Much has been written on bromate methods (link to article on comparison of regulated methods) over the years, but what still confuses some people are the multitude of methods available for the analysis of bromate. As a well known toxic disinfection by-product typically formed from the ozonation of water containing bromide, bromate is regulated in many countries around the world. The U.S. Environmental Protection Agency (EPA) has established a regulatory maximum contaminant level (MCL) of 10 µg/L of bromated in drinking water and a maximum contaminant level goal (MCLG) of 0.8 µg/L. The World Health organization (WHO) also recommends an MCL of 10 ug/L of bromated in their publication, titled, Bromate in Drinking Water, (downloadable PDF). The Japanese Ministry of Health, Labor and Welfare has a similar level. In addition, the European Commission established a lower MCL of 3 μg/L bromate in natural mineral waters and spring water treated by ozonation.
The determination of trace concentrations of bromate and other oxyhalides in high-ionic-strength matrices can be very challenging. Bromate in drinking-water may be measured by ion chromatography using conductivity detection (EPA Method 300.1; ISO 15061), ultraviolet/visible absorbance detection (EPA Method 317.0/326; ISO 11206). All methods were initially developed using carbonate eluents with the best available capacity columns. Since the early 90’s, major improvements have been made to improve column capacity along with electrolytic eluent generation for hydroxide eluent. Electrolytic eluent generation and electrolytic suppression allow “just add water” capability thus combining robustness, sensitivity and ease-of-use. Side-by-side experiments using clearly demonstrate the better sensitivity when using hydroxide eluents, as described in Application Note 184, Determination of Trace Concentrations of Chlorite, Bromate, and Chlorate in Bottled Natural Mineral Waters (downloadable PDF).
It should be mentioned that electrolytic eluent generation (link to downloadable PDF on such systems) and not eluent dilution, provide the best results. People have tried merely diluting a concentrated stock with DI water in an online form that can distort results, and give inconsistent, long term performance. Using electrolytically generated eluents gives pure eluent in real time, before contaminants can get in. Not so with an online diluter. We recently developed a new column that allows the use of hydroxide eluent and provides greater bromate sensitivity in samples with preservatives and surrogates (link to description of column and a downloadable application note).
Because many water utilities have high chloride concentrations, problematic issues with reliable post column derivatization, and eliminating sample preparation, the EPA Office of Ground Water and Drinking Water approved EPA Method 302 which has “just add water capability” coupled with 2-D ion chromatography (2D-IC) that eliminates matrix, improves bromate detection up to 100-fold in a second dimension and provides orthogonal separation to eliminate potential false positives. The article mentioned in the first line of this blog post also describes the benefits of 2-D IC. Public water utilities are already using 2-D ion chromatography for compliance monitoring as discussed in this on-demand webinar, titled, Advanced IC Applications for Compliance Monitoring in Drinking Water Monitoring Bromide & Bromate by EPA Methods 300.1 & 302 with Advances in 2D Capillary IC. They realize the benefit of 2-D IC and its ability to simultaneously monitor bromide and bromate in the first dimension and second dimensions, respectively. This allows them to better understand seasonal bromide fluctuations from high and low source water flows. With this knowledge they can better operate their drinking water disinfection process, reduce disinfection costs and avoid the disposal costs of the toxic post-column reagent o-dianisidine if using EPA 317.
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Richard Jack is currently the Director of Vertical Marketing for the Environmental and Industrial markets for the Chromatography and Mass Spectrometry Division at Thermo Fisher Scientific Inc., a Scientific Advisor to the U.S. EPA Hydraulic Fracturing Research Advisory Panel, a coauthor on the U.S. EPA Method 557, and has drafted several ASTM methods. Richard facilitates development of new applications, instrumentation, column chemistries, and software that provide customers real solutions. Richard’s breadth of experience spans designing chromatography analytical instrumentation including pumps, autosamplers, and detectors. Richard received his Ph.D. in Biochemistry and Anaerobic Microbiology from Virginia Tech University in Blacksburg, VA, where he was involved in vaccine development and, later, worked as an environmental scientist in bioremediation of toxic compounds in soils. He received his Masters in Ecology from the University of Tennessee in Knoxville, TN.