Overview:

Analytical Ultracentrifugation (AUC) is a fractionating technique, which separates nanoparticles and polymers according to size, density and shape in any solvent. It covers the entire colloidal size range from particle sizes less than 1 nm to a few micrometers. The samples can be detected via their UV/Vis absorption, turbidity or refractive index with high statistical relevance since every particle is detected. Due to the fractionation of the sample, polydispersity is no problem. For small nanoparticles < 10 nm, the size resolution is very high and particle size distributions can be determined with Angstrom size resolution.

In this Webinar, I will briefly introduce AUC, sedimentation velocity experiments and how to determine the particle size distribution. In the following, examples will be discussed for: 1) polydisperse particles, 2) high resolution particle size distributions for small nanoparticles, 3) nucleation of nanoparticles in the AUC cell, 4) comparison of AUC with electron microscopy and static light scattering and finally 5) a newly developed UV/Vis detector and its application to determine the optical properties of quantum dots in dependence of particle size with Angstrom resolution.

Key Learning Objectives:

• Basics of Analytical Ultracentrifugation and sedimentation velocity

• Application of AUC to determine particle size distributions

• High resolution characterization of early species in nucleation reactions

• Application of AUC with spectrum detection for characterization of particle size/shape and optical properties of nanoparticles in a complex mixture

• Strengths and weaknesses of AUC compared to electron microscopy and static light scattering for particle size distribution determination