GC-MS determination of volatile organic compounds in drinking water supplies in Mexico

Water samples from municipal sources and specific sites in the distribution systems in five Mexican cities were analyzed for 40 volatile organic compounds using a gas chromatograph-mass spectrometer system coupled with a purge-and-trap sampler. Benzene and four halogenated compounds, methylene chloride, chloroform, dibromomethane, and dibromochloromethane, were consistently detected in all five cities. Another 20 analytes were identified in some of the 48 sites involved. In many cases, detected concentrations were higher than some internationally accepted drinking water standards. At the time of the study. Mexican regulations did not include values for maximum allowable concentrations levels for volatile organic compounds. From 1996, total trihalomethanes and 10 organochlorine pesticides have been included in Mexican drinking water regulations. (C) 2000 by John Wiley & Sons, Inc.