Trace analysis of monovalent cations in ethanolamine matrix (secondary circuit of a pressurized water reactor) applying Metrohm Inline Sample Preparation with an 800 Dosino for liquid handling

Significance of the Topic

In pressurized water reactors, monitoring trace cations such as lithium, sodium and ammonium in the secondary circuit is critical to control corrosion and maintain water chemistry stability. Ethanolamine is commonly used as a pH control agent, and its presence complicates trace analysis due to matrix effects.

Objectives and Study Overview

This study demonstrates a rapid and sensitive approach for quantifying low microgram per liter levels of monovalent cations in an ethanolamine-containing water matrix. The method integrates inline preconcentration with cation chromatography for efficient sample handling.

Methodology and Instrumentation

• Sample matrix: Simulated secondary circuit water from a pressurized water reactor containing ethanolamine.
• Inline preconcentration: Metrohm Inline Preconcentration using the 800 Dosino for automated liquid handling and large volume injections.
• Chromatographic separation: Metrosep C2-250 analytical column with Metrosep PCC 1 HC preconcentration column.
• Eluent composition: 4.0 mmol/L tartaric acid and 0.1 mmol/L dipicolinic acid at 1.0 mL/min flow rate.
• Detection: Direct conductivity detector.

Main Results and Discussion

The method achieved limits of quantification of 0.8 µg/L for lithium and sodium and 200 µg/L for ammonium in the ethanolamine matrix. Precision over six replicate analyses yielded relative standard deviations of 0.6% for lithium, 1.5% for sodium, and 0.4% for ammonium. Ethanolamine was quantified at 2000 µg/L with 0.2% RSD. Chromatographic profiles showed clear separation of target cations from the organic matrix within a 13-minute runtime.

Benefits and Practical Applications

• Enhanced sensitivity through automated inline preconcentration enables trace-level detection without extensive manual sample preparation.
• High precision and reproducibility support reliable monitoring of water chemistry in power plant operations.
• Automated workflow reduces hands-on time and potential sources of error.

Future Trends and Potential Uses

Ongoing developments may integrate inline sample preparation with mass spectrometric detection for improved selectivity. Advances in microfluidic separation and remote monitoring could further streamline process analytics in industrial water treatment. Combining chemometric approaches with real-time data feeds may enhance predictive maintenance in nuclear power applications.

Conclusion

This study presents a robust, automated cation chromatography method for trace analysis of lithium, sodium and ammonium in ethanolamine matrices. The inline preconcentration approach provides high sensitivity, precision and throughput, making it suitable for quality control and monitoring in pressurized water reactor secondary circuits.

Reference

• Metrohm AG IC Application Note No C-96 Trace analysis of monovalent cations in ethanolamine matrix secondary circuit of a pressurized water reactor applying Metrohm Inline Sample Preparation with an 800 Dosino for liquid handling