Disinfectants used in water treatment, including among others chlorine and bromine, can react with natural organic matter and anthropogenic contaminants in the water to form disinfection byproducts (DBPs).
Disinfection byproducts in natural waters
The occurrence of disinfection byproducts in natural waters poses a health risk for humans as well as aquatic organisms. This concerns not only the byproducts regulated by authorities, mainly the US Environmental Protection Agency, but also others that are not commonly monitored. This article presents a method for the fast, simultaneous determination of 15 regulated and unregulated disinfection byproducts, which was recently developed at the University of Arizona together with Metrohm and Agilent.
Disinfectants used in water treatment, including among others chlorine and bromine, can react with natural organic matter and anthropogenic contaminants in the water to form disinfection byproducts (DBPs). Among these are haloacetic acids (HAAs, see figure 1) such as dichloroacetic acid, which has been classified as possibly carcinogenic by the US Environmental Protection Agency (EPA) as well as the International Agency for Research on Cancer (IARC).
Ion chromatography–tandem mass spectrometry method
DBPs have been a subject of concern because of their adverse biological effects, not only on humans, but also on aquatic organisms. Coca Cola has had to recall 500 000 bottles of its Dasani water in the UK because it was contaminated with bromate, another DBP. Removing contaminants in drinking water while avoiding the formation of disinfection byproducts is a balancing act, the efficacy of which must be tested by monitoring DBP concentrations in water treated with disinfectants. A new ion chromatography–tandem mass spectrometry method enables the fast, simultaneous analysis of various DBPs in samples of disinfected water.
Health concerns associated with DBPs
The EPA stipulates limit values for several DBPs. These include bromate (BrO3−) and dalapon (2,2-dichloropropionate, DAL) as well as five HAAs, namely monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), monobromoacetic acid (MBAA), and dibromoacetic acid (DBAA), which are referred to as HAA5. In addition, four more HAAs have been commonly monitored in the past decade: tribromoacetic acid (TBAA), bromochloroacetic acid (BCAA), bromodichloroacetic acid (BDCAA), and chlorodibromoacetic acid (CDBAA). Together with the HAA5, these form the HAA9. EPA Method 557, which uses ion chromatography coupled to electrospray ionization tandem mass spectrometry (IC-ESI– MS/MS), is dedicated to the determination of these nine HAAs as well as bromate and dalapon in natural waters.
Recently, the iodinated counterparts of the above-listed HAAs caused public health concern because they appear to be even more toxic than the chlorinated and brominated HAAs. The substances in question are monoiodoacetic acids (MIAA), chloroiodoacetic acid (CIAA), bromoiodoacetic acid (BIAA), and diiodoacetic acid (DIAA). However, only few quantitative methods have been described that enable the simultaneous analysis of these four iodinated HAAs.
A new method: Determination of 15 DBPs
A new article recently published by Wu et al. in the Journal of Chromatography A describes a method that uses ion chromatography–tandem mass spectrometry (IC–MS/MS) to measure simultaneously the concentrations of all substances targeted by EPA Method 557 as well as the four iodinated substances listed above. Method detection limits for all analytes are at the sub-μg level and well below the respective maximum contaminant levels. Meanwhile, no sample preparation steps are necessary and, with 27 minutes measurement duration, the analysis takes just half as long as EPA Method 557.
