The application of near infrared (NIR) spectroscopy to inorganic preservative-treated wood

There is a growing need to find a rapid, inexpensive, and reliable method to distinguish between treated and untreated waste wood. This paper evaluates the ability of near infrared (NIR) spectroscopy with multivariate analysis (MVA) to distinguish preservative types and retentions. It is demonstrated that principal component analysis (PCA) can differentiate lumber treated with CCA, ACZA, or ACQ preservatives. Furthermore, separation according to wood species and assay zone was also observed. Within the range of preservative concentrations available, partial least squares (PLS) regression was also performed on the NIR data, from which retention levels were predicted. The results highlight the potential for this technique to predict the concentration, as well as identify the type, of inorganic preservatives present.