Water quality testing with EPA 300.1

Significance of the Topic

Reliable monitoring of inorganic anions and disinfection byproducts (DBPs) in drinking water is critical to protect public health and meet regulatory requirements. Chronic exposure to DBPs such as chlorite and bromate has been linked to cancer and reproductive issues. Standard methods like U.S. EPA 300.1 and ISO 10304 are widely adopted, but their traditional two-run approach for major anions and trace DBPs reduces throughput and introduces manual handling errors.

Objectives and Study Overview

This study demonstrates a single-run ion chromatography method that combines EPA 300.1 Parts A and B (major anions and DBPs) and ISO 10304-1/4 requirements. The goals are to streamline analysis, automate eluent generation, maintain analytical performance across a wide concentration range, and improve laboratory efficiency and sustainability.

Methodology

The validation employed four water types: two tap, one artificial tap, and one commercial mineral sample. Samples and standards were prepared per EPA 300.1, including addition of 50 mg/L ethylenediamine (EDA) for chlorite stabilization. Calibration used a single standard solution covering fluoride, chlorite, bromate, chloride, nitrite, bromide, chlorate, nitrate, dichloroacetate, sulfate, and phosphate. Variable injection volumes (4–200 μL) via Metrohm intelligent Partial-Loop Injection Technique (MiPT) generated a precise calibration series. Sample injections were fixed at 50 μL and analyzed in quadruplicate.

Used Instrumentation

• 948 Continuous IC Module CEP for automated KOH eluent generation with on-demand electrolysis of ultrapure water and high-purity KOH concentrate
• 930 Compact IC Flex Oven/SeS/PP with sequential suppression and peristaltic pump regeneration
• Metrosep A Supp 21 – 250/4.0 column and guard for high-capacity hydroxide eluents at 45 °C
• 858 Professional Sample Processor
• IC Conductivity Detector MB with MSM-HC Rotor A suppressor for low baseline and high sensitivity

Main Results and Discussion

The method achieved baseline separation of all analytes within 40 min using an 18–80 mmol/L KOH gradient. Critical resolutions exceeded ISO requirements (average R > 1.9 for chlorite/bromate and R > 2.1 for bromide/chlorate; >3 for bromate with 500 mg/L chloride). Calibration linearity covered trace to major concentrations (fluoride to 400 μg/L; anions to 40 mg/L). Method detection limits met EPA 300.1 criteria. Repeatability showed RSDs below 2.5% for most ions (<5% for chlorite/bromate). Matrix tolerance tests confirmed no significant interference from up to 500 mg/L chloride or sulfate, and early-eluting organics such as glycolate did not coelute with fluoride.

Benefits and Practical Applications

• Single-run determination of major anions and DBPs reduces analysis time and sample handling
• Automated KOH eluent generation eliminates manual reagent preparation and enhances reproducibility
• High-capacity column and sensitive detection deliver low detection limits and stable retention times
• Sustainable operation with minimal reagent waste and high throughput suitable for routine water testing laboratories

Future Trends and Applications

Advancements may include integration with remote or inline water monitoring systems, further miniaturization of IC platforms, and coupling with data-driven quality control tools. Expansion to emerging anionic contaminants and hybrid detection approaches (e.g., conductivity with mass spectrometry) will broaden analytical capabilities in environmental and industrial settings.

Conclusion

The unified ion chromatography approach meets EPA 300.1 and ISO 10304 standards in a single run, delivering robust performance across a wide concentration range. Automated eluent production and advanced suppression ensure reproducible, low-baseline operation, making this method a reliable, efficient, and sustainable solution for drinking water quality laboratories.

Reference

1. U.S. EPA Method 300.1 Determination of Inorganic Anions in Drinking Water by Ion Chromatography Revision 1.0, 1997
2. ISO 10304-1 Water Quality Determination of Dissolved Anions by Liquid Chromatography of Ions Part 1 Bromide, Chloride, Fluoride, Nitrate, Nitrite, Phosphate and Sulfate, 2007
3. ISO 10304-4 Water Quality Determination of Dissolved Anions by Liquid Chromatography of Ions Part 4 Determination of Chlorate, Chloride and Chlorite in Water, 2022
4. Boorman et al. Drinking Water Disinfection Byproducts Review and Approach to Toxicity Evaluation Environmental Health Perspectives 1999, 107, 207–217
5. Jackson PE Ion Chromatography in Environmental Analysis Encyclopedia of Analytical Chemistry Wiley 2000