EPA 502.2 Analysis using the EA-600

Importance of the Topic

Determination of trace-level volatile organic compounds (VOCs) in drinking water is critical for public health and regulatory compliance. EPA method 502.2 targets 60 priority pollutants, many of which pose carcinogenic or toxic risks. Employing an optimized purge-and-trap GC-IR approach enhances sensitivity, selectivity, and reproducibility in environmental monitoring.

Objectives and Study Overview

This application note demonstrates the use of an EA-600 purge-and-trap GC-IR system to analyze EPA 502.2 VOCs in water. It evaluates chromatographic separation, peak shape, detector performance, and overall method robustness for simultaneous identification of 60 chlorinated, brominated, and aromatic compounds down to low ppb levels.

Methodology and Instrumentation

The analytical setup comprises:

• EA-600 environmental analyzer with integrated purge-and-trap unit
• Tremetrics photoionization detector (PID)
• HALL electrolytic conductivity detector (ELCO) in halogen mode
• GC module fitted with a 105 m × 0.53 mm RTX Volatiles capillary column

Key operating conditions:

• Sample: 5 mL water spiked at 20 ppb total VOCs
• Purge time: 11 min at 38 cc/min
• Trap temperature: 35 °C on Tenax–silica gel–charcoal
• Desorb: 280 °C for 2 min; bake: 220 °C for 4 min
• GC program: 25 °C hold 10 min, ramp 4 °C/min to 210 °C, hold 5 min

Key Results and Discussion

Baseline resolution was achieved for all 60 analytes, including closely eluting isomers (cis/trans-dichloroethene, xylenes). Peak shapes exhibited minimal tailing due to optimized trap material, water management, and column selection. The hyphenated GC-IR provided full-range FTIR spectra for compound confirmation, enhancing selectivity over single-detector setups.

Benefits and Practical Applications

This method enables:

• Simultaneous quantification and structural confirmation of chlorinated, brominated, and aromatic VOCs
• Lower detection limits (<1 ppb) with high reproducibility
• Compliance with EPA 502.2 requirements for regulatory reporting
• Reduced false positives through IR spectral matching

Future Trends and Potential Applications

Emerging developments may include integration of machine learning algorithms for automated spectral deconvolution, miniaturized purge-and-trap modules for field applications, and coupling with high-resolution mass spectrometry. Full FTIR databases and real-time monitoring capabilities will further streamline environmental analysis workflows.

Conclusion

The EA-600 GC-IR purge-and-trap system successfully separated and identified all 60 EPA 502.2 VOCs with excellent peak shapes and sensitivity. The combined PID, ELCO, and IR detection approach delivers robust, confirmatory analysis for drinking water quality assurance.

Reference

1. Washall T.P., Wampler J.W. Sources of error in purge and trap analysis of volatile organic compounds. American Lab. 22(18):38–44 (1990).
2. J.J. Keller & Associates. Air and Water Pollution: A Guide to Federal Regulations.