Looking at the shelves in the beverage aisle of my grocery store, the number of choices for bottled water is mind-boggling! It’s evidence that bottled water has been one of the fastest growing beverage markets over the last few decades. Being in the food and beverage industry (link to food and beverage community), my mind goes straight to the fact that they all require water testing (link to processing contaminants community).
Although tap water is regulated by the Environmental Protection Agency (EPA), bottled water is considered a food product by many regulatory agencies, including the U.S. FDA and the European Commission (links to regulatory agencies). All drinking water must be disinfected to remove microorganisms and ensure it is safe to drink. However, reactions between disinfectants and organic matter in water can produce disinfection byproducts (DBPs), such as haloacetic acids (HAAs) and inorganic oxyhalides, including bromate, chlorite and chlorate. Bromate is formed in water when naturally occurring bromide reacts with ozone used for disinfection. Chlorate and chlorite are produced by chlorine dioxide and chloramine disinfectants. Haloacetic acids (HAAs) are formed when chlorine disinfectants react with organic acids. They are all probable human carcinogens and considered dangerous, even at trace concentrations. This makes testing bottled water for chemicals of upmost importance.
Bromate and Chlorate: Approaches to Testing
The analysis of DBPs is traditionally performed by ion chromatography (IC) (link to IC page). To determine low levels of chlorate, chlorite, and bromate in drinking water with moderate to low ionic-strength matrices, high-capacity hydroxide IC columns (link to product page) or carbonate IC columns (link to product page) can be used with conductivity detection. However, if your bottled water has high concentration of other ions, such as in mineral water, the high ionic strength matrices can overload even the highest capacity columns. This leads to band broadening, which can mask the bromate peak. In this situation, postcolumn derivatization enables determination of very low levels of bromate despite interferences from the matrix. Determination of Trace Concentrations of Chlorite, Bromate, and Chlorate in Bottled Natural Mineral ... (link to application note) is a great resource on the methodologies, and shows expected sensitivities. The hydroxide or carbonate eluent can be generated electrolytically on Reagent-Free™ IC (RFIC™) systems to improve reproducibility and simplify analysis.
Five HAAs, referred to as HAA5, are regulated in much of the world and include: monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid. Some regulatory bodies require monitoring of additional HAAs. For the best detection method that determines the greatest number of HAAs simultaneously, consider using an IC-MS/MS method (link to poster note).
Bottled Water Application Notebook: This 68 page resource is a comprehensive collection of application notes. It begins with a description of the different technologies used for water testing.
Global Food Safety Brochure: This brochure contains a specific page on Processing Contaminants summarizing analysis of disinfection byproducts in bottled water.
Do you analyze DBPs? If so, we’d like to hear what method you use and why.