Determination of perchlorate in drinking water using ion chromatography

Significance of the Topic

Perchlorate contamination of drinking water poses a risk to thyroid function and developmental health, especially in fetuses and children. Regulatory agencies such as California have established strict public health goals and maximum contaminant levels. Sensitive and selective analytical methods are essential to monitor perchlorate at low μg/L concentrations and ensure water safety.

Objectives and Study Overview

The study aimed to develop a rapid, high-resolution ion chromatography method for quantifying perchlorate in drinking water. By employing a Thermo Scientific Dionex IonPac AS16-4 μm column, the method sought to improve sample throughput by 20%, reduce analysis time by three minutes per injection, and maintain or enhance detection sensitivity compared to existing EPA Method 314.0 and prior application updates.

Methodology and Instrumentation

The optimized method used a 2 mm Dionex IonPac AG16-4 μm guard column paired with a 2 × 250 mm Dionex IonPac AS16-4 μm analytical column. Key conditions included:

• Eluent: 65 mM KOH delivered by a Dionex EGC 500 cartridge with CR-ATC 500 trap column
• Flow rate: 0.38 mL/min; column temperature: 30 °C; injection volume: 250 μL
• Detection: suppressed conductivity via Dionex ADRS 600 suppressor (2 mm) in external water mode, 62 mA current
• Instrumentation: Thermo Scientific Dionex ICS-5000+ HPIC system with DP pump, DC detector, AS-AP autosampler, and Chromeleon CDS software

Reagents included degassed deionized water, sodium and potassium salts for calibration standards, and mixed common-anion solutions to evaluate sample matrix effects.

Main Results and Discussion

The method achieved baseline separation of perchlorate from common anions and 4-chlorobenzenesulfonate within 12 minutes. Calibration was linear from 1 to 50 μg/L (r2 = 0.9997). The limit of detection (LOD) based on S/N=3 was 0.073 μg/L; the method detection limit (MDL) from replicate injections was 0.062 μg/L—over three times lower than previously reported. Matrix interference studies with high chloride, sulfate, and carbonate concentrations confirmed stable perchlorate response. Analysis of three tap water samples detected perchlorate at 0.84 μg/L in one sample, with recoveries of 98.8–104% upon spiking.

Benefits and Practical Applications

The high-resolution AS16-4 μm column enables faster run times without sacrificing selectivity or sensitivity. The reagent-free IC system simplifies maintenance and enhances reproducibility, making the method well suited for routine monitoring of perchlorate in municipal water supplies and environmental laboratories.

Future Trends and Potential Applications

Advances in column technology and suppressor design are expected to further reduce analysis time and improve detection limits. Coupling ion chromatography with mass spectrometry could expand multi-contaminant screening capabilities. Automation of sample preparation and data processing will increase throughput for large-scale monitoring programs.

Conclusion

The developed method delivers rapid, sensitive, and robust determination of perchlorate in drinking water using a Dionex IonPac AS16-4 μm column and reagent-free IC system. It meets regulatory requirements and offers significant improvements over legacy EPA methods in speed and detection limits.

Reference

1. Jackson PE et al. J. Chromatogr. A 2000, 888, 151.
2. California Water Boards. Perchlorate in Drinking Water, accessed 2019.
3. U.S. EPA Method 314.0; EPA, Cincinnati, OH, 1997.
4. Thermo Scientific Application Update 148: Determination of perchlorate in drinking water using reagent-free IC.
5. Thermo Scientific Dionex IonPac AS16-4 μm column manual.