Highest Resolution for Nanoparticles
The Centrifugal or Sedimentation Field-Flow Fractionation is a technique which is ideally suited for the characterization of nanoparticles with highest resolution. Sedimentation Field-Flow Fractionation can separate nanoparticles by size and density in the range of 50 nm up to several µm. In case of very dense particles, such as gold sols, particles down to 10 nm can be analyzed. Two identically sized particles can be still separated by Sedimentation Field-Flow Fractionation into two peaks, when the density is different. Sedimentation Field-Flow Fractionation was invented und first published by Prof. Giddings.
The Centrifugal Force Separates the Nanoparticles
In Sedimentation Field-Flow Fractionation the separation force is established by a centrifugal field, which is generated by spinning the complete circular Sedimentation Field-Flow Fractionation channel at a high rate. The bigger and denser particles are forced more in the direction of the bottom wall (outer wall) than the smaller particles. Thus the bigger particles are eluted later from the Sedimentation Field-Flow Fractionation channel as they are located in slower streamlines in the channel than the smaller particles which are located in faster stream lines. Typical spinning rates which are used in Sedimentation Field-Flow Fractionation go up to 2500 rpm. To ensure a high resolution over a broad size range, spinning gradients are used for the Sedimentation Field-Flow Fractionation separations as well.
