Table of contents 1 Why is particle size important?

DYNAMIC LIGHT SCATTERING
Dynamic Light Scattering (DLS) is unique among the techniques described in 
this document. The primary result from DLS is typically the mean value from the 
intensity distribution (called the Z average) and the polydispersity index (PDI) to 
describe the distribution width. It is possible to convert from an intensity to a volume 
or number distribution in order to compare to other techniques. 
IMAGE ANALYSIS
The primary results from image analysis are based on number distributions. These 
are often converted to a volume basis, and in this case this is an accepted and valid 
conversion. Image analysis provides far more data values and options than any of 
the other techniques described in this document. Measuring each particle allows the 
user unmatched flexibility for calculating and reporting particle size results.
Image analysis instruments may report distributions based on particle length as 
opposed to spherical equivalency, and they may build volume distributions based on 
shapes other than spheres. 
Dynamic image analysis tools such as the CAMSIZER allow users to choose a variety 
of length and width descriptors such as the maximum Feret diameter and the 
minimum largest chord diameter as described in ISO 13322-2 (ref. 5). 
With the ability to measure particles in any number of ways comes the decision 
to report those measurements in any number of ways. Users are again cautioned 
against reporting a single value—the number mean being the worst choice of the 
possible options. Experienced particle scientists often report D10, D50, and D90, or 
include standard deviation or span calculations when using image analysis tools.
CONCLUSIONS
All particle size analysis instruments provide the ability to measure and report the 

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