AWWA WQTC59001

Chloral hydrate (CH), a chlorinated acetaldehyde, has been found in chlorinated drinking water. In addition, other related haloacetaldehydes (HAs), have been tentatively identified in drinking water samples. However, authentic standards required for quantification of these HAs have only recently been available commercially. Dichloroacetaldehyde (DCA), bromochloroacetaldehyde (BCA), dibromoacetaldehyde (DBA), bromodichloroacetaldehyde (BDCA), chlorodibromoacetaldehyde (CDBA), and tribomoacetaldehyde (TBA) were purchased and verified for purity and stability using a dual-column GC-ECD system. Several commercial standards contained other target HAs. The stability of the HAs stock solutions was solvent dependent. When prepared in acetone, several HAs, particularly the brominated species partially degraded and bromoacetone was formed. However, the target HAs were all stable in methyl-tert-butyl-ether (MTBE)+ for up to 8 months. The analytical parameters, required for the quantification of HAs in water, were determined and used to evaluate the stability of the HAs in water. All the target HAs were stable in water for up to 14 days using consolidated method sampling protocol conditions (field pH adjustment [pH 4.2] and storage at 4C). However, at typical drinking water pH and temperature conditions, the stability varied with the HA species, pH, temperature and storage period. The trihalogenated acetaldehydes degraded, in part, to their corresponding trihalomethanes (THMs) at increasing pH and temperature. Most target HAs were detected in Canadian drinking water samples and the speciation was dependent on water quality (e.g. bromide concentration) and treatment processes. Also, the pattern for the di- and tri- halogenated species varied within the distribution system. For selected water samples, the contribution of CH to the total HAs ranged from 7% to 51% and the total HAs represented 10% to 46% of the total THMs. Includes 19 references, tables, figures.