PURELAB® Chorus 1 The Efficient Use of Ultraviolet (UV) Light

Importance of UV Purification and TOC Monitoring

Ultra pure water is essential in laboratories and industry to avoid interference from organic and microbial impurities. UV light at short wavelengths offers a proven approach to reduce bacteria and degrade organic carbon. Continuous monitoring of total organic carbon provides a broad indicator of water quality, preventing contamination that can compromise analytical methods such as HPLC and mass spectrometry.

Study Overview

This compilation reviews multiple technology notes from ELGA LabWater, focusing on the role of 185nm and 254nm UV irradiation in water purification and the integration of TOC and resistivity monitoring in purification systems. The objective is to evaluate the performance requirements of online monitors and to outline control strategies for different impurity classes.

Methodology and Used Instrumentation

UV lamps are characterized by their intensity and exposure, expressed in microwatt seconds per square centimeter, with performance declining due to lamp aging and quartz fouling. Water purity is assessed using:

• Built in inline resistivity cells for ionic contaminants
• Ultraviolet oxidation at 185nm for organic carbon reduction
• Online TOC monitors for continuous organic content tracking
• Absolute filters, ultrafilters, microfilters, and vacuum degassers for particles, bioactive species, bacteria, endotoxins, and dissolved gases

Key instrument: PURELAB Chorus 1, equipped with a dual wavelength 185nm/254nm UV lamp to ensure combined disinfection and organic oxidation.

Key Findings and Discussion

Shortwave UV at 254nm effectively disrupts microbial DNA and RNA, while 185nm UV generates reactive oxygen species that cleave organic bonds, reducing TOC. Continuous TOC measurement is more critical than absolute accuracy, as it detects sudden changes in contamination that can affect sensitive analyses. Online resistivity monitoring controls ionic purity up to the 18.2 Mohm·cm limit.

Practical Benefits and Applications

The integration of UV treatment and real time TOC and resistivity monitoring delivers:

• Reliable maintenance of water quality for analytical and QA/QC processes
• Early detection of impurity excursions to protect instruments and assays
• Compliance with regulatory and laboratory standards

Future Trends and Applications

Advances are expected in lamp materials to extend UV transmission and reduce solarization effects. Integration of multiparameter sensors and machine learning algorithms will enhance predictive maintenance and further minimize manual interventions. Developments in photooxidation techniques could enable targeted removal of specific organic classes.

Conclusion

Combining shortwave UV irradiation with continuous TOC and resistivity monitoring provides a robust strategy to ensure ultrapure water quality. The PURELAB Chorus 1 system exemplifies this integrated approach, safeguarding analytical workflows and laboratory processes.

References

• ELGA LabWater/VWS (UK) Ltd. Technology Note 36, 2013
• ELGA LabWater. Technology Note 29
• ELGA LabWater. Technology Note 17
• ELGA LabWater. Technology Note 7