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Particle Sizing and Composition

CT Associates has built a strong reputation for thorough, innovative work in identifying and measuring particulate contaminants in high-purity liquids. We assess individual component cleanliness by measuring particle shedding in ultrapure water (UPW) and some process chemicals.  Our ability to capture and analyze particles using various analysis techniques helps identify and mitigate sources of contamination.  Using the liquid nebulization and condensation particle counting technology (developed by CTA), particle precursors and nanoparticles as small as 2.5nm can be measured in UPW. Shown below is an example of such measurements. A mixture of three different molecular weight polymers, for use as a surrogate of ion exchange resin degradation products, was studied for its stability over a 30 day aging period. 

Aging study of a mixture of three different molecular weight polymers (approximately 3, 5, and 8 nm)

particle size distribution of nanoparticle filter challenge

We also work closely with a variety of partner laboratories to leverage an even broader range of complementary capabilities.  CTA can design and execute test plans for many types of liquids (water, organic solvents or inorganic acids and bases).  Tests can include the careful collection of grab samples and the characterization through a wide range of particle sizes and compositions.


One example of this is the collection and concentration of waterborne contaminants into sub-millimeter spots on a variety of substrates, which enables a wider variety of surface analysis techniques to be used. This high spatial density allows for increased sensitivity and lower detection limits. An example of this process, as analyzed via SEM and EDS, can be found below.  In this case, contaminants were extracted from a UPW system with degrading IX resin. More information on this process and study can be found in a publication from the 2018 Ultrapure Micro Conference; THE USE OF FOCUSED AEROSOL DEPOSITION (FAD) TO CAPTURE, IDENTIFY AND QUANTIFY KILLER DEFECT PARTICLES IN UPW

Example of UPW system contaminants, during ion exchange degredation, deposited with Focused Aerosol Deposition (FAD), and subsequent evaluation via SEM and EDS

SEM image of contamination concentrated and captured using focused aerosol deposition
individual particles captured via focused aerosol deposition
EDX spectrum of microparticle
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