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DEVELOPMENT OF A BETTER METHOD TO IDENTIFY AND MEASURE PERCHLORATE IN DRINKING WATER
Citation:
Hedrick, E J., D. J. Munch, AND T D. Behymer. DEVELOPMENT OF A BETTER METHOD TO IDENTIFY AND MEASURE PERCHLORATE IN DRINKING WATER. Presented at EPA Science Forum 2004, Washington, DC, June 1-3, 2004.
Impact/Purpose:
The goal of this project is to develop a method for the analysis of perchlorate in drinking water with a method detection limit between 0.02 and 0.1 ug/L (ppb) and a minimum reporting limit between 0.1 and 0.5 ug/L (ppb). [Note: this effort focuses on development of a sensitive and accurate method for laboratory analysis of perchlorate in drinking water: a related NERL task under the RARE program, 12505, focuses on development of a screening method for use with source waters.]
Description:
Perchlorate (ClO4 -) is an oxidant used primarily in solid propellant for rockets, missiles, pyrotechnics, as a component in air bag inflators, and in highway safety flares. Perchlorate tainted water has been found throughout the southwestern United States where its source has often been traced to defense industry activity or to manufactures who supply the defense industry. While there are other sources of perchlorate in drinking water, the connection of perchlorate to the defense industry has garnered increased media attention to the issue of perchlorate contamination. Perchlorate is a known thyroid hormone inhibitor; however, it was not until the mid-1990s that analytical methods were available for the detection of perchlorate in drinking water at levels of human health concern. As analytical methods have improved in sensitivity, the discovery of perchlorate in drinking waters at lower and lower concentrations has increased. Collaboration between EPA's Office of Research and Development, the Office of Water and an instrument manufacturer has produced a method that is capable of identifying concentrations of perchlorate in drinking water ten times lower than previous methods. The most distinguishing feature of this method, which is not available in existing methods, is the capability to identify perchlorate by its chlorine isotope ratio. This isotopic ratio, in addition to separation of perchlorate from interferences, virtually eliminates the likelihood of mistaken identity. Should perchlorate become regulated in drinking water, this method will enable definitive identification and quantitation of perchlorate at concentrations as low as 0.1 part per billion.