Low-Cost Determination of Anions in Municipal Drinking Water Using EPA Method 300.0 and the Dionex ICS-900 IC System

Importance of the Topic

Accurate measurement of inorganic anions in municipal drinking water is essential for regulatory compliance and public health protection. EPA Method 300.0 identifies key anions such as fluoride, chloride, nitrite, sulfate, bromide, nitrate, and phosphate. Excessive concentrations of some anions can pose health risks or affect water quality.

Study Objectives and Overview

This work evaluates the performance of Thermo Scientific Dionex ICS-900 IC system for routine determination of seven inorganic anions in municipal water, following EPA Method 300.0. Raw drinking water from San Jose, California was analyzed without any sample pretreatment to demonstrate method robustness.

Methodology

• Anion separation was performed using Dionex IonPac AG22 guard and AS22 analytical columns at ambient temperature.
• The eluent consisted of 4.5 mM sodium carbonate and 1.4 mM sodium bicarbonate at a flow rate of 1.2 mL/min.
• Injection volume was 25 µL and detection was achieved by suppressed conductivity with an AMMS 300 MicroMembrane suppressor regenerated with 50 mM sulfuric acid.
• Data acquisition and system control were managed using Chromeleon Chromatography Data System software.

Used Instrumentation

• Dionex ICS-900 IC system
• Dionex AS-DV Autosampler
• Dionex IonPac AG22 guard column and AS22 analytical column, 4 mm
• Thermo Scientific Dionex AMMS 300 Anion MicroMembrane suppressor
• Chromeleon Chromatography Data System software

Key Results and Discussion

All seven target anions were baseline separated within a 13-minute runtime. The drinking water sample contained chloride (98.1 mg/L) and sulfate (48.2 mg/L) as the most abundant species, while phosphate, nitrate, bromide, nitrite, and fluoride were detected at trace levels (3.12, 2.43, 1.22, 0.54, and 0.19 mg/L, respectively). These concentrations comply with EPA National Primary and Secondary Drinking Water Regulations.

Benefits and Practical Applications

• Fast three-minute analyte separation enables high sample throughput for routine monitoring.
• Low maintenance IC system design minimizes downtime and operational costs.
• Suppressed conductivity detection ensures high sensitivity and stable baselines.
• Direct analysis of untreated water simplifies workflow and reduces sample preparation time.

Future Trends and Potential Applications

Ongoing developments in ion chromatography instrumentation and suppressor technologies promise even faster analysis and lower detection limits. Integration with automated sample handling and remote diagnostics will further streamline water quality monitoring in municipal and industrial settings.

Conclusion

The Dionex ICS-900 IC system meets EPA Method 300.0 requirements for accurate and reliable determination of inorganic anions in drinking water. Its robust design and efficient operation make it an ideal choice for routine environmental analysis laboratories.

References

• U.S. EPA Method 300.0, Revision 2.1, U.S. Environmental Protection Agency, Cincinnati, OH, 1993.
• Thermo Scientific Dionex Application Note 133.2, Determination of Inorganic Anions in Drinking Water by Ion Chromatography, 2004.