Process spectroscopy,—characterization physical properties

In essence, the test battery should include XRPD to characterize crystallinity of excipients, moisture analysis to confirm crystallinity and hydration state of excipients, bulk density to ensure reproducibility in the blending process, and particle size distribution to ensure consistent mixing and compaction of powder blends. Often three-point PSD limits are needed for excipients. Also, morphic forms of excipients should be clearly specified and controlled as changes may impact powder flow and compactibility of blends. XRPD, DSC, SEM, and FTIR spectroscopy techniques may often be applied to characterize and control polymorphic and hydrate composition critical to the function of the excipients. Additionally, moisture sorption studies, Raman mapping, surface area analysis, particle size analysis, and KF analysis may show whether excipients possess the desired polymorphic state and whether significant amounts of amorphous components are present. Together, these studies will ensure lotto-lot consistency in the physical properties that assure flow, compaction, minimal segregation, and compunction ability of excipients used in low-dose formulations. 

High-Temperature Application. Vinyl Acetate Distribution in Copoly (ethylene-vinyl acetate). In the characterization of polymers, molecular distribution and composition are two critical parameters. Every physical property and processing change of the material can be related to these two parameters. With copolymers, IR spectroscopy can be used for determination of the distribution of one or both monomers within the molecular weight distribution. 

Dziki et al. (93) used near-infrared spectroscopy to characterize the mobility of water within the sarafloxacin crystal lattice differences in the location or orientation of the water molecules within the crystal were detected. The presence or absence of water in the crystal lattice can affect physical properties and processing ability. Analysis of near-infrared spectra of polymer samples allows us to distinguish between acceptable and unacceptable batches for formulation purposes. 

Various sophisticated instrumental methods have been developed to characterize polymer blends and compatibility, including thermal, microscopy, spectroscopy and other processing techniques. Recently, ultrasound has also been applied extensively to the study of polymer blend properties in both solutions and solids. The ultrasonic velocity and attenuation by the interaction of the propagating wave were used to investigate the various physical properties of the polymer blends, including density, compatibility, molecular orientation, and phase inversion. 

Analytically, IR (FTIR) spectroscopy is unquestionably one of the most versatile techniques available for the measurement of molecular species in the laboratory today, and also for applications beyond the laboratory. A major benefit of the technique is that it may be used to study materials in almost any form, and usually without any modification all three physical states are addressed solids, liquids and gases. Also, it is a fundamental molecular property, and as such the information content can be considered to be absolute in terms of information content, and as such can be very diagnostic in terms of material purity and composition. Traces of impurities can be both uniquely detected and in most cases characterized. This is a very important attribute in a process analytical enviromnent. 

Naturally, a fundamental requirement is the determination of the structure of the molecular sieves imder study (cf. Voliune 2) through techniques such as X-ray diffraction, neutron scattering, electron microscopy and so on. However, a remarkably broad variety of methods and tools are at our disposal for characterizing the physical and chemical properties of molecular sieves. Voliune 4 of the series Molecular Sieves - Science and Technology focuses on the most widely used spectroscopic techniques. Thereby, the contributions to this voliune not only review important applications of these techniques, but also comprise, to a greater or lesser extent, the basic principles of the methods, aspects of instrumentation, experimental handling, spectra evaluation and simulation, and, finally, employing spectroscopies in situ for the elucidation of processes with molecular sieves, e.g. synthesis, modification, adsorption, diffusion, and catalysis. 

Nanoaerosol can be sampled on a filter or grid for offline analyses of the morphology and composition of individual particles. The most common offline method is transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDX). However, the physical and chemical properties may change due to agglomeration and/or chemical reactions during the sampling, transport, and offline characterization processes. 

Most utility polymeric articles available today contain multiphase polymeric systems comprised of semi-crystalline polymers, copolymers, polymers in solution with low molar mass compounds, physical laminates or blends. The primary aim of using multicomponent systems is to mould the properties available from a single polymer to another set of desirable material properties. The property development process is complex and depends not only on the properties of the polymer(s) and other components but also on the formation process of the system which determines the developed microstmcture, and component interaction after formation. Moreover, the process of polymer composite formation and the stability of the composite is a function of environmental parameters, e.g., temperature, presence of other species etc. The chemical composition and some insight into the microscopic structure of constituents in a polymer composite can be directly obtained using Infrared (IR) spectroscopy. In addition, a variety of instrumental and sampling configurations for spectroscopic measurements combine to make irrfra-red spectroscopy a versatile characterization technique for the analysis of the formation processes of polymeric systems, their local structure and/or dynamics to relate to property development under different environmental conditions. In particular, Fourier transform infrared (FTIR) spectroscopy is a well-established technique to characterize polymers [1, 2]. 

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