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The U.S. Environmental Protection Agency's (USEPA) Office of Ground Water andDrinking Water (OGWDW) collects national occurrence data on contaminants that are potentialcandidates for future regulation in drinking water, using Unregulated Contaminant MonitoringRegulations (UCMRs). The contaminants may be selected from the Contaminant Candidate List(CCL), or may be emerging contaminants with the potential for inclusion on future CCLs. Inorder for a contaminant to be included in the UCMR, a standardized analytical method for itsmeasurement in drinking water must be available. To be useful in collecting nationwideoccurrence data, the method must be rugged across a range of drinking water sources, sensitiveand highly specific to minimize false positives, and must also be cost effective and robustenough for use in commercial laboratory settings. A group of 11 emerging contaminants arebeing evaluated for inclusion in one or more drinking water methods for possible use in a futureUCMR. These methods will utilize solid phase extraction (SPE) for analyte concentration andgas chromatography/mass spectrometry (GC/MS) for identification and quantitation. Potentialcontaminants include acephate, captan, dimethipin, ethion, nitrofen, o-toluidine, oxyfluorfen,profenofos, quinoline, tebuconazole, and tribufos. Preliminary data have shown recoveries for 8of the 11 contaminants in the range of 70-130% when 1L samples were extracted at either acidicor neutral pH on various polymeric sorbents. Quinoline and o-toluidine were extractable only atneutral pH and were recovered at approximately 90% and 50%, respectively. Acephate wasrecovered at 8% or less on C-18 and on all polymeric sorbents evaluated. Separate 21-dayholding time studies were performed using the USEPA Method 527 sample preservation schemeat pH 3.8 and the USEPA Method 526 sample preservation scheme at neutral pH. o-Toluidine,quinoline, and dimethipin exhibited poor recoveries under acidic conditions on polystyrenedivinylbenzene (PSDVB) disks. Captan exhibited significant degradation over 21 days. Resultsfrom the neutral pH scheme were similar to pH 3.8 holding time results, but with quinolineexhibiting significant improvement in extraction efficiency and captan degrading at a faster rate. Includes 12 references, table, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 11File Size: 1 file , 820 KB