Analysis of EDB, 123-TCP, and DBCP By USEPA Method 524.3

Analysis of EDB, 123-TCP, and DBCP by USEPA Method 524.3

Significance of the Topic

Monitoring trace levels of halogenated hydrocarbons in drinking water is essential for public health and regulatory compliance. Compounds such as 1,2-dibromoethane (EDB), 1,2,3-trichloropropane (123-TCP), and 1,2-dibromo-3-chloropropane (DBCP) are potential carcinogens and have strict maximum contaminant levels. Advances in analytical methodology can streamline laboratory workflows and improve detection capabilities.

Objectives and Study Overview

This study aimed to:

• Validate USEPA Method 524.3 for simultaneous analysis of EDB, 123-TCP, and DBCP in drinking water.
• Assess method performance in terms of sensitivity, precision, and accuracy across a calibration range of 20–2000 ppt.
• Compare reporting limits and workflow simplicity against traditional GC/ECD approaches (Methods 504.1 and 8011).

Applied Methodology and Instrumentation

Samples were preserved with ascorbic acid/maleic acid and analyzed without microextraction, using purge-and-trap concentration followed by GC/MS with SIM. Key instrumentation and parameters included:

• Eclipse 4760 Purge & Trap Concentrator with #10 Tenax®/silica gel trap.
• 4100 Autosampler with helium purge gas (45 mL/min), 10 min purge, 0.5 min desorb, 4 min bake cycles.
• Agilent 7890A GC with Restek Rtx-VMS 20 m × 0.18 mm column; split 30:1; oven ramp from 40 °C to 220 °C in two stages.
• Agilent 5975C MS in SIM mode (100 ms dwell); monitoring characteristic ions for analytes and deuterated/internal standards.

Main Results and Discussion

Calibration was linear between 20 and 2000 ppt with relative standard deviations below 5% for key analytes. Initial Demonstration of Capability at 100 ppt and 250 ppt showed recoveries within ±20% and RSDs under 5% for EDB, 123-TCP, and DBCP. Minimum reporting level confirmation at 20 ppt yielded mean recoveries within acceptance limits and prediction intervals meeting method criteria. Routine blanks and sparger rinses were necessary to mitigate preservative carryover.

Benefits and Practical Applications

The GC/MS SIM approach offers:

• Elimination of labor-intensive microextraction steps.
• Enhanced selectivity and lower background compared to ECD detection.
• Reporting limits at or below 4 ppt, meeting stringent regulatory needs.
• Streamlined workflow suitable for high-throughput drinking water testing laboratories.

Future Trends and Potential Applications

Outlook for analytical monitoring of halogenated compounds includes:

• Integration of automated inline cleanup and sample handling to further reduce manual intervention.
• Use of high-resolution mass spectrometry for broader compound screening and confirmation.
• Adaptation of purge-and-trap GC/MS methods for soil gas and remediation monitoring.
• Development of portable GC/MS platforms for on-site compliance testing.

Conclusion

USEPA Method 524.3 combined with purge-and-trap GC/MS SIM provides a rapid, sensitive, and accurate alternative to traditional GC/ECD methods for analysis of EDB, 123-TCP, and DBCP in drinking water. The simplified sample preparation and superior selectivity support routine regulatory monitoring and quality assurance.

Reference

• USEPA Method 524.3 Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry, Version 1.0, June 2009.
• USEPA Method 504.1 1,2-Dibromoethane (EDB), 1,2-Dibromo-3-chloropropane (DBCP), and 1,2,3-Trichloropropane in Water by Microextraction and Gas Chromatography, Revision 1.1, 1995.
• USEPA Method 8011 1,2-Dibromoethane and 1,2-Dibromo-3-Chloropropane by Microextraction and Gas Chromatography, Revision 0, July 1992.