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Technical Articles > Bromate
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Technical Articles > Bromate
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Bromate and other oxyhalides are often unwanted byproducts of water
disinfection. We have been analyzing samples for bromate by EPA 300.0
using suppressed conductivity detection. This method is not useful for
low ppb levels (< 15 ppb). EPA
Method 317.0 uses post-column derivatization to increase the
specificity of the test and achieve detection limits below 1 ppb (see
chromatogram below).
In this method, bromate is specifically reacted with a post-column reagent and detected by visible absorbance detection (450 nm). Separation is basically the same as in EPA 300.0. Neither bromide nor chlorate interfere with this analysis. Potential interference from high levels of chlorite can be eliminated by treatment of the sample with ferrous iron, followed by cleanup with an H+ SPE cartridge. This should be done for water samples from treatment plants using chlorine dioxide as a disinfectant. A chromatogram from the EPA method demonstrates the specificity gained from the post-column chemistry versus conductivity detection. |
Water samples may be preserved in the field with ethylenediamine (EDA, 50 ppm) and refrigeration. The holding time after this preservation is 28 days according to the EPA method. Let us know if you need ferrous iron pretreatment or if EDA has been added to your samples, as this information is necessary for us to properly analyze your samples. Our current MDL is 0.4 ug/L with a Minimum Reporting Level (MRL, lowest calibration standard) of 1 ug/L.
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IC-ICPMSAnother alternative is to couple IC with ICPMS. The chromatogram below shows a 10 ug/L standard of bromate and bromide. Detection limits are less than 1 ug/L. |
In this case the chromatography is conducted on a Dionex AS16 column with 35 mm sodium hydroxide. The detector is an ICPMS monitoring the 79 isotope of bromine. |
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