Bromide is a negative charged ion (anion) consisting of the element Bromine with another element or group. It can be found in nature but in relatively small quantities, for example the naturally occurring concentration of Bromide in freshwaters is between Trace amounts and 0.5 mg/L.
Potable water
Bromide in treated drinking water is a serious concern. The Bromide ion itself is of relatively low toxicity however, it’s presence causes the possibility of the formation of mutagenic disinfection by-products (DBPs). When water is treated with ozone, it can react with naturally occurring Bromide ions in the water to form Bromate a compound which can cause numerous health concerns in humans. Other concerns are the formation and occurrence of Bromacil, methyl bromide, PBDEs and EDB.
Of particular interest at present is the use of saline waters which will typically have a larger background concentration of Bromide than freshwaters. Saline waters are increasingly being used in different parts of the world where access to freshwater is scarce for both drinking and recreation.
Bromine has also had use in disinfectant in both treated water and environments such as swimming pools however less so with drinking water because of the concern of DBPs.
Pollution tracking
Bromide is also employed as a tracer to track the path and fate of fertilizers in the environment. It is preferred to tracers such as sodium chloride because the naturally occurring concentration is substantially lower. It has been used in a wide range of environments including groundwater and soils with an emphasis on buffer zones and farming plots.
Anthropogenic Bromide
With the use as a tracer, Bromide can be leached into water courses from pollution tracking. Of growing concern is the production from industry, including pharmaceutical, plastic and electronic where bromide and bromine compounds are used both in manufacturing and as medical ingredients. There is now a growing awareness of how by-products and compounds in direct use keep finding their way into water courses which can present further risks.
Proteus uses a solid-state ISE to measure Bromide with a range of 0.2 – 79,900 ppm.
It’s main interferences are I–, Cl–, S2–, CN– and NH3.
