Validation of EPA Method 524.3 for Low Level Analysis of TCP, EDB, and DBCP

Topics in Drinking Water
Oral Presentation

Prepared by Y. Li, B. Davis
Eurofins Eaton Analytical, LLC, 110 South Hill Street, South Bend, Indiana, 46617, United States

Contact Information:; 574-472-5562


1,2,3-Trichloropropane (TCP) has been widely used as an industrial solvent, a cleaning and degreasing agent, a chemical intermediate in the production of other chemicals, and a crosslinking agent in the production of polysulfides. TCP is also associated with pesticide products such as soil fumigants. The U.S. Environmental Protection Agency (EPA) has classified TCP as “likely to be carcinogenic to humans”. Human exposure to TCP is most likely to occur near hazardous waste sites where TCP is improperly stored or disposed, or at locations that manufacture or use the chemical. However, TCP can contaminate drinking water sources and has been detected in groundwater and finished drinking water. In the Third Unregulated Contaminant Monitoring Rule (UCMR 3) of 2013-2015, 36.848 drinking water samples were analyzed from 4,916 participating public water systems (PWSs), 256 results (0.7%) and 67 PWSs (1.4%) were detected at ≥ the set minimum reporting level (MRL) of 0.03 µg/L.

Currently, there is no federal maximum contaminant level (MCL) set for TCP. In 2012, U.S. EPA established a 10-day health advisory (HA) of 0.6 mg/L for TCP in drinking water for a 10 kg child, and drinking water equivalent level (DWEL) for TCP is 0.1 mg/L. However, various states have established more restrictive human health-based drinking water guidance values or regulations. New Jersey Department of Environment Protection (NJDEP) recently established an MCL of 0.03 µg/L (September 4, 2018). California State Water Resources Control Board (SWRCB) established an MCL of 0.005 µg/L and a Detection Limit (DL) for Purposes of Reporting (DLR) of 0.005 µg/L (December 14, 2017), and Office of Environmental Health Hazard Assessment (OEHHA) established a Public Health Goal (PHG) of 0.0007 µg/L and Notification Level of 0.005 µg/L (2009). The State of Hawaii established a state MCL of 0.6 µg/L (2009). In addition, the Minnesota Department of Health established a human health-based drinking water guidance value of 0.003 µg/L.

TCP can be analyzed by using gas chromatography (GC) coupled with electron-capture detection (ECD) or mass spectrometry (MS). TCP can be analyzed by itself or together with other chemicals, including regulated 1,2-dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) also known as 1,2-dibromoethane. Both DBCP and EDB are potent human carcinogens and mutagens and are included in the national primary drinking water regulations. The MCLs are 0.2 µg/L for DBCP . and 0.05 µg/L for EDB, respectively. GC/ECD combined with microscale liquid-liquid extraction (MLLE) used to extract and enrich samples, such as EPA Methods 504.1 and 551.1, is capable of providing MRLs of approximately 0.02 µg/L for TCP and approximately 0.01 µg/L for EDB and DBCP, respectively. To comply with CA’s MCL of TCP, more sensitive SRL 524M-TCP developed by California Department of Health Services (2002) must be used. SRL 524M-TCP is a modified EPA Method 524.2 and uses a selected ion monitoring (SIM) mode to achieve better sensitivity.

In this work, we will present EPA Method 524.3 as a good alternative for the simultaneous compliance analysis of TCP, DBCP, and EDB. The validation has confirmed that EPA Method 524.3 with SIM can provide an MRL of 0.005 µg/L for all the three analytes. The obtained MDLS are 0.0014 µg/L for TCP, 0.0016 µg/L for DBCP, and 0.0010 µg/L for EDB, respectively. Compared with the SRL 524M-TCP method, EPA Method 524.3 also demonstrates more restrictive quality control requirements. Our work also demonstrates that the simultaneous analysis of TCP, DBCP, and EDB is more cost-effective for compliance with drinking water regulations. It is our expectation that this presentation will provide important laboratory experience and experimental data to support new TCP regulations.