Extraction of Chemical Information of Suspensions Using Radiative Transfer Theory to Remove Multiple Scattering Effects: Application to a Model Two-Component System

An approach for removing multiple light scattering effects using the radiative transfer theory (RTE) in order to improve the performance of multivariate calibration models is proposed. This approach is then applied to the problem of building calibration models for predicting the concentration of a scattering (particulate) component. Application of this approach to a simulated four component system showed that it will lead to calibration models which perform appreciably better than when empirically scatter corrected measurements of diffuse transmittance (T(d)) or reflectance (R(d)) are used. The validity of the method was also tested experimentally using a two-component (polystyrene-water) system. While the proposed method led to a model that performed better than the one built using R(d), its performance was worse compared to when T(d) measurements were used. Analysis indicates that this is because the model built using T(d) benefits from the strong secondary correlation between particle concentration and path length traveled by the photons which occurs due to the system containing only two components. On the other hand, the model arising from the proposed methodology uses essentially only the chemical (polystyrene) signal. Thus, this approach can be expected to work better in multicomponent systems where the path length correlation would not exist.