Size Exclusion Chromatography a Useful Technique For Speciation Analysis of Polydimethylsiloxanes

Size exclusion chromatography (SEC) is one of the most popular methods for separation and molecular characterization of natural or synthetic macromolecules mixtures. This chapter describes the retention mechanisms for SEC as ideal size-exclusion, which separates molecules primarily on the basis of their hydrodynamic volume, and non-ideal size-exclusion, which depends on entropic and enthalpic retention mechanisms and applies when adsorption occurs. Furthermore, recent applications of SEC in the biomedical and pharmaceutical sciences are shown. Finally, the use of SEC as a technique for speciation analysis of polydimethylsiloxanes (PDMS) is presented. PDMS belong to polysiloxanes, with the common name silicones, and are used in a wide variety of applications, such as in the medical (e.g. implants), pharmaceutical (e.g. the active pharmaceutical substances dimeticone and simeticone) and food (e.g. the food additive E 900) areas. Speciation analysis of this polymer is very important, because the degree of polymerization and the particle size, (or molecular weight) have experimental impacts on the toxicity, absorption and migration in living organisms.