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This paper presents the results of a survey of N-nitrosodimethylamine (NDMA)occurrence in treated waters of 21 North American drinking water treatment plants.Quarterly samples of treatment plant influent, finished, and distribution system waterswere collected and analyzed for NDMA as part of an American Water Works AssociationResearch Foundation and Water Environment Research Foundation jointly funded study.Sampled systems were located in seven states of the United States and four provincesof Canada and comprised systems with pristine sources as well as systems downstreamof wastewater treatment plants. Various treatment processes and disinfectants were representedas were various detention times and pipe materials in the distribution system.Four quarters of samples were analyzed for most of the systems. Information on sourcewater characterization, treatment processes, and treated water distribution systemparameters was also collected for many systems.Most NDMA analyses were performed by solid-phase extraction with a carbonresin (Ambersorb 572; SUPELCO, Bellefonte, Pa.) and gas chromatography (GC)/high-resolutionmass spectrometry (HRMS). The samples all had NDMA values below 7 ng/Lexcept for two systems, which had NDMA values above 10 ng/L. An NDMA levelabove the method reporting limit (MRL), from 0.6 to 1 ng/L, was detected in only one of81 plant influent water samples. Values for NDMA in 81 plant effluent samples rangedfrom below the MRL to 30 ng/L and in 95 treated water distribution samples from belowthe MRL to 24 ng/L. Matrix spike recoveries ranged from 80 to 120 percent, with anaverage of 94 percent. In addition, 12 samples were analyzed by a reference laboratory,with comparable results. The relative differences in replicate analyses ranged from zeroto 16 percent, with an average difference of 6 percent. The relationship of NDMA levelswith other parameters (e.g., source water, treatment processes, disinfectants, detentiontime) is being evaluated to gain insight on formation and degradation of NDMA. Includes 6 references, tables, figures.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 19File Size: 1 file , 380 KB