Bromate in drinking water: new testing method fit for purpose

A study carried out by the European Commission's Joint Research Centre (JRC) has opened the door to replacing the current standard method for measuring bromate in drinking water with an improved method, which is more suitable for the tighter current legislative limits.

According to European legislation, bromate is one of 48 microbiological and chemical parameters that must be monitored and tested regularly. The aim is to ensure wholesome and clean drinking water for consumers. The Drinking Water Directive ruled that bromate concentrations in drinking water should be less than 10 micrograms per litre, and Member States were given until the end of 2008, at the latest, to meet this value. This extremely low threshold (the previous limit was 25 micrograms per litre), is the reason legislators and scientists are working to replace the current standard testing method.

A new analytical method

Upon request from the Commission's Directorate-General for Environment in 2009, the JRC's Institute for Reference Materials and Measurements (IRMM) in Geel, Belgium, organised a validation study of a new analytical method (draft standard method ISO/DIS 11206) to measure bromate in different types of water. The validation study was organised in collaboration with the International Organisation for Standardization (ISO).

Seventeen laboratories from nine countries participated in the exercise. The laboratories received samples of different drinking water types (soft, hard, mineral) and other water types (swimming pool water, untreated water, synthetic bromate standard solution), and the laboratories were asked to determine the bromate content in the water samples by strictly following the instructions of the new method, and report their results back to the JRC.

Based on the statistical evaluation of the results from this collaborative trial it was concluded that the proposed method is suitable for the quantitative determination of bromate in drinking water, as required by European legislation, as well as in other types of water. All water samples (except one) were spiked at levels below the so-called legislative parametric value of 10 μ/ L, which made this exercise particularly challenging.

The trueness and precision of the new method are far below the maximum allowed deviation (± 25%) from the parametric value, thus the method fits its intended analytical purpose. Furthermore, the present method has the benefit of achieving higher precision and lower deviation to the reference values in comparison to the former standard method.

Source: Institute for Reference Materials and Measurements (IRMM)