Hexavalent Chromium

Hexavalent chromium, Cr(VI), is the most toxic form of the metal chromium and frequently requires regulatory monitoring as a primary drinking water contaminant in the U.S. at levels as low as 0.2 µg/L (California, Department of Health Services).  Ion chromatography can determine dissolved Cr(VI) as Chromate (CrO₄^2- ) in drinking water, ground water, industrial wastewater, and solid waste extracts. U.S. EPA Method 218.6 specifies the use of the IonPac^® AS7 anion exchange column, post-column reaction with diphenlycarbazide, and UV detection at 530 nm.  With the modifications described in Dionex Application Update 144, an MDL for Cr(VI) as CrO₄^2- of 0.020 µg/L can be achieved.