Johannes Walter, Christina Spruck · Tuesday, 25 August 2026, 16:45 – 18:45 · Session 8
Room 101125
Analytical ultracentrifugation (AUC) is perfectly suited for the analysis of particle size distributions (PSDs). However, the characterization of PSDs places high demands on any characterization technique. In sedimentation analysis, it must be taken into account that the sedimentation rate scales with the square of the particle size, and that contributions from scattering may need to be considered to determine accurate particle concentrations.
To address these challenges, we developed a selection of software tools. HDR-SVFIT enables the global and simultaneous analysis of sedimentation velocity data from multiwavelength AUC (MW-AUC) experiments across all measured wavelengths on a standard desktop computer in a short computation time. Our tool further introduces enhanced regularization techniques that allow regularization not only along the sedimentation coefficient dimension, but also along the wavelength dimension. This approach enables PSDs and sedimentation coefficient distributions to be determined with higher resolution, particularly for narrowly distributed samples, while avoiding the distribution broadening that conventionally results from regularization in the sedimentation coefficient dimension alone. Furthermore, the optical spectra of individual species can be readily extracted through high-resolution inspection of the sedimentation coefficient dimension.
Our tool ConVERT enables conversion of the retrieved sedimentation coefficient distributions into particle size distributions, with appropriate consideration of relative and absolute concentrations. A brief overview will further be given of HDR-MULTIFIT, a tool for the analysis of gravitational sweep experiments, which are beneficial for highly polydisperse samples.
The workshop will tackle the following topics:
- Determination of particle sizes and their distributions
- The influence of scattering and the role of Mie’s theory
- Correction of size distributions and their weighting
- Multiwavelength analysis of sedimentation and gravitational sweep experiments
- Concentration coupling experiments for polydisperse distributions
- Simultaneous analysis of size, density and refractive index increment using density variation
- Hands-on training on HDR-SVFIT and ConVERT