Abstract
Chromiym(VI) in fresh concrete samples has been tested qualitatively by a diphenylcarbazide method, a barium chromate method, and a perchromate method. Chromium(VI) was separated from sulfate by precipitating silver chromate since, for ion chromatography, large amount of sulfate ion interfere. The silver chromate thus obtained was dissolved in ammoniacal solution. Ion chromatography was carried out under the condition: eluent, 1 mM potassium hydorogen phthalate/10% acetonitrile (pH 7.10) flow rate, 1.2 m//min. Chromium(VI) was also estimated spectrophotometrically by a direct colorimetry of the yellow chromate ion, or by a more sensitive method involving a reaction between the dichromate and diphenylcarbazide. Analysed samples contained between 2-12 mg of chromium (VI) per kg of cement.
