Chapter 3 - Solid-State Characterization and Techniques

Abstract

Solid-state characterization allows scientists to understand the properties of formulation and formulation components, the first step in rational formulation development. Analytical technique measures response(s) to perturbation(s) of the objects under examination. The perturbation could be thermal, mechanical, light, radio frequencies, electromagnetic fields, or a combination thereof. Information extracted from their responses allows one to infer properties of the objects. It is therefore important to probe a system of interest from different angles, and it is the combined knowledge that forms a more comprehensive understanding of the system. This is particularly important for pharmaceutical solids, where the slow molecular mobility and heterogeneity results in weaker and variable responses. This chapter highlights some of the basic characterization tools for pharmaceutical solids, including microscopy (optical, electron, and probe microscopy), power X-ray diffraction, thermal analysis (differential scanning calorimetry, thermogravimetric analysis, and microcalorimetry), vibrational spectroscopy (infrared, Raman), solid-state NMR, moisture sorption and highlights some hyphenated techniques. The aim is to familiarize pharmaceutical scientists with the basic principles and typical applications of these commonly employed analytical tools for characterization of pharmaceutical solids.