Capillary-Based Techniques for Physical-Chemical Characterization of Drug Substances and Drug Delivery Systems
Physical chemical characterization of drug compounds and drug delivery systems is challenging when the amount of material for analysis is limited. Capillary-based methodologies based on capillary electrophoresis (CE) or Taylor Dispersion Analysis (TDA) present a number of advantages as they are characterized by being fast, require a very limited amount of sample material, are easy to automate and highly versatile. Different methods may be applied leading to a range of physical chemical properties being probed for the same sample using the same instrumentation. The term affinity CE covers a range of approaches for assessing important physical chemical parameters such as non-covalent affinity constants, pKa values as well as partition/distribution coefficients measured by quantifying partitioning into microemulsions and micelles. On the other hand, TDA provides data on diffusivities and hydrodynamic radius as well as viscosity. A variant of this technique termed Flow Induced Dispersion Analysis (FIDA) may be used to quantify non-covalent affinity interactions for charged as well as neutral species. The present chapter highlights novel features of capillary based methods in profiling physical chemical properties of drug compounds and drug delivery systems. A number of feasible applications are described, which may serve as an inspiration in delivery science and technology.
KeywordsCapillary electrophoresis Taylor dispersion analysis Diffusion coefficient Hydrodynamic radius Affinity constant pKa Affinity shift capillary electrophoresis Partition coefficient
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