Method for measuring mutagen formation potential (MFP) on chlorination as a new water quality index

A novel water quality index, the mutagen formation potential (MFP) is proposed for use in evaluation of the quality of drinking water which may contain pollutants capable of forming mutagens when chlorinated under the conditions used in water purification processes. A method for measuring MFP was established as follows. The water sample to be tested is diluted until the TOC reaches 3–4 mg l −1, the pH is adjusted to 7.0±0.2, sodium hypochlorite is added to obtain conditions where Cl/TOC=3–4 mg Cl (mg C) −1, and the water sample is left standing for 24±2 h at room temperature. Thereafter, 2 l of the chlorinated water sample at pH 2.0±0.1 is passed through a Sep-Pak Plus CSP-800 cartridge to adsorb any mutagens formed, and DMSO is applied to the cartridge to desorb the mutagens. Then, a 2 ml sample of the eluate is collected after the DMSO had begun to flow out of the cartridge and evaluated by the Ames Salmonella mutagenicity assay (preincubation method).