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During chloramination of bromide-containing waters, the main brominated amine formed is bromochloramine (NHBrCl). To date, there is no analytical method, free of interference, allowing its accurate quantification. The major reason is that it is not possible to produce a pure NHBrCl solution. In this study, we report a method allowing the accurate quantification of NHBrCl with membrane introduction mass spectrometry (MIMS). First, the molar absorption coefficient for NHBrCl was determined by quantifying NHBrCl as 2,4,6-tribromophenol by HPLC-UV and comparing the results with the direct UV response at 320 nm. A molar absorption coefficient of 304 Mcm was obtained. The results obtained by direct UV measurements were compared to the MIMS signal recorded at m/ z 131 corresponding to the mass of the molecular ion and used to establish a calibration curve. A limit of detection of 2.9 μM (378 μg/L) was determined. MIMS is the only method enabling the unambiguous quantification of NHBrCl, as it is based on m/ z 131, while with other analytical techniques, other halamines can interfere, i.e., overlapping peaks with direct UV measurements and reaction of several halamines with colorimetric reagents or phenols. While the detection limit is not quite low enough to measure NHBrCl in actual drinking water, this analytical method will benefit the scientific community by allowing further mechanistic studies on the contribution of NHBrCl to the formation of toxic disinfection by-products.

No abstract

ABSTRACf: Fermented organic wastes were investigated as electron donors for denitrification in activated sludge. Fermentation of primary domestic wastewater sludge improved denitrification rates in nonacclimated activated sludge, whereas fermentation of wastewater had no effect. In both acclimated and nonacclimated activated sludges, higher denitrification rates were obtained with fermented sludges (from domestic wastewater or swine waste) than with either methanol or acetate. Methanol was equivalent to acetate as electron donor for denitrification in acclimated sludges but supported lower denitrification rates than acetate in nonacclimated sludges. Mixing and pH were important determinants 'ofvolatile fatty acid yields from organic wastes, whereas temperature in the range of 28°C to 35°C had little influence. Waler Environ. Res .. 67, 1119(1995).