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Application of an optimized total N-nitrosamine (TONO) assay to pools: placing N-nitrosodimethylamine (NDMA) determinations into perspective
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Kulshrestha, Pankaj, McKinstry, Katherine C., Fernandez, Bernadette O., Feelisch, Martin and Mitch, William A. (2010) Application of an optimized total N-nitrosamine (TONO) assay to pools: placing N-nitrosodimethylamine (NDMA) determinations into perspective. Environmental Science & Technology, Vol.44 (No.9). pp. 3369-3375. doi:10.1021/es100361f ISSN 0013-936X.
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Official URL: http://dx.doi.org/10.1021/es100361f
Abstract
Although N-nitrosodimethylamine (NDMA) has been the most prevalent N-nitrosamine detected in disinfected waters, it remains unclear whether NDMA is indeed the most significant N-nitrosamine or just one representative of a larger pool of N-nitrosamines. A widely used assay applied to quantify nitrite, S-nitrosothiols, and N-nitrosamines in biological samples involves their reduction to nitric oxide by acidic tri-iodide, followed by chemiluminescent detection of the evolved nitric oxide in the gas phase. We here describe an adaptation of this method for analyzing total N-nitrosamine (TONO) concentrations in disinfected pools. Optimal sensitivity for N-nitrosamines was obtained using a reduction solution containing 13.5 lit glacial acetic acid and 1 mL of an aqueous 540 g/L iodide and 114 g/L iodine solution held at 80 degrees C. The method detection limit for N-nitrosamines was 110 nM using 100 mu L sample injections and NDMA as a standard. N-nitrosamines featuring a range of polarities were converted to nitric oxide with 75-103% efficiency compared to NDMA. Evaluation of potential interfering species indicated that only nitrite and S-nitrosothiols were a concern, but both interferences were effectively eliminated using group-specific sample pretreatments previously employed for biological samples. To evaluate the low TONO concentrations anticipated for pools, 1 L samples were extracted by continuous liquid-liquid extraction with ethyl acetate for 24 h, and concentrated to 1 mL. N-nitrosamine recovery during extraction ranged from 37-75%, and there was a potential for artifactual nitrosation of amines during solvent reflux in the presence of significant nitrite concentrations, but not at the low nitrite concentrations prevalent in most pools. Using the 1000-fold concentration factor and 56% average extraction efficiency, the method detection limit would be 62 pM (5 ng/L as NDMA). The TONO assay was applied to six pools and their common tap water source in conjunction with analysis for specific nitrosamines. Even accounting for the range of N-nitrosamine extraction recoveries, NDMA accounted for an average of only 13% (range 3-46%) of the total nitrosamine pool.
Item Type: | Journal Article | ||||
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Subjects: | T Technology > TD Environmental technology. Sanitary engineering G Geography. Anthropology. Recreation > GE Environmental Sciences |
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Divisions: | Faculty of Science, Engineering and Medicine > Medicine > Warwick Medical School > Biomedical Sciences > Translational & Experimental Medicine > Metabolic and Vascular Health (- until July 2016) Faculty of Science, Engineering and Medicine > Medicine > Warwick Medical School |
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Journal or Publication Title: | Environmental Science & Technology | ||||
Publisher: | American Chemical Society | ||||
ISSN: | 0013-936X | ||||
Official Date: | 1 May 2010 | ||||
Dates: |
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Volume: | Vol.44 | ||||
Number: | No.9 | ||||
Number of Pages: | 7 | ||||
Page Range: | pp. 3369-3375 | ||||
DOI: | 10.1021/es100361f | ||||
Status: | Peer Reviewed | ||||
Publication Status: | Published | ||||
Access rights to Published version: | Restricted or Subscription Access | ||||
Funder: | Water Research Foundation (WaterRF) |
Data sourced from Thomson Reuters' Web of Knowledge
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