Particle Size Distribution by Space or Time Dependent Extinction Profiles obtained by Analytical Centrifugation
Torsten Detloff, Titus Sobisch, Dietmar Lerche
Particle & Particle Systems Characterization, Volume 23, Issues 2, 2006, Pages 184-187, Special Issue: Particulate Systems Analysis, https://doi.org/10.1002/ppsc.200601028.
Research Topic:
The authors present the principles behind the ability of the LUMiSizer to obtain high-resolution particle size distributions.
Keywords: LUMiSizer; particle size analysis, analytical centrifugation, extinction profiles, particle size resolution, sedimentation, STEP-Technology
Paper Highlights:
There is something about well-written short papers—a quick read and readily digestible. This is one of those publications.
The paper aims to show how the STEP-Technology works for particle sizing. The authors chose two simple suspensions: 1) a bi-modal silica suspension and 2) a mon-modal polystyrene latex suspension. The STEP-Technology® (Space Time Extinction Profiles) measures the light extinction changes over time across the whole sample. In short, you measure the concentration changes in your dispersion as a function of time and space. The extinction-based optical profiles are usually displayed in transmission format.
Figure 1. displays a typical dispersion transmission-based fingerprinting showing a monomodal particle size dispersion. In addition to seeing the particles settle, you can also see what kind of sediment layer they form.
Figure 2. shows a beautiful example of a bi-modal suspension extinction profile and one of the main advantages of the STEP-Technology®. It takes advantage of Stokes's law and light scattering principles. Larger particles move faster than smaller ones, thereby forming distinct optical bands, which the software then analyzes and resolves for the correct particle size.
Figure 5 contains the density, and cumulative particle size distribution got the bi-modal silica suspension (280 nm and 550 nm).
The remainder of the paper discusses the ability to analyze particle size at set positions within the sample and across the whole product using the constant time method. Unless you are a STEP-Technology user, this part is probably not much use. :-)
