. It is proved that the 2D correlation IR spectroscopy can be a new method to distinguish D. odorifera, P. santalinus and P. soyauxii.