Analytical ultracentrifugation (AUC) is a specialized technique used for studying the physical properties of macromolecules and complexes in solution. It involves the centrifugation of a sample in a specialized instrument that measures the sedimentation rate of the molecules which provides information about their size, shape, and mass. AUC is a powerful tool for biophysical characterization and is widely used in fields such as biochemistry, biophysics, and molecular biology. However, it requires specialized expertise and equipment, making it a relatively complex and costly technique to perform.