| Abstrakt: |
Mechanism of Chloroform Formation by Chlorine and Its Inhibition by Chlorine Dioxide. SUH, D. H., and ABDEL-RAHMAN, M. S. (1985). . 5, 305–313. Chlorination of drinking waters leads to the formation of trihalomethanes arising from the reaction of chlorine and organic substances. Therefore, chlorine dioxide (ClO) which does not produce trihalomethanes is being considered as an alternative disinfectant. It has been reported that rat blood chloroform levels were significantly decreased after treatment with ClO. Studies were conducted to investigate the mechanisms of chloroform formation by chlorine (HOCl) and its inhibition by ClO (5 mg/liter) in the presence of HOCl (5, 10, 20 mg/liter) using sodium citrate (1 mM) as an organic substance. When citrate was reacted with HOCl, β-ketoglutaric acid, monochloroacetone, dichloroacetone, and trichloroacetone were produced as reaction intermediates and chloroform as a final product. There was a linear relationship between the concentrations of HOCl and the formation of chloroform. When ClO was substituted for HOCl, neither chloroform was formed nor citrate concentration was changed. Further, chloroform formation was inhibited by ClO in the presence of HOCl and citrate and the degree of inhibition depends on the ratio of ClO7sol;HOCl. Gas chromatograph/mass spectrometer analysis indicates that this inhibition is related to the reaction of ClO with β-ketoglutaric acid to form malonic acid. Chlorine dioxide also oxidizes other intermediates such as monochloroacetone and dichloroacetone to acetic acid. These studies indicate that ClO inhibits chloroform formation from citrate and HOCl by the oxidation of the intermediates which were involved in the reaction of chloroform formation. [ABSTRACT FROM PUBLISHER] |
