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IDENTIFICATION OF NEW BROMINATED ACIDS IN DRINKING WATER
Citation:
Richardson, S D., A D. Thruston Jr., B. McKague, C. RavAcha, AND V. Glezer. IDENTIFICATION OF NEW BROMINATED ACIDS IN DRINKING WATER. Presented at 50th American Society for Mass Spectrometry Conference, Orlando, FL, June 2-6, 2002.
Impact/Purpose:
Determine the actual concentrations of suspected health-impacting DBPs produced using non-chlorine disinfectants, how often they occur, under what conditions they are formed, and their fate and transport in the distribution system.
Description:
Since chloroform was identified as the first disinfection by-product (DBP) in drinking water, there has been more than 25 years of research on DBPs. Despite these efforts, more than 50% of the total organic halide (TOX) formed in chlorinated drinking water remains unknown. There is even less known about the identity of DBPs formed by alternative disinfectants, such as ozone, chlorine dioxide, and chloramine. The understanding of DBPs is important because epidemiologic studies have indicated a potential risk of cancer and reproductive/developmental effects resulting from the consumption of disinfected tap water. Recent epidemiologic and toxicologic studies have also indicated that the bromine-containing DBPs may be more toxicologically important than the chlorinated analogs. In this study, we report the identification of new, potentially toxicologically significant, brominated acids that were not previously known.These new brominated acids were identified using GC/MS. High resolution electron ionization mass spectrometry was used to confirm potential empirical formulas suggested through the interpretation of the mass spectra. Drinking water samples were treated with pre-chlorination followed by chlorine dioxide-chloramine treatment, and were collected from a major drinking water treatment plant in Israel, whose source water contains extremely high levels of bromide. It is the presence of this natural bromide that allows the formation of bromine-containing DBPs. Drinking water samples were acidified and extracted with XAD resins (8 over 2). The resins were eluted with ethyl acetate, and the resulting extracts were rotoevaporated to 1 mL and methylated using BF3/methanol.
The bromine-containing acids were identified as the derivatized methyl esters. A few of these compounds were present in the spectral library databases (NIST and Wiley), but many were not. Therefore, fragmentation patterns in their mass spectra had to be interpreted and tentative identifications assigned. High resolution MS was used to confirm empirical formula assignments for the molecular ions and the fragments. In addition to the commonly observed brominated acetic acids, interesting new bromo-acids were identified, including brominated propanoic acids, propenoic acids, butanoic acids, butenoic acids, and dioic acids. The following compounds were confirmed through the analysis of standards (most of which were prepared synthetically): 2-bromobutanoic acid; 4-bromobutanoic acid; 3,3-dibromopropenoic acid; 2,3-dibromopropenoic acid; 2,3-dibromobutenoic acid, tribromopropenoic acid; threo-2,3-dibromobutanedioic acid; and trans-dibromobutendioic acid.