Trihalomethanes drinking water

The Analysis of Trihalomethanes in Drinking Water by Liquid Extraction US Environmental Protection Agency, Environmental Monitoring and Support Laboratory, Cincinnati, OH, 9 Sept. 1977. 

Although each gas chromatographic method has its own unique considerations, the following description of the determination of trihalomethanes in drinking water provides an instructive example of a typical procedure. 

Method f2.i describes the analysis of the trihalomethanes CHCI3, CHBr3, CHChBr, and CHClBr2 in drinking water using a packed column with a nonpolar stationary phase. Predict the order in which these four trihalomethanes will elute. 

The analysis of trihalomethanes in drinking water is described in Method f2.i. A single standard gives the following results when carried through the described procedure. 

Trihalomethanes. Wherever chlorine is used as a disinfectant in drinking-water treatment, trihalomethanes (THMs) generaUy are present in the finished water. The THMs usuaUy formed are trichloromethane (chloroform), bromodichloromethane, dibromochloromethane, and tribromomethane (bromoform). There are four main techniques for the analysis of THMs headspace, Hquid— Hquid extraction (Ue), adsorption—elution (purge—trap), and direct aqueous injection. The final step in each technique involves separation by gas—Hquid chromatography with a 2 mm ID coUed glass column containing 10 wt % squalene on chromosorb-W-AW (149—177 p.m (80—100 mesh)) with detection generaUy by electron capture. 

Trihalomethanes in Drinking Water (Sampling Analysis, Monitoring and Compliance), U.S. Envkonmental Piotection Agency, EPA/570/9-83-002, Washington, D.C., 1983. 

Total Trihalomethanes none 0.10 Liver, kidney or central nervous Byproduct of drinking water disinfection... 

Under drinking water plant treatment conditions, humic materials and/ or resorcinol do not produce trihalomethanes with chlorine dioxide even when a slight excess of chlorine (1 percent to 2 percent) is present. Also, saturated aliphatic compounds are not reactive with chlorine dioxide. Alcohols are oxidized to the corresponding acids. 

Although reactions carried out by ozone have attracted enormous attention in the atmospheric environment, ozone has also been used extensively in the treatment of drinking water without the production of undesirable trihalomethanes from the use of molecular chlorine (Richardson et al. 1999). It has been examined for the removal of a number of contaminants, and ozone is considered to be a selective oxidant, even though quite complex reactions may occur. 

Chlorine dioxide has been used widely in Europe since the early 1940 s as a drinking water disinfectant. More recently the USA has suggested the use of chlorine dioxide to reduce the formation of chloro-organic compounds particularly chloroform and other trihalomethanes (THM s) which are known carcinogens(7). 

We mentioned in Chapter 2 (Section 2.6.1) that a purge-and-trap procedure sometimes precedes an analysis by gas chromatography. An example of this procedure is found in the City of Lincoln, Nebraska, Water Treatment Plant Laboratory. Water treatment includes chlorination. When water is chlorinated, chlorine reacts with organic matter to form trihalomethanes (THMs), such as chloroform, bromoform, bromodichloromethane, and chlorod-ibromomethane. THMs in water are regulated by the Safe Drinking Water Act, and so the laboratory must analyze the treated water to determine their concentration. 

The EPA sets rules for the amount of chloroform allowed in water. The EPA limit for total trihalomethanes, a class of chemicals that includes chloroform, in drinking water is 100 micrograms per liter (pg/L, 1 pg/L = 1 ppb in water). Furthermore, EPA requires that spills of 10 pounds or more of chloroform into the environment be reported to the National Response Center. 

Balster RL, Borzelleca JF. 1982. Behavioral toxicity of trihalomethane contaminants of drinking water in mice. Environ Health Perspect 46 127-136. 

Cech I, Smith V, Henry J. 1982. Spatial and seasonal variations in concentration of trihalomethanes in drinking water. In Albaiges J, ed. Analytical techniques in environmental chemistry, II. New York, NY Pergamon Press, 19-38. 

Furlong EAN, Dltri FM. 1986. Trihalomethane levels in chlorinated Michigan drinking water. Ecological Modelling 32 215-225. 

Kasso WV, Wells MR. 1981. A survey of trihalomethanes in the drinking water system of Murfreesboro, Tennessee, USA. Bull Environ Contam Toxicol 27 295-302. 

Drinking water standard (final) MCLG zero MCL 0.08 mg/L. Total for all trihalomethanes... 

Analysis of Trihalomethanes in Drinking Water by the Purge and Trap Method... 

Waller K, Swan SH, DeLorenze G, Hopkins B (1998) Trihalomethanes in drinking water and spontaneous abortion. Epidemiology 9 134—140... 

U.S. Environmental Protection Agency (1979) National interim primary drinking water regulations control of trihalomethanes in drinking water Final rules. Fed Regist 44 68624-68705... 

Thomas RF, Weisner MJ, Brass HJ (1980) The fifth trihalomethane dichloroiodomethane. Its stability and occurrence in chlorinated drinking water. In Jolley RL, Brungs WA, Gumming RB, Jacobs VA (eds) Water chlorination environmental impact and health effects, vol 3. Ann Arbor Science, Ann Arbor, MI, pp 161-168... 

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