Improved Determination of Trace Concentrations of Perchlorate in Drinking Water Using Preconcentration with Two-Dimensional Ion Chromatography and Suppressed Conductivity Detection

Importance of the Topic

Perchlorate can impair thyroid function by blocking iodide uptake, leading to reduced hormone production and potential developmental defects. Recent studies show its presence in drinking water and food, raising concerns at trace levels. Advisory thresholds as low as 1 microgram per liter in water highlight the need for sensitive analysis methods.

Objectives and Study Overview

This study aims to improve the detection of sub-ppb perchlorate in environmental waters by combining preconcentration with two-dimensional ion chromatography and suppressed conductivity detection. The approach addresses limitations of existing EPA methods by enhancing sensitivity, selectivity, and robustness against high ionic strength matrices.

Used Instrumentation

• Thermo Scientific Dionex ICS-3000 Reagent-Free Ion Chromatography System with dual pump, eluent generator, detector module, and autosampler
• Dionex IonPac AS20 and AS16 analytical and guard columns in 4×250 mm and 2×250 mm formats
• Dionex EGC II KOH eluent cartridges and CR-ATC continuously regenerated anion trap columns
• Carbonate removal devices and ASRS ULTRA II suppressors in 2 mm and 4 mm formats for suppressed conductivity detection

Methodology

Samples are sterile filtered and injected at 4 mL onto the AS20 column in the first dimension. A valve switch at the perchlorate retention window diverts matrix ions to waste while trapping perchlorate on a TAC-ULP1 concentrator. The second dimension elutes trapped perchlorate on the AS16 column using isocratic KOH. Backpressure control and inline suppressor regeneration maintain stable baselines throughout the 45 minute run.

Main Results and Discussion

A quadratic calibration from 0.3 to 10 µg/L achieved r² of 0.9998 and a method detection limit of 0.016 µg/L. Fortified recoveries of 96–102 % at 0.5 µg/L and 99–101 % at 5 µg/L were obtained across reagent water, synthetic high inorganic water, and diverse drinking waters. Potential interferents observed in conventional methods were eliminated by the two-dimensional approach.

Benefits and Practical Applications

The two-dimensional method streamlines workflows by eliminating offline cartridge treatments and matrix spiking. It delivers sub-ppb sensitivity with high precision in complex matrices, making it suitable for regulatory compliance monitoring and environmental surveys.

Future Trends and Opportunities

Advances in inline preconcentration and automated valve control will further increase throughput. Integration with mass spectrometry could expand capabilities to multi-residue screening of emerging inorganic and organic contaminants. Enhanced data processing tools will support real-time decision making in water quality management.

Conclusion

The described two-dimensional ion chromatography method offers a robust, sensitive protocol for trace perchlorate analysis in water. By lowering detection limits and simplifying sample handling, it provides an effective tool for ensuring drinking water safety and supporting environmental monitoring.

Reference

• 1 Health Implications of Perchlorate Ingestion National Research Council National Academies Press 2005
• 2 Wagner Suarez Pepich Hautman J Chromatogr A 2004 1039 97
• 3 Haddow Klein Mitchell New England J Med 1999 341 2017
• 4 GAO 05-462 United States Government Accountability Office 2005
• 5 Yu Cañas Cobb Jackson Anderson Ecotoxicol Environ Saf 2004 58 44
• 6 Kirk Smith Tian Anderson Dasgupta Environ Sci Technol 2003 37 4979
• 7 California Department of Health Services Perchlorate in Drinking Water Overview 2006
• 8 State Perchlorate Advisory Levels EPA Federal Facilities Restoration and Reuse Office 2005
• 9 EPA Method 314.0 Determination of Perchlorate in Drinking Water Using Ion Chromatography 1999
• 10 Dionex Application Update 148 2005
• 11 EPA Method 314.1 Inline Column Concentration 2005
• 12 Dionex Application Note 176 In Press
• 13 Lin DeBorba Srinivasan Woodruff Pohl Anal Chim Acta 2006 567 135