United States Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Research Abstract Government Performance Results Act (GPRA) Goal #2 Annual Performance Measure #202 Significant Research Findings: Method Development for the Determination of Alachlor ESA and Other Chloroacetanilide Degradates in Drinking Water Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. The substitution of the sulfonic acid or the carbonic acid for the chlorine atom greatly increases the water solubility of degradates relative to the parent compound and contributes to the increased potential for leaching into groundwater. As a result, alachlor ESA and other acetanilide degradation products were listed on the 1998 Safe Drinking Water Act Contaminant Candidate List (CCL). One acetamide and five acetanilde herbicides are currently registered for agricultural use in the U.S. The next step in the CCL-process is to collect data on the concentrations and occurrence of these compounds in the nation's drinking water supplies. However, the existing analytical methods for measuring chloroacetanilide degradates do not address issues specific to analyzing these compounds in drinking water. Because many of the methods were developed for ground water, dechlorination was not addressed nor was the method tested in all types of drinking water matrices. In addition, existing methods do not address all twelve ESA and OA degradates of the six U.S. registered acetanilide/acetamide herbicides. Therefore, the focus of this research was to develop a sensitive and specific analytical method for the analysis of alachlor ESA and other chloroacetanilide degradates in drinking water. The research goal was to develop a method for measuring alachlor ESA and eleven additional ESA and OA acetanilide degradates that are of interest to the environmental community. The method needed to be sensitive, selective and cost effective. The toxicological effect of these ESA and OA acetanilide degradates has not been extensively studied, thus no health effect level has been established. Therefore, a goal was established to achieve the lowest possible minimum reporting level (MRL) using cost- effective, but selective analytical methodology. The approach involved Scientific Problem and Policy Issues Research Approach ------- developing procedures for (1) sample collection, preservation, shipping and handling, (2) extraction and concentration of the target analytes from an aqueous solution, (3) separation of the analytes chromatographically, and (4) detection and quantitation. Solid phase extraction (SPE) techniques were investigated for the extraction of the acetanilide degradates. Because of the high water solubility of the ESA and OA degradates, graphitized carbon was the only solid phase sorbent capable of extracting all the twelve degradates from aqueous samples. Due to the ionic nature of these compounds, negative ion electrospray liquid chromatography/mass spectrometry (LC/MS) or tandem mass spectrometry (LC/MS/MS) were found to be the best choices for selective analytical methodology. The ultimate goal was to find an SPE procedure that, combined with LC/MS (or LC/MS/MS) analysis, produced a method that met data quality objectives of 70 tol30% mean recovery (% of true value) and less than 30% relative standard deviation (RSD). Results and The analytical method developed by NERL is sensitive, selective and cost Impact effective, and provides a well documented, standardized method, for the collection of nationwide occurrence data for alachlor ESA and other chloroacetanilide degradates, through EPA's Unregulated Contaminant Monitoring Regulation scheduled for proposal in 2005. If alachlor ESA or other chloroacetanilide degradates become regulated drinking water contaminants in the future, the method could also be used for compliance monitoring. The analytical method developed from this research can be used to measure alachlor ESA and eleven additional ESA and OA acetanilide degradates in drinking water samples. However, LC/MS could not be used to detect the target analytes due to co-extracted humic and/or fulvic material present in drinking water samples. The co-extracted material created a significant elevated LC/MS background which obscured the target peaks. Thus, it was necessary to detect and quantitate the ESA and OA degradates using LC/MS/MS. The MRLs achieved for the target analytes ranged from 0.016 to 0.11 |ig/L. Typical recoveries for the target analytes ranged from 80 to 108% and RSDs of less than 10% were obtained. As a result, this method will meet EPA's data quality objectives for the collection of nationwide occurrence data to support CCL regulatory determinations for ESA and OA acetanilide degradates. Publications resulting from this research: J. A. Shoemaker, "Novel Chromatographic Separation and Carbon Solid- Phase Extraction of Acetanilide Herbicide Degradation Products," J. AO AC Int., (2002), vol 85(6), 1331-1337. J.A. Shoemaker and M. Bassett, "Acetanilide Herbicide Degradation Products by LC/MS," Proceedings: American Water Works Water Quality Technology Conference, Philadelphi, PA, Nov. 2003. Research Collaboration and Research Products ------- J. A. Shoemaker, "Method Development for Alaclor ESA and Other Acetanilide Herbicide Degradation Products," 224th American Chemical Society National Meeting, Boston, MA, Aug. 2002. J.A. Shoemaker and M.V. Bassett, "U.S. EPA Method 535: "Measurement of Chloroacetanilide and Other Acetamide Herbicide Degradates in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)," National Exposure Research Laboratory, Microbiological and Chemical Exposure Assessment Research Division, Chemical Exposure Research Branch, 26 W. Martin Luther King Dr., Cincinnati, Ohio, 45268-1564. Future Research Due to the success of the method development, no further research is planned at this time. This method, designated Method 535, is available for use as the required analytical method in the Office of Ground Water and Drinking Water's upcoming proposal for the Unregulated Contaminant Monitoring Regulation. When finalized, this regulation will require a nationwide monitoring survey of selected CCL contaminants, including the ESAs and OAs of acetochlor, alachlor and metolachlor. Occurrence data from this survey will be used in the decision making process for the possible regulation of these acetanilide degradates. Questions and inquiries can be directed to: Dr. Jody A. Shoemaker USEPA National Exposure Research Laboratory 26 W. Martin Luther King Dr. Cincinnati, OH 45268-1564 Phone: (513) 569-7298 e-mail: shoemaker.iodv@epa.gov Funding for this project was through the U.S. EPA'S Office of Research and Development, National Exposure Research Laboratory, and the work was conducted by the Microbiological and Chemical Exposure Assessment Research Division. Contacts for Additional Information ------- |