Prediction of Boron Content in Wood Pellet Products by Near-Infrared Spectroscopy

A rapid method assessed the potential of near-infrared spectroscopy (NIRS) to estimate boron content of wood pellet products. Based on a comparison of NIR spectra data in the 1,100- to 2,200-nm wavelength region of Eastern black spruce (Picea mariana var. mariana) wood pellets treated with preservative concentrations ranging from 0 to 2 percent and from 0 to 20 percent glycol borate based disodium octaborate tetrahydrate (DOT), the minimum level of boric acid equivalent required to protect wood from biodegradation was revealed. Borate was indicated in the 1,700- to 1,900-nm wavelength region and the visible-NIR absorbance trended to a proportion higher for the lower borate concentrations and lower for the higher borate concentrations. These were correlated by projection to the latent structures partial least-squares regression method and the sample-specific standard error of prediction method. Calibration sets achieved R-2 values from 0.7 to 0.95, root mean square error (RMSE) ranging from 0.3 to 1.61 percent, and relative percent difference (RPD) ranging from 1.8 to 4.4, whereas validation statistics achieved R-2 values from 0.64 to 0.94, RMSE ranging from 0.33 to 1.65 percent, and RPD ranging from 1.7 to 4.3. These preliminary results indicate that NIRS should be able to provide a greater quantitative and qualitative technique of predicting boron content in wood products for the preservation industry.