Rapid Determination of the Chemical Composition and Density of Pinus radiata by PLS Modelling of Transmission and Diffuse Reflectance FTIR Spectra

Abstract

Summary Transmission and diffuse reflectance FTIR spectra of samples of Pinus radiata wood have been used as the basis of PLS-1 (partial least squares) and PLS-2 (projection to latent structures) models for the prediction of extractives, lignin, total carbohydrate and basic density. Very little difference was observed between models based on transmission spectra and those based on diffuse reflectance spectra. Because of the ease of sample preparation and presentation the diffuse reflectance technique was chosen as the method of preference. Similarly very little difference was observed between models prepared using PLS-1 and models prepared using PLS-2 correlations of diffuse reflectance spectra. Multiple correlation coefficients between the four measured properties and the diffuse reflectance spectra using PLS-2 modelling with four principal components are respectively: extractives, 0.87; Klason lignin, 0.84; total carbohydrate, 0.58; and density, 0.87.