USEPA Method 551 uses ammonium chloride with pH adjustment for the preservation of a range of volatile disinfection byproducts (DBPs) in chlorinated drinking water samples. However, the use of ascorbic acid as a preservative has been recommended for the analysis of chloral hydrate and cyanogen chloride. A method, adapted from USEPA Method 551, was used in recent Health Canada studies for the analysis of target DBPs. The method was based on methyl t-butylether (MTBE) extraction of water samples containing ammonium chloride preservative and adjusted to pH 4.5 in the field. To determine cyanogen chloride, the method was modified by substituting the ammonium chloride with ascorbic acid solution according to Sclimenti et al. These two methodologies were compared for Method 551 target DBPs in a survey of 17 water treatment facilities using chlorination, chloramination and ozonation. This paper presents comparative data for brominated DBPs and other minor DBPs. It has been suggested that, in some waters, ascorbic acid may not be a suitable preservative for some brominated and bromo-chloro-DBPs, particularly the brominated acetonitriles. Therefore, additional studies were undertaken to evaluate the stability of brominated DBP species in the presence of ascorbic acid. These data are also presented and discussed.