Mutagenicity and Identification of the Reaction Products of Aqueous Chlorine or Chlorine Dioxide with L‐Tryptophan

Nonvolatile products generated from reactions of graded molar ratios of aqueous chlorine or chlorine dioxide with L‐tryptophan (1:1, 3:1 and 7:1) were shown to be direct‐acting mutagens to Salmonella typhimurium TA100 and TA98. Increasing the ratio of disinfectant relative to amino acid led to increased mutagenic activity, with mutagenicity highest at the 7:1 molar ratio. Several fluorescent bands obtained after thin layer chromatographic fractionation of the reaction mixtures were shown to be more mutagenic than the reaction mixtures. GC/MS analysis of the compounds in a highly mutagenic fraction of the aqueous chlorine reaction products identified 1,1,3‐trichloropro‐panonc, 1,1,3,3‐tetrachloropropanone and dichloroquinoline.