Impact/Purpose:

This presentation by Terri White, Chemist with the Region 4 Science and Ecosystem Support Division, demonstrates the effect of bromide on arsenic and selenium results from the actual analysis of environmental samples with bromide concentrations covering a wide range. The presentation also provides the analyst with procedures to identify and correct this interference.

Description:

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is a complex analytical technology with multielement capabilities, wide linear range, and low detection limits. Though the ICP-MS offers many positive advantages, it is necessary that analysts, whether performing drinking water analysis, a simple matrix, or analyzing a complex matrix, be made aware of the interference challenges that may occur. Many interferences are well documented and predictable. The novice ICP-MS spectroscopist is aware of the problems and knows the solutions to the most common isobaric and polyatomic interferences. Though mentioned in some analytical literature, bromide interferences on arsenic and selenium are not well documented in published environmental analytical methods. Bromide is present in a wide variety of environmental samples including seawater, drinking water, pesticides, pharmaceuticals, photography processes, flame retardants, plant tissue, and fish tissue. Considering the low Maximum Contaminant Level (MCL) for arsenic in drinking water (10 ppb), it is crucial for the analyst to be aware of this interference. If bromide is not monitored and corrected for, false positives will be reported for arsenic and selenium.

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