Implementation of spatial filtering technique in monitoring roller compaction process.

This study investigates the use of the spatial filtering technique (SFT) to monitor the particle size distribution (PSD) of granules obtained by roller compaction. In the first part of the study, the influence of the selected process and formulation parameters on the PSD of granules is monitored at-line using SFT. The correlation between the PSD obtained by SFT, sieve analysis, laser diffraction, and dynamic image analysis was satisfactory. The same trend was observed with all methods; however, SFT proved to be especially advantageous for monitoring the PSD of irregularly shaped granules obtained by roller compaction. Another aim of this study was to investigate the suitability of using the SFT method as a potential process analytical technology (PAT) tool for monitoring and predicting the PSD of granules obtained by roller compaction. The SFT model for d10 was poor due to less precise detection of smaller particles by SFT; nevertheless, the models for d50 (R = 0.93) and d90 (R = 0.93) were very good. The at-line models were further tested in real time on samples collected during the milling of ribbons. The correlation between the predicted and achieved values was good; however, it was time and formulation dependent.