This document contains references to Varian. Please note that Varian, Inc. is now part of Agilent Technologies. For more information, go to www.agilent.com/chem.
The document details a colorimetric method for determining dissolved hexavalent chromium content in water. The procedure involves reacting the sample with 1,5-diphenylcarbazide in an acid medium to develop a reddish-purple color, which is then measured at 540 nm using the DMS 90 spectrophotometer.
The absorbance of the developed color is measured at 540 nm.
A slit width of 2 nm was used because the chromium peak is broad.
The test solution should be allowed to stand for 10 minutes to ensure consistent results.
Iron (III), vanadium, molybdenum, mercury, and nitrites have adverse effects on the color development.