US EPA 300 Method-Compliant Environmental and Water Analysis

Significance of the Topic

Accurate measurement of common inorganic anions such as fluoride, chloride, nitrite, nitrate, phosphate and sulfate is critical for ensuring environmental and drinking water safety. Regulatory frameworks like US EPA Methods 300.0 and 300.1 mandate strict performance criteria, driving the need for robust, sensitive, and reliable analytical methods.

Objectives and Study Overview

This study demonstrates the implementation of an EPA 300-compliant ion chromatography method using the Shimadzu HIC-ESP system. It aims to verify linearity, detection limits, repeatability, accuracy, and to apply the method to real water samples including bottled, water-severed and tap water.

Methodology and Instrumentation

Analyses were conducted using a suppressor-based ion chromatograph equipped with an electrodialytic suppressor.

• Column: Shim-pack IC-SA2 (250 mm × 4.0 mm I.D.)
• Mobile phase: 1.8 mmol/L sodium carbonate and 1.7 mmol/L sodium hydrogen carbonate
• Flow rate: 1.0 mL/min
• Column temperature: 40 °C
• Injection volume: 50 μL
• Detector: Conductivity detector with suppressor

Standard procedures from EPA Method 300 were followed for determining Method Detection Limits (MDL) using seven replicates and Student’s t-value at 99% confidence.

Main Results and Discussion

Linearity and Detection Limits

• Calibration ranges spanned 0.05–100 mg/L depending on analyte
• Correlation coefficients (r2) exceeded 0.9989 for all anions
• MDL values ranged from 1.49 μg/L (nitrite) to 14.38 μg/L (phosphate)

Repeatability and Accuracy

• Retention time RSD values remained below 0.30% over four days
• Peak area RSD values stayed under 1.0%
• Recovery rates for spiked ultrapure and tap water samples fell between 91.2% and 106%

Analysis of Real Samples

• Bottled water: low fluoride (0.08 mg/L) and nitrate (2.66 mg/L); detectable bromide and sulfate
• Water server: elevated chloride (~41 mg/L) and nitrate (8.93 mg/L)
• Tap water: similar profile to server water with phosphate undetected

Chromatograms showed clear separation of water dip peaks and early-eluting fluoride, confirming method robustness.

Benefits and Practical Applications

This approach provides high sensitivity, reproducibility, and regulatory compliance, making it ideal for routine environmental water monitoring, drinking water quality control, and regulatory reporting in laboratories and industrial QA/QC settings.

Future Trends and Potential Applications

Emerging developments may include advanced suppressor technologies, on-line automation, simultaneous analysis of additional anions and contaminants, and the deployment of compact field-portable IC systems for on-site water quality assessment.

Conclusion

The Shimadzu HIC-ESP ion chromatography system achieves EPA 300 compliance for quantitative analysis of seven inorganic anions with excellent linearity, low detection limits, high repeatability and accurate recoveries, supporting diverse routine and regulatory water analyses.