Understanding Nanoparticle Contamination in Ultrapure Water: Improvements in Monitoring through Filter Studies

Understanding Nanoparticle Contamination in Ultrapure Water: Improvements in Monitoring through Filter Studies

Particle Measuring Systems has been leading the developing of particle metrology for decades, starting with the invention of laser-based particle counting in 1972. Working together with Intel, the methodology was improved to measure nanoparticles in one of the cleanest liquids in the world, ultrapure water. In this blog, we share the results of two case studies of UPW nanoparticle counters.

Cartridge Filter Age Study: Nanoparticle Contamination in Ultrapure Water:

Water Particle Counter Ultra di 20In a parallel grouping of filters, six identical feeds of ultrapure water were set up to pass through each filter bank. The Ultra DI® 20 liquid particle counters were used to measure the particle count pre- and post-filtering before reaching a common outlet. This data would later be used to measure filter efficiency.

The testers were not aware of filter age for the study. However, when re-ordering the collected data by filter age, a strong correlation between increasing particles and older filters was seen. The older filters were also found to not be as effective with particles ranging from 20 to 50 nm. Due to the high quality of ultrapure water, the Ultra DI 20’s sensitivity range of 20 to 100 nm was better suited to the application.

When monitoring at 20 nm, losses in filter performance can be seen early.  If using an older filter, you’re likely not capturing many nanoparticles smaller than 50 nm.

Ultrafilter Age Study

The Ultra DI counters were able to tell cartridge filters apart, but what about ultrafiltration (UF) skids? In this study, three UF skids with different operational use were tested using the Ultra DI 20. Counts were taken at the same post-filtration point for each skid without knowledge of the age.

Like cartridge filters, ultrafilters were also distinguishable by their length of use. The filters also lost efficiency over time.

Future Case Studies of Nanoparticle Contamination in Ultrapure Water:

From the results, filter performance is strongly linked to the duration of use. Measurement of 50 nm contamination provides a reliable method of vetting a filter, but there are advantages to capturing smaller sizes in the data. Particle counts at the 20 nm level changed much earlier than at 50 nm. This enables operators to track changes in particle trends and make quality decisions sooner and more proficiently. The quality of the product itself may even be redefined, helping entire systems to improve.

But the studies continue! Promising results from new tests reveal more insight into possible improvements and advanced applications. Engineered and optimized with the latest technology, the optical particle counters from Particle Measuring Systems continue to raise the bar for excellence in particle metrology.

To learn more about these studies of our liquids particle counters,  watch the full 2020 Ultrapure Micro presentation:


Particle Measuring Systems is the only manufacturer of true and reliable 20 nm particle counters for chemicals and ultrapure water. Find the right liquid particle counter for your application or get a quote.

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