Impact/Purpose:

To develop sample pretreatment and/or preconcentration modifications to EPA Method 314.0 in order to achieve lower method detection limits in drinking waters containing high total dissolved solids.

Description:

Through the Regional Applied Research Effort (RARE) program, the Chemical Exposure Research Branch and Region 9 personnel in San Francisco, California are collaborating on a project to explore sample pretreatment and preconcentration techniques to lower the method detection limits of EPA Method 314.0 "Determination of Perchlorate in Drinking Water Using Ion Chromatography" for drinking water. Region 9 personnel have identified this project as a high priority issue that will support policy and regulatory issues in Region 9. The proposed research addresses a persistent groundwater contaminant that originates primarily from releases from the manufacture or testing of solid rocket fuel for the military or NASA. Perchlorate is highly soluble and extremely mobile in the environment. As a result of new health effects data, the California Department of Health Services has adopted an new action level of 4 ppb, lower than the interim level of 18 ppb issued in 2001.

The currently approved method for low level perchlorate analyses is Method 314.0, which uses a high performance liquid chromatographic pump and an anion exchange column for separation of the perchlorate anion (ClO4 -) from other ions in solution with detection by suppressed conductivity. The MDL of the method is 0.53 ppb and the minimum reporting level is 4 ppb. The primary human health effect of perchlorate is inhibition of iodide uptake by the thyroid gland. By disrupting thyroid hormone production, perchlorate interferes with metabolism and can affect brain development in fetuses and children, leading to mental impairment. Although toxicological studies are still in progress, recent feeding studies on pregnant female rats showed changes in developmental brain morphology of the developing fetuses at the lowest dose tested. These results indicated that the concentration level of concern for perchlorate in drinking water may be less than 1 ppb, a concentration that is an order of magnitude below the original estimate of 18 ppb and below the minimum reporting level (4 ppb) of EPA Method 314.0. For environmental laboratories with modest capabilities, ion chromatography with conductivity detection is currently the most sensitive, affordable and easily implemented technique for perchlorate analysis. Thus, it is the goal of this task to modify this technique to achieve lower perchlorate detection limits by simple modifications in sample pretreatment and preconcentration. Although not known at this time, such modifications may be sufficient in the event that perchlorate is regulated or undergoes a second occurrence survey in 2004.

Record Details:

Record Type:PROJECT

Start Date:10/01/2002

Projected Completion Date:05/01/2005

Record ID: 56081

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Project Information:

Progress :The Chemical Exposure Research Branch (CERB) continues to provide technical assistance to Region 9 on perchlorate methodology while the method modification is being conducted via contract. The most appropriate vehicle identified to complete this work was an experienced contractor with the Office of Ground Water and Drinking Water (OGWDW), Technical Support Center (TSC) in Cincinnati, Ohio. The project has been funded, a work assignment is in place, and CERB is providing technical oversight and advice. The Project Officer and Work Assignment Manager for the task is David Munch (OGWDW, TSC). There have been significant delays in completing this task; however, the extensions have not required additional funding. It is anticipated that the project will be completed by May 2005.

Relevance :Perchlorate is an analyte on the U.S. EPA's Candidate Contaminant List. The Safe Drinking Water Act (SDWA), as amended in 1996, requires the U.S. EPA to establish criteria for programs to monitor unregulated contaminants and to publish a list of unregulated contaminants. The U.S. EPA has listed perchlorate on the Unregulated Contaminant Monitoring Rule (UCMR) list and data is currently being collected on its occurrence in U.S. drinking water.

U.S. EPA Region 9 personnel desire a method for low-level determination of perchlorate in drinking water and source waters. The outcome of this task will be to explore modifications to the currently approved method for perchlorate determination to ensure clean safe drinking water in areas susceptible to perchlorate contamination.

Clients :U.S. EPA Region 9, Bobbeye Smith

Project IDs:

ID Code :12505

Project type :OMIS