What variables can affect accuracy of sedimentation and diffusion coefficient calculations?

  • Location between the two menisci (i.e., it must be properly selected)
  • Density of the solvent
  • Temperature (affects viscosity)
  • Concentration dependency (pure, non-associating solutes show a decrease in sedimentation coefficient with an increase in concentration)
  • Radial dilution due to sector shapes
  • Boundary analysis (concentration and shape)
  • Speed dependence (sedimentation coefficient may increase with speed increase, and result in solute aggregation)
  • Primary electrostatic charge of solute and solvent
  • Association reactions that might occur between molecules as molecular weight increases