“…In the FDA’s PAT definition , (“a system for designing, analyzing, and controlling manufacturing through timely measurements (i.e., during processing) of critical quality and performance attributes of raw and in-process materials and processes, with the goal of ensuring final product quality”), “analyzing” equates to the use of in situ analytical tools. A variety of analytical methods have been incorporated into the PAT toolbox for online process monitoring, including focused beam reflectance measurement (FBRM), − particle video microscopy (PVM), , infrared (IR) spectroscopy, ,− UV–vis spectroscopy, Raman spectroscopy, ,, nuclear magnetic resonance (NMR) spectroscopy, ,, and high-performance liquid chromatography (HPLC) . However, little information is provided on chemical structures by many of these measurements, which only give signals for characteristic functional groups, and this remains one of the barriers to the application of spectroscopy in PAT applications.…”