Photometric bromate determination: Faster drinking water analysis
Merck Millipore has developed a new method for measuring bromate in drinking water photometrically. The analyses are much less expensive and complex than the standard ion chromatography method, and provide results much more quickly. Extensive test series conducted by Merck confirm that the photometric method provides results of comparable reliability to those obtained by ion chromatography.
Water treatment methods are routinely used to ensure a safe drinking water supply. However, these processes can sometimes lead to unwanted side reactions that introduce compounds, such as bromate, into the water. The German drinking water regulations specify a limit value of 10 µg/l. The measurement of the bromate is described in ISO 15061:2001, making this method mandatory in Germany.
The new Merck Millipore process uses photometry: the method is based on the reaction of 3,3’-Dimethylnaphtidin with iodide and bromate to produce a red radical cation whose absorbance is determined photometrically. The more bromate contained in the sample, the more intense the color.
Spectroquant® pre-programmed for correct determination
If a Spectroquant® photometer is used, calibration becomes unnecessary: Merck instruments are pre-programmed with a curve for correct bromate determination from 0.003 to 0.120 µg/l. Calibration is very complex in conventional photometry with other instruments.
The sample preparation and bromate analysis is described in a detailed application note from Merck. The sample is first concentrated for increased sensitivity, then mixed with reagents. After about 30 minutes, the color has fully developed and the bromate content can be measured with the Spectroquant® photometer.