Analytical Ultracentrifugation (AUC) is used to analyse biological molecules in specially designed centrifuges, which can separate a biological molecule into its multimeric states. The sedimentation rate of the molecule is monitored continuously to produce a molecular weight profile of the species observed and, hence, the multimeric state(s) of that molecule, including determining whether aggregation is present. Equilibrium analysis can also be performed, to provide dynamic equilibrium information i.e. association/dissociation rates of the multimeric states.
This method is used in preference to methods that may provide ambiguous results, such as size-exclusion chromatography (SEC) that usually requires additional analyses to determine molecular weight of any UV absorbing peaks and hence multimeric/aggregate states.
The ICH Q6B guidelines, for characterisation and confirmation of biopharmaceuticals in support of new marketing applications, consider aggregation to be a product-related impurity and state that analytical procedures should be developed and justified to measure changes in the drug substance during manufacture and storage. Aggregates should be resolved and quantitated using appropriate techniques.
M-Scan Brochure: Biotechnology and Pharmaceutical Analysis (8pp.)