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. Author manuscript; available in PMC: 2019 Jan 15.
Published in final edited form as: Int J Pharm. 2017 Nov 2;535(1-2):68–85. doi: 10.1016/j.ijpharm.2017.10.056

Table 4.

Promising PAT tools for prospects in Pharmaceutical HME

PAT Tool Principle Site & Type of Analysis Applications Advantages Limitations Ref
Terahertz Spectroscopy Electromagnetic wave, Terahertz radiation 0.1 THz to 10 THz Die & Inline Differentiate Crystal Forms, Intermolecular Bonding, Refractive Index Measurement, Insensitive to Thermal Interferences High Cost, Complex System (Strachan et al., 2004; Zeitler et al., 2006)
Ultrasonic Spectroscopy Hi frequency acoustical wave Die, Barrel & Inline or Online API Quantification, Residence Time Distribution, Particle Size Distribution, Crystal Size Distribution, Good Penetrability, Easy to change wavelength of ultrasonic wave Probe adapter required (Li et al., 2004; Shukla et al., 2010; Stelzer et al., 2013)
Dielectric Spectroscopy Electric Field and measures energy associated with dipole orientation. Die & Inline Melt Rheology and Quantification Useful to analyse physical/chemical structures of organic materials Limited depth penetration measures at surface (Gottwald and Scheler, 2005)
NMR Spectroscopy Magnetic field Next to Die & Online Monitor API and Polymer interaction, Different polymorphs Sensitive with small amounts of API High temperature decreases magnetic field (Gottwald and Scheler, 2005)
Rheometry Capillary, Rotational & Oscillatory Between screw and die & Inline/On line Measures Viscosity, and linear viscoelastic behaviour, Reaction kinetics, Melt strength Thermal degradation is also noted with reduction in viscosity High shear rates influence morphology of product (Covas et al., 2004; Rajan et al., 2010)