Use of Variamine Blue Dye in Spectrophotometric Determination of Water Soluble Cr(VI) in Portland Cement

Variamine blue dye as chromogenic reagent was used for Portland cement samples in determination of soluble hexavalent chromium. This method was based on the reaction of Cr(VI) with potassium iodide in acidic medium to liberate iodine, which oxidized variamine blue to form a violet colored species having an absorption maximum 556 nm. The extraction of soluble Cr(VI) for quantification in cement was done according to European method. The validity of this method was thoroughly examined by comparing with standard DPC method as well as the accuracy of the method was checked using a standard reference material of National Institute of Standards & Technology (NIST), USA.