IDENTIFICATION OF BROMOHYDRINS IN OZONATED WATERS

Because ozonation is becoming a popular alternative to chlorination fo r disinfection of drinking water and little is known about the potenti al adverse health effects of ozonation disinfection by-products (DBPs) , we have sought to identify ozone DBPs, particularly brominated organ ics, which are of principal concern due to their anticipated toxicity. Using gas chromatography coupled (independently) to low-resolution el ectron-impact mass spectrometry (LR-EI-MS), high-resolution EI-MS, che mical ionization MS (with 2% ammonia in methane), and Fourier transfor m infrared spectrometry, we have identified a series of bromohydrins a nd related compounds detected in extracts of an ozonated natural water sample that was artificially enhanced with bromide. The bromohydrins, which constituted the majority of by-products in the samples we studi ed, were detected but could not be identified by GC/LR-EI-MS, the tech nique used almost exclusively for environmental monitoring. A key to i dentifying the bromohydrins was the manifestation of intramolecular hy drogen bonding in the gas-phase IR spectra. Many of the by-products ha d two chiral centers, and both diastereomers were present and were sep arated by GC. In most cases, the IR spectra also permitted us to disti nguish between diastereomers. We interpreted the IR and EI-MS spectra of several representative compounds in detail, and gave peak assignmen ts for all that were identified. Molecular mechanics calculations and an experimental determination of the enthalpy change for conversion of free and hydrogen-bound conformers for a representative bromohydrin w ere used to verify the IR interpretations.