Municipal Drinking Water Analysis by Fast IC

Importance of the topic

Determining inorganic anions in municipal drinking water is essential for ensuring compliance with regulations such as the US Safe Drinking Water Act and safeguarding public health. Fast, reliable analysis supports routine monitoring and quality control in water treatment facilities.

Objectives and study overview

The aim was to evaluate a fast ion chromatography method using the Dionex IonPac AS22-Fast column to separate seven common inorganic anions (fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate) at mg/L levels in municipal water. The performance was compared to EPA Methods 300.0 and 300.1 in terms of analysis speed and reliability.

Methodology

Sample preparation involved filtration of municipal drinking water through a 0.45 µm syringe filter. Chromatographic separation used a 2×150 mm Dionex IonPac AS22-Fast column at 30 °C with a carbonate eluent (4.5 mM Na₂CO₃, 1.4 mM NaHCO₃) at 0.5 mL/min and a 2.5 µL injection volume. Suppressed conductivity detection was conducted with a Dionex ASRS 300 suppressor operating at 16 mA.

Instrumentation

• Thermo Scientific Dionex ICS-1100 Integrated IC System with electrolytic suppression
• AS Autosampler
• Thermo Scientific Dionex Chromeleon Chromatography Data System software

Main results and discussion

All seven anions eluted within 5 minutes, achieving complete baseline separation and accurate quantification. Measured concentrations in the municipal sample were: fluoride 0.4 mg/L, chloride 99.5 mg/L, nitrite 2.7 mg/L, bromide 1.8 mg/L, nitrate 4.3 mg/L, phosphate 8.9 mg/L, sulfate 51.8 mg/L. The fast cycle time and electrolytic suppression lowered background noise and reduced total analysis time.

Benefits and practical applications

• Run time under 5 minutes increases sample throughput
• Reduced cycle time lowers operational costs and reagent use
• Compliance with EPA 300.0 and 300.1 requirements
• Can be implemented on various Dionex IC platforms, including reagent-free IC systems

Future trends and potential applications

Ongoing advances in column materials and detector technologies are expected to further shorten analysis times and enhance sensitivity. Integration with automated and real-time monitoring systems will facilitate continuous water quality assessment. Stricter regulatory limits may drive method developments for lower detection thresholds and broader anion panels.

Conclusion

The Dionex IonPac AS22-Fast column offers a rapid, reliable alternative to established EPA methods for inorganic anion determination in drinking water, reducing cycle time and operational costs while maintaining compliance and accuracy.

References

1. Federal Register, 2010; Vol. 75, No. 184.
2. U.S. EPA Method 300.0 Revision 2.1, 1993.
3. U.S. EPA Method 301.0 Revision 1.0, 1997.
4. Dionex Application Note 133, Determination of Inorganic Anions in Drinking Water by Ion Chromatography, 2004.