“…These variations result in dissimilar packing densities, intensity differences, light scattering effects, path length variations, and ultimately baseline shifts in the spectra (20). Instrumental effects such as random noise, changes in lamp intensity, and detector response may also cause variations within spectral groups and can adversely affect the robustness and reliability of the multivariate calibration model to be developed (5,20). In an attempt to eliminate, reduce, or standardize the effects of these variations on our multivariate model, we applied three different preprocessing methods, namely multiplicative scatter correction, standard normal variate, and Savitzky-Golay second derivative transformation with third-order polynomial using 7 filter points, to study the influence each pretreatment method on the robustness of our regression model.…”