Importance of Using Complementary Process Analyzers for the Process Monitoring, Analysis, and Understanding of Freeze Drying T. R. M. De Beer M. Wiggenhorn R. Veillon C. Debacq Y. Mayeresse B. Moreau A. Burggraeve T. Quinten W. Friess G. Winter C. Vervaet J. P. Remon W. R. G. Baeyens 10.1021/ac9010414.s001 https://acs.figshare.com/articles/journal_contribution/Importance_of_Using_Complementary_Process_Analyzers_for_the_Process_Monitoring_Analysis_and_Understanding_of_Freeze_Drying/2827954 The aim of the present paper is to demonstrate the importance of using complementary process analyzers (PAT tools) for the process monitoring, analysis, and understanding of freeze drying. A mannitol solution was used as a model system. Raman spectroscopic, near-infrared (NIR) spectroscopic, plasma emission spectroscopic, and wireless temperature measurements (TEMPRIS) were simultaneously performed in-line and real-time during each freeze-drying experiment. The combination of these four process analyzers to monitor a freeze-drying process is unique. The Raman and NIR data were analyzed using principal component analysis (PCA) and multivariate curve resolution (MCR), while the plasma emission spectroscopic and wireless temperature measurement data were analyzed using univariate data analysis. It was shown that the considered process analyzers do not only complement but also mutually confirm each other with respect to process step end points, physical phenomena occurring during freeze drying (process understanding), and product characterization (solid state). Furthermore and most important, the combined use of the process analyzers helped to identify flaws in previous studies in which these process analyzers were studied individually. Process analyzers might wrongly indicate that some process steps are fulfilled. Finally, combining the studied process analyzers also showed that more information per process analyzer can be obtained than previously described. A combination of Raman and plasma emission spectroscopy seems favorable for the monitoring of nearly all critical freeze-drying process aspects. 2009-09-15 00:00:00 PAT plasma emission spectroscopic multivariate curve resolution NIR PCA Complementary Process Analyzers plasma emission spectroscopy univariate data analysis temperature measurement data Freeze DryingThe aim TEMPRIS process analyzers process step end points MCR