Fast Anion Determinations in Environmental Waters Using a High-Pressure Compact Ion Chromatography System

Importance of the Topic

Ion chromatography is a cornerstone technique for monitoring inorganic anions in environmental waters under regulations such as the U.S. Safe Drinking Water Act and Clean Water Act. Fast, reliable quantification of anions like fluoride, nitrate and sulfate is essential for public health, industrial discharge compliance, and water quality management.

Objectives and Study Overview

This study updates a previous application note by implementing a high-pressure compact IC system and a new 4 µm particle column format. The aim is to reduce analysis time from 16 min to 12 min while maintaining or improving separation efficiency, precision, and detection limits for seven common anions.

Methodology and Instrumentation

The method uses a Thermo Scientific Dionex Integrion HPIC system configured for Reagent-Free IC with the following key components:

• Dionex Integrion HPIC pump, degasser, suppressor compartment and conductivity detector
• Dionex EGC 500 KOH eluent generator cartridge with CR-ATC 600 trap column
• Dionex IonPac AG18-4 µm guard column (4 × 30 mm) and AS18-4 µm separation column (4 × 150 mm)
• Dionex AERS 500 self-regenerating suppressor (4 mm, recycle mode)
• Dionex AS-AP autosampler with 10 mL trays
• Chromeleon 7.2 SR4 chromatography data system

Chromatographic conditions employ a linear KOH gradient from 15 to 44 mM at 1.0 mL/min, column temperature 35 °C, detector compartment 15 °C, and 10 µL injections.

Main Results and Discussion

Seven anions were baseline‐resolved in under 9 min and fully eluted by 12 min. Method performance included:

• Retention time RSDs < 0.1 % and peak area RSDs < 0.2 %
• Method detection limits below 2 µg/L (except bromide at 2.6 µg/L)
• Linear calibration over 0.04–200 mg/L with R² > 0.9996
• Recovery of 89–105 % across diverse water matrices

The shorter 150 mm column with 4 µm resin delivers higher efficiency, better resolution of critical pairs, and reduced run time compared to the 250 × 7.5 µm format.

Benefits and Practical Applications

This fast IC method supports high-throughput monitoring of drinking water, wastewater, surface water and well water, enabling laboratories to meet regulatory compliance with improved sample throughput, minimal manual eluent preparation, and robust quantification.

Future Trends and Potential Uses

Advances in high‐pressure IC, sub-2 µm particle columns and miniaturized systems will further shrink analysis times. Integration with advanced detectors, automated sample handling and real-time data analytics will expand on-site water quality monitoring and process control in industrial and environmental applications.

Conclusion

The updated high-pressure IC method with a 4 µm column format achieves rapid, precise, and sensitive determination of seven inorganic anions in environmental waters in a 12 min run, demonstrating its value for routine regulatory and research laboratories.

References

1. U.S. EPA Method 300.1 Revision 2.2 Environmental Monitoring Methods 1997
2. Christison T Lopez L Rohrer J Fast Anion Determinations in Environmental Waters Using a High-Pressure Compact Ion Chromatography System Application Update 200 Thermo Fisher Scientific 2016
3. Thermo Fisher Scientific Application Note 154 Determination of Inorganic Anions in Environmental Waters Using a Hydroxide Selective Column 2003
4. Thermo Fisher Scientific Application Note 133 Determination of Inorganic Anions in Drinking Water by Ion Chromatography 2002