Combining NIR Transmission Spectroscopy, Time-Resolved Spectroscopy and Diffusion Theory for Analysis of Intact Pharmaceutical Tablets

In recent years Near Infrared (NIR) Spectroscopy has become a valuable technique for determining the amount of active substance in pharmaceutical tablets. This is due to its fast and non-destructive performance. Even though this method works well it suffers from a few drawbacks, which makes improvements of interest. Conventional NIR spectroscopy is unable to separate the scattering from the absorption, whereas this is possible with time-resolved spectroscopy. In this thesis, two different evaluation methods were used to extract the absorption coefficients from the scattering coefficients in the conventional NIR measurements by using time-resolved spectroscopy and diffusion theory. These methods eliminated the effects of scattering and reconstructed the true absorption. Chemometric evaluations showed that both evaluation methods investigated in this thesis were better than conventional NIR spectroscopy to predict the amount of active substance. Not only was the chemical content analyzed, but also other tablet features. It appeared as if the particles in the tablets were lumped together during manufacturing when the compression forc