Structural elucidation of disinfection by-products in treated drinking water

Two unusual disinfection by-products have been detected periodically in the gas chromatography/ mass spectrometry (GC/MS) characterization analyses of semi-volatile organics in treated drinking water. The electron ionization (EI) mass spectra contained mono-chlorinated and mono-brominated ions at m/ z 107/109 and 151/153, respectively. Library searching techniques suggested monohalogenated butanol structures but no matches could be found. Positive ion chemical ionization (CI) spectra contained mono-chlorinated and mono-b rominated ions at m/z 105/107 and 149/151, respectively. No [M + H](+) ions were initially observed. Accurate mass measurements confirmed the empirica l formulae for the significant ions in the EI spectra and the mono-halogena ted butanol structures. Further CI experiments with other reagent gases and instruments revealed possible molecular weights of 139 and 183 Da, respect ively. Tandem mass spectrometry (MS/MS) experiments in Fl and Cf were used to elucidate the fragmentation schemes. The two compounds have been tentati vely identified as 1-aminoxy-1-chlorobutan-2-ol and 1-aminoxy-1-bromobutan- 2-ol, respectively. Copyright (C) 2001 John Wiley & Sons, Ltd.