Determination of Perchlorate in Drinking Water Using a Microbore Reagent-Free Ion Chromatography System

Importance of Topic

Perchlorate is a persistent environmental contaminant derived from rocket fuels, fireworks, and industrial salts. It interferes with thyroid hormone production, posing risks to human health and development. Although no federal maximum contaminant level exists, some jurisdictions have set action limits (e.g., California’s 6 µg/L), highlighting the need for sensitive, accurate analytical methods.

Objectives and Study Overview

This study adapts U.S. EPA Method 314.0 for perchlorate determination in drinking water to a microbore (2 mm i.d.) ion chromatography format. The goal is to retain or improve method performance while reducing eluent consumption and waste generation compared to standard 4 mm columns.

Methodology and Applied Instrumentation

A Thermo Scientific Dionex ICS-2100 reagent-free ion chromatography system was employed with the following configuration:

• Column: Dionex IonPac AS16 analytical (2 × 250 mm) and AG16 guard (2 × 50 mm)
• Eluent: 65 mM KOH generated by EGC III cartridge at 0.22 mL/min
• Suppression: AERS 500 (2 mm) in external water mode coupled with CRD 200 device
• Temperatures: column at 30 °C, conductivity cell at 35 °C
• Injection: 250 µL push-full loop with 500 µL buffer wash
• Detection: suppressed conductivity (background < 1 µS, noise ~ 1–2 nS/min)

Main Results and Discussion

The calibration curve was linear from 1 to 50 µg/L perchlorate (r² = 0.999). The method detection limit in deionized water was 0.06 µg/L. Initial demonstration of capability at 25 µg/L yielded 96.3% recovery (RSD 0.54%). The matrix conductivity threshold (MCT) was established at 4520 µS/cm (600 mg/L mixed anions) with verification recovery of 80.6%. Drinking water samples fortified at 4 µg/L perchlorate returned recoveries between 87.8% and 99.8%, meeting EPA 314.0 criteria.

Benefits and Practical Applications

• Microbore format reduces eluent use and laboratory waste.
• Advanced suppressor lowers baseline noise and enhances sensitivity.
• Robust performance across diverse water matrices without extensive pretreatment.
• Fully compliant with U.S. EPA Method 314.0 requirements for accuracy, precision, detection limits, and matrix tolerance.

Future Trends and Potential Applications

Continued miniaturization of ion chromatography, integration of on-line sample cleanup (e.g., cartridge pretreatment), and coupling with mass spectrometric detection are promising directions. Further innovations in suppressor and eluent generation technology may yield even lower detection limits and reduced maintenance.

Conclusion

The 2 mm microbore ion chromatography approach fulfills U.S. EPA Method 314.0 performance criteria for perchlorate in drinking water while significantly reducing eluent consumption and waste generation. This setup offers a sensitive, precise, and resource-efficient solution for routine environmental monitoring and regulatory compliance.

References

1. Jackson, P.E.; Gokhale, G.T.; Streib, T.; Rohrer, J.S.; Pohl, C.A. J. Chromatogr. A 2000, 888, 151.
2. Gilbert, M.E.; Sui, L. Environ. Health Perspect. 2008, 116(6), 752.
3. California Department of Public Health. Perchlorate in Drinking Water, Effective October 2007.
4. Dionex Application Update 148: Determination of Perchlorate in Drinking Water using RFIC System. Thermo Scientific, 2015.
5. Dionex Application Update 145: Determination of Perchlorate in Drinking Water by Ion Chromatography. Thermo Scientific.
6. U.S. EPA Method 314.0: Determination of Perchlorate in Drinking Water by Ion Chromatography, 1998.