ISO 18412:2005 specifies a method for the determination of chromium(VI) in drinking water in mass concentrations between 2 micrograms per litre and 50 micrograms per litre. For the determination of higher concentrations, the sample is diluted prior to analysis. The method may also be applied to weakly polluted ground and surface water, provided the matrix does not contain interfering reducing agents. This method was not used for estuarine water and seawater, so the user is responsible for the validation of the method for these matrices.