Real Time TOC System in the PURELAB® Chorus 1

Significance of Real-Time TOC Monitoring

Monitoring Total Organic Carbon (TOC) provides a broad measure of organic contaminants in purified water, complementing resistivity measurements of ionic impurities. Continuous TOC tracking ensures that ultrapure water quality remains within required standards and flags any sudden influx of organic load during use.

Objectives and Overview

This study presents the integration of a real-time TOC monitoring system into the PURELAB® Chorus 1 laboratory water purifier. The aim is to demonstrate rapid organic purity assessment and compare its performance with conventional TOC analyzers.

Methodology

The system measures water resistivity before and after exposure to UV photoxidation. Organic carbon compounds are oxidized to carbon dioxide, causing a change in solution conductivity. TOC is calculated from the resistivity difference between pre- and post-oxidation measurements.

Used Instrumentation

• PURELAB® Chorus 1 recirculation and dispensing module
• Conductivity/resistivity sensors upstream and downstream of UV reactor
• High-intensity UV lamp for photoxidation
• Flow-through sampling cell integrated into purification loop

Key Results and Discussion

The real-time TOC monitor updates every two seconds during recirculation or dispensing, in contrast to six to eight minutes required by standard analyzers. Comparative testing against a Sievers 820 TOC analyzer showed close agreement across a range of concentrations:

• At 1 ppb TOC: Chorus 1 = 1.0 ppb, Sievers 820 = 1.7 ppb
• At 3 ppb TOC: Chorus 1 = 3.0 ppb, Sievers 820 = 3.2 ppb
• At 5 ppb TOC: Chorus 1 = 5.0 ppb, Sievers 820 = 5.0 ppb
• At 9 ppb TOC: Chorus 1 = 9.0 ppb, Sievers 820 = 9.1 ppb

These results confirm that the real-time system delivers accuracy comparable to laboratory analyzers while providing immediate feedback.

Benefits and Practical Applications

• Instant detection of organic contamination spikes
• Assured water purity before critical dispensing tasks
• Enhanced process control in sensitive applications (e.g., molecular biology, semiconductor rinsing)
• Reduced downtime by identifying system maintenance needs early

Future Trends and Potential Applications

Advancements may include integration with digital data platforms for trend analysis, miniaturized sensor arrays for multi-parameter monitoring, and alternative oxidation techniques such as advanced oxidation processes (AOPs) to improve sensitivity for low-level organics.

Conclusion

The PURELAB® Chorus 1 real-time TOC system offers a rapid, reliable, and accurate method for tracking organic purity in ultrapure water. By delivering results in seconds, it empowers laboratories to maintain rigorous quality control and respond immediately to contamination events.