Determination of trace organic acids and inorganic anions in boric acid-treated power plant waters using an automated reagent-free ion chromatography system

Significance of the topic

In pressurized water reactors the coolant contains high levels of boric acid and lithium hydroxide to control reactivity and pH. Trace anions such as chloride, sulfate, and low molecular weight organic acids at sub-µg/L levels act as corrosion catalysts on fuel cladding and system components. Reliable determination of these impurities in borated waters is critical for corrosion control and operational safety.

Objectives and Study Overview

This work updates Application Note AN185 by incorporating a Thermo Scientific Dionex IonPac AS28-Fast-4 µm column, the Dionex ICS-6000 HPIC system, and improved consumables. The goal is to enhance peak efficiency, resolution, and ease of use in the automated, reagent-free determination of trace organic acids and inorganic anions in borated power plant waters.

Instrumentation Used

• Thermo Scientific Dionex ICS-6000 HPIC system (DP pump, DC detector/Chromatography module with conductivity detection, EG eluent generator)
• Dionex IonPac AG28-Fast-4 µm guard column and AS28-Fast-4 µm analytical column
• Dionex CR-CTC III continuously regenerated cation trap column for lithium removal
• Dionex ADRS 600 anion dynamically regenerated suppressor and CRD 200 carbonate removal device
• Dionex IonPac UTAC-ULP2 concentrator column for large volume injection
• Thermo Scientific AS-HV high volume autosampler with internal peristaltic pump
• Chromeleon Chromatography Data System software for method control and valve sequencing

Methodology

Samples containing up to 2 500 mg/L boron and 5 mg/L lithium were prepared in high-density polyethylene containers. A two-system approach was employed: System 2 removed lithium on the CR-CTC III column, then loaded samples or standards onto a 10-port valve loop (10 µL for calibration, 2 mL for samples) via the AS-HV autosampler. Deionized water transferred the loop contents to the UTAC-ULP2 concentrator. System 1 used an electrolytic KOH gradient (7–72 mM) generated in-line, separating fluoride, glycolate, acetate, formate, chloride, nitrite, bromide, nitrate, phosphate, and sulfate within 25 min. Suppressed conductivity detection quantified analytes. Method parameters such as flow rates, injection volumes, and valve timings were automated in Chromeleon programs.

Key Results and Discussion

A complete baseline separation of all target anions in deionized water was achieved in under 25 min. Method detection limits ranged from 0.006 to 0.054 µg/L (LOD) with quantification limits of 0.021–0.182 µg/L. Calibration curves were linear (r²≥0.9995) over relevant concentration ranges. Recoveries in borated matrices (1 000–2 500 mg/L boron) spiked with 2.5–100 µg/L anions were 90–110%. Retention time RSDs were <0.1% and area precision <3% across replicates.

Benefits and Practical Applications

• Reagent-free eluent generation ensures reproducible gradient delivery and reduces manual preparation errors.
• High-resolution AS28-Fast column resolves early eluting organic acids from borate matrix peaks, enabling accurate quantitation of formate and glycolate.
• Automated large volume injection via AS-HV autosampler minimizes sample handling and contamination risks.
• Method supports quality control in nuclear power plant water circuits, semiconductor rinse waters, and other high-purity water applications.

Future Trends and Opportunities

Advances may include coupling reagent-free IC with mass spectrometry for enhanced selectivity, further miniaturization of hardware for field-deployable systems, integration of real-time data analytics and AI-driven method optimization, and development of next-generation ion exchange materials to improve throughput and lifetime.

Conclusion

The updated method delivers robust, high-resolution analysis of trace organic acids and inorganic anions in boric acid-treated waters. Its automated, reagent-free design yields sub-µg/L detection, excellent precision, and accuracy across a wide dynamic range. This approach enhances operational safety and efficiency in power generation and other industries requiring high-purity water monitoring.

References

• Nordmann F. Aspects of Chemistry in French Nuclear Power Plants. Proceedings of the 14th International Conference on the Properties of Water and Steam; 2004:521–530.
• Thermo Scientific Application Note AN185: Determination of Trace Organic Acids and Inorganic Anions in Boric Acid-Treated Power Plant Waters.
• Thermo Scientific Technical Note 73982: Techniques for Successful Trace Anion and Cation Determinations in High Purity Waters.
• Thermo Scientific Dionex ICS-6000 Ion Chromatography System Operator’s Manual; 2018.
• Thermo Scientific Dionex IonPac AS28-Fast-4 µm Column Manual.
• ICH Guideline Q2B, Validation of Analytical Procedures: Methodology; 1996.