Mathematical Data Preprocessing

Samples that are measured using diffuse reflectance often exhibit significant differences in the spectra because of the nonhomogeneous distribution of the particles. Light scattering off the particles causes every spectrum, even of remeasurements of the same sample, to look a little bit different because of the particle size distribution and alignment with the incident beam of light. The correction method assumes that the wavelength dependency of the light scattering is different from that of the constituent absorption. The chapter presents the list of baseline correction methods. There are many ways of autocorrecting the spectrum baseline as a chemometric preprocessing step. Due to the multivariate nature of factor-based chemometric models, the direct relationship between the spectral response and the constituent concentration (univariate) is not very important. There are some mathematical enhancements that can be applied to data that are to be used in a multivariate model and would be useless for a univariate model.