Access to safe drinking water is essential to health and is a basic human right (see the World Health Organization’s Guidelines for Drinking-water Quality). A key part of the water purification process is treatment by either ozonation or the addition of chlorinated compounds to remove microorganisms that could induce illness. An unfortunate side effect of this treatment is the formation of toxic disinfection byproducts (DBPs), which include haloacetic acids, trihalomethanes, and the oxyhalides chlorate, chlorite, and bromate.
Determining DBPs in Water
There are many options available for determining DBPs in water, detailed in the National Primary Drinking Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule. Bromate is no exception. For this analyte, methods primarily use Ion Chromatography (IC) (see Richard Jack’s blog post for more details), although a photometric method has recently been introduced. The specific method chosen for bromate determination will be mainly dictated by the detection level required and whether or not that method has received regulatory agency approval.
Advantages of Ion Chromatography
When comparing IC methods to those that use photometric detection, IC has the clear advantage. Here’s why:
Bromate was among the first set of water contaminants for which an analytical method was developed by the U.S. Environmental Protection Agency (EPA) in the early 1990s. Since that time, IC systems and column chemistry have been continuously refined, increasing sensitivity and ease of analysis.
There are six IC methods approved by the EPA, two by the International Organization for Standardization (ISO), and one by ASTM International, while there are no photometric methods that have been approved for bromate determination.
Samples can be directly injected without any pretreatment. For spectrophotometry, extensive sample preparation is required.
Chromatography can separate bromate from matrix components that can interfere with detection and preclude the use of other methods, such as those that use spectrophotometry.
Multiple analytes, including the DBPs chlorite and chlorate, are determined in a single run. These often also need to be reported.
If lower detection limits are needed, an IC system can be readily configured to include additional modules or higher-sensitivity detectors.
See these additional resources for more information about drinking water quality and bromate analysis using IC.