Separation of Mutagens from Drinking Water using Coupled Bioassay/Analytical Fractionation

Abstract

A general preparative procedure has been developed for the isolation of mutagenic components from organic residues of drinking water. This procedure features the Salmonella-microsome mutagenicity assay coupled with an analytical fractionation method which progressively focuses to the bioactive constituents of the complex mixture. The three-step method consists of: 1) semi-solid/liquid extraction; 2) radially compressed column octadecyl-silane reverse phase HPLC; 3) SEP-PAK^R concentration and solvent exchange of HPLC subfractions for chemical and biological characterization. Using as a model a carbon chloroform extracted organic residue mixture prepared from drinking water several years ago, three mutagenic HPLC subfractions were isolated, accounting for the bulk of the mutagenic activity of this complex mixture. Preliminary GC/MS results indicate the mutagenic activity is due to isomeric chlorinated aliphatic ethers. The biological characterization suggests the mutagenic specific activity of these compounds exceeds that of several known chemical carcinogens, e.g. β-naphthylamine. This data supports the model that drinking water contains a vast number of non-mutagenic compounds, possibly some of low activity, and may contain a small number of highly mutagenic compounds. We propose this coupled bioassay/chemical fractionation method for use in testing this model for organic residues of current environmental waters.