Development of a U.S. EPA Drinking Water Method for the Analysis of Emerging Organic Contaminants by GC/MS

摘要

The United States Environmental Protection Agency's (USEPA) Office of Ground Water and Drinking Water (OGWDW) collects national occurrence data on contaminants that are potential candidates for future regulation in drinking water, using Unregulated Contaminant Monitoring Regulations (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. In order for a contaminant to be included in the UCMR, a standardized analytical method for its measurement in drinking water must be available. To be useful in collecting nationwide occurrence data, the method must be rugged across a range of drinking water sources, sensitive and highly specific to minimize false positives, and must also be cost effective and robust enough for use in commercial laboratory settings. A group of 11 emerging contaminants are being evaluated for inclusion in one or more drinking water methods for possible use in a future UCMR. These methods will utilize solid phase extraction (SPE) for analyte concentration and gas chromatography/mass spectrometry (GC/MS) for identification and quantitation. Potential contaminants include acephate, captan, dimethipin, ethion, nitrofen, o-toluidine, oxyfluorfen, profenofos, quinoline, tebuconazole, and tribufos. Preliminary data have shown recoveries for 8 of the 11 contaminants in the range of 70-130% when 1L samples were extracted at either acidic or neutral pH on various polymeric sorbents. Quinoline and o-toluidine were extractable only at neutral pH and were recovered at approximately 90% and 50%, respectively. Acephate was recovered at 8% or less on C-18 and on all polymeric sorbents evaluated. Separate 21-day holding time studies were performed using the USEPA Method 527 sample preservation scheme at 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 polystyrene divinylbenzene (PSDVB) disks. Captan exhibited significant degradation over 21 days. Results from the neutral pH scheme were similar to pH 3.8 holding time results, but with quinoline exhibiting significant improvement in extraction efficiency and captan degrading at a faster rate.