Ion Chromatography with Electrolytically Regenerated Suppressor for Water Analysis

Importance of the Topic

The analysis of inorganic anions and disinfection byproducts in water is critical for environmental monitoring, regulatory compliance and public health.
Ion chromatography with suppressed conductivity detection offers the sensitivity and selectivity required for trace-level determination of regulated anions according to EPA Methods 300.0 and 300.1.

Study Objectives and Overview

This study evaluates a Shimadzu modular ion chromatography system equipped with an electrolytically regenerated suppressor for the determination of common inorganic anions and disinfection byproducts in water. The objectives were:

• To assess method performance for seven common anions (F-, Cl-, NO2-, Br-, NO3-, PO43-, SO42-) following EPA 300.0/300.1 Part A
• To develop high-resolution methods for simultaneous analysis of common anions and DBPs (ClO2-, BrO3-, ClO3-)
• To demonstrate reproducibility, sensitivity and resolution under varying chromatographic conditions

Methodology and Instrumentation

The experimental setup comprised a Shimadzu modular IC system with an electrolytic suppressor operating at 60 mA in recycle mode. Separation was achieved on quaternary ammonium columns under two conditions:

1. Part A method: 250×4 mm, 9 μm column, eluent 1.8 mM Na₂CO₃/1.7 mM NaHCO₃, 1.0 mL/min, 50 μL injection
2. High-resolution methods: 250×4 mm, 5 μm column, eluents of Na₂CO₃/NaHCO₃ gradients, 0.8 mL/min flow

The suppressor reduced background conductivity, enhancing detection limits from low ppm to low ppb.

Main Results and Discussion

For the Part A method, calibration was linear with R² ≥ 0.999 over 0.05–20 ppm (0.1–100 ppm for chloride). Retention time RSDs were 0.02–0.08% and peak area RSDs 0.23–0.42% across four days.
High-resolution methods achieved separation of ten anions in under 20 minutes. Method A yielded faster runs, while Method B provided improved bromide and chlorate resolution, suitable for trace-level DBP analysis.

Benefits and Practical Applications

The Shimadzu system with electrolytically regenerated suppression offers:

• Enhanced sensitivity to low ppb levels
• Robust reproducibility over extended sequences
• Flexibility to switch between rapid and high-resolution analyses
• Compliance with EPA regulatory methods

Future Trends and Opportunities

Emerging needs in water analysis will drive further improvements:

• Integration of real-time data processing and automated calibration
• Miniaturized and field-deployable IC systems
• Advanced suppressor technologies for even lower detection limits
• Expanded scope to include emerging contaminants and organic ions

Conclusion

The study confirms that electrolytically regenerated suppression in ion chromatography provides reliable, high-sensitivity analysis for regulated anions and DBPs. The adaptable Shimadzu IC platform effectively meets EPA method requirements and supports both rapid screening and high-resolution trace analysis.

References

Hui Guo, Craig Young, Steve Maury, Ruth Marfil-Vega. Ion Chromatography with Electrolytically Regenerated Suppressor for Water Analysis. Shimadzu Scientific Instruments, Inc.