This method is used for the determination of hexavalent chromium in water/wastewater. The lowest detection range of this method is 4 to 300 µg/L. However, this method is applicable to other ranges.
Hexavalent chromium [Cr(VI)] reacts with diphenylcarbazide in an acid medium to form a red-violet complex that is measured at 540 nm.
Hexavalent molybdenum and mercury interfere if present in concentrations greater than 200 mg/L. Vanadium will interfere if present in quantities greater than ten times that of hexavalent chromium. The yellow color produced by the reaction with iron does not interfere at the analytical wavelength.