Light and Electron Microscopy

Microscopic techniques have a long history in pharmaceutical formulation research and development. They are especially useful for the study of systems containing particles of different length scales (like powders, granules, or colloidal suspensions) but can also be employed for the study of compact solid forms like tablets or of semisolids. As they yield a visual impression of the object of study they provide a rather natural way to the comprehension of sample behavior. As with all analytical techniques, however, there may be limitations and pitfalls that should be known in order to employ the methods correctly. This chapter explains the basic features of the microscopic techniques traditionally employed in pharmaceutical research—optical light microscopy as well as scanning and transmission electron microscopy with their respective variations. Apart from a short overview on instrumentation, the different sample preparation techniques are explained and a selection of pharmaceutical application examples is provided to illustrate the wealth of information that can be obtained and to stimulate a more detailed exploration of the possibilities of these fascinating methods.