Fast determination of anions in municipal drinking water using a compact ion chromatography system with a chemically regenerated suppressor

Importance of the Topic

Ion chromatography remains a key tool for reliable detection of inorganic anions in water sources under regulatory frameworks such as the US Safe Drinking Water Act and Clean Water Act. Rapid, accurate, and high-throughput analysis of species like fluoride, nitrate, and sulfate is essential for public health monitoring and compliance testing.

Objectives and Study Overview

This application note demonstrates a fast and economical protocol for determining seven common inorganic anions in municipal drinking water using a compact, single-channel Dionex Inuvion ion chromatography system equipped with a chemically regenerated suppressor and high-efficiency IonPac AS22-Fast-4µm column.

Methodology and Applied Instrumentation

Drinking water samples were analyzed alongside standard mixtures using degassed deionized water as a diluent. The optimized separation employed a 4.5 mM sodium carbonate/1.4 mM sodium bicarbonate eluent at 2.0 mL/min, 30 °C column temperature, and a 10 µL injection volume. Suppressed conductivity detection was performed with a chemically regenerated ACRS 500 suppressor, regenerated online with 50 mM sulfuric acid delivered by an integrated peristaltic pump.

• Dionex Inuvion IC system with peristaltic suppressor regeneration
• Thermo Scientific AS-DV autosampler with 5 mL PolyVials and filter caps
• Dionex IonPac AS22-Fast-4µm and AG22-Fast-4µm guard column set (4 mm i.d.)
• Thermo Scientific Chromeleon CDS version 7.3.2

Main Results and Discussion

Seven anions—fluoride, chloride, nitrite, bromide, nitrate, phosphate, and sulfate—were fully resolved in under 5 minutes, enabling hourly sample throughput. Limits of detection and quantification met criteria for compliance monitoring. Analysis of a municipal drinking water sample revealed chloride at 9.5 mg/L, nitrate at 1.2 mg/L, sulfate at 16.5 mg/L, with fluoride (0.6 mg/L) and nitrite (0.2 mg/L) below regulated maximum contaminant levels.

Benefits and Practical Applications

The integrated Inuvion system offers a compact footprint, simplified suppressor maintenance, and reduced reagent consumption, supporting routine QA/QC in environmental and industrial laboratories. Its rapid cycle time allows more samples per shift without sacrificing resolution or sensitivity.

Future Trends and Opportunities

Ongoing developments may include microbore columns for further speed and solvent savings, coupling IC with mass spectrometry for enhanced specificity, and integration into automated, networked laboratory workflows for real-time water quality monitoring.

Conclusion

The compact Dionex Inuvion platform coupled with a chemically regenerated suppressor and AS22-Fast column delivers a fast, reliable, and cost-effective solution for routine inorganic anion analysis in drinking water.

References

1. National Primary Drinking Water Regulations, US EPA.
2. U.S. EPA Method 300.1: Determination of Inorganic Anions in Water by IC, 1997.
3. Thermo Scientific application notes on inorganic anion analysis by EPA 300.0 & 300.1.
4. The Dionex IonPac AS22-Fast-4µm IC columns specification.