Analysis of Tap Water Using ICDS™-40A Suppressor Unit

Importance of the Topic

Ion chromatography provides high-sensitivity detection of ionic species and is widely used for environmental, pharmaceutical, and food analysis. Accurate measurement of anions in drinking water is essential to ensure compliance with regulatory limits and to protect public health.

Objectives and Study Overview

This study demonstrates the analysis of five anions (fluoride, chloride, nitrite, chlorate, nitrate) in tap water according to Japanese MHLW regulations. Special focus is placed on achieving reliable quantitation of nitrite nitrogen at the low standard limit of 0.004 mg/L.

Methodology and Instrumentation

Anion separation was performed on a Shim-pack IC-SA4 column (150 mm × 4.6 mm I.D.) using a mobile phase of 1.7 mmol/L sodium carbonate and 5.0 mmol/L sodium hydrogen carbonate at 0.8 mL/min and 50 °C. A 50 µL sample volume was injected. Detection combined electroconductivity for most anions and UV-VIS at 210 nm for nitrite to avoid chloride interference.

Used Instrumentation

• Shimadzu ICDS-40A electrodialysis suppressor unit for continuous suppression and regeneration
• Shim-pack IC-SA4 analytical column
• Electroconductivity detector
• UV-VIS detector (210 nm)

Main Results and Discussion

Chromatograms of standard solutions confirmed baseline separation of five anions. Calibration for nitrite nitrogen over 0.004–0.040 mg/L yielded r² ≥ 0.999. Six replicate injections at 0.004 mg/L showed retention time RSD ≤ 0.12% and area RSD ≤ 3.07% (conductivity) and ≤ 1.10% (UV-VIS). Relative errors for standards were within ±3.87%. Analysis of tap water spiked at 0.004 mg/L demonstrated all analytes below regulatory limits.

Benefits and Practical Applications

• The ICDS-40A suppressor’s simultaneous suppression and regeneration shortens cycle time.
• High sensitivity enables quantitation at low regulatory thresholds.
• Dual detection ensures accuracy for both common anions and low‐level nitrite nitrogen.
• Method aligns with official drinking water quality standards for routine QC.

Future Trends and Potential Applications

Advancements may include coupling IC with mass spectrometry for broader anion profiling, integration into automated online monitoring systems for real-time water quality surveillance, miniaturized suppressor designs for field use, and application to emerging ionic contaminants in environmental samples.

Conclusion

A Shimadzu ICDS-40A based ion chromatography method reliably quantifies key anions in tap water, meeting stringent MHLW requirements, including trace nitrite nitrogen analysis, and offers rapid, high-precision performance for water quality laboratories.