Gas chromatography/mass spectroscopy analysis of mutagenic extracts of aqueous chlorinated humic acid. A comparison of the byproducts to drinking water contaminants

Halogenated compounds other than trihalomethanes are formed during chlorination of drinking water and humic substances, but these compounds have been difficult to identify. Details are given of equipment and procedures developed for the isolation, identification, and quantification of mutagenic compounds in methylene-chloride and ether extracts of chlorinated humic acids that gave positive results in the Ames mutagenicity test. The procedures used included derivatization, solvent extraction, closed-loop stripping, and computer-associated column gas chromatography and mass spectroscopy. Details of the compounds identified, together with the method of isolation used and their mass spectra, are summarized in a table. The mutagenic compounds identified were similar to those found previously in chlorinated drinking water, suggesting that the reaction of chlorine with natural aquatic humic material might be the source of mutagens in drinking water. Some preliminary data are also included on the compounds produced by chlorination of humic acid in the presence of bromine.