Spectrophotometric Determination of Chromium (VI) in Nitric Acid by Means of Solvent Extraction with Molten Mixtures of Naphthalene and Biphenyl

A method for the Spectrophotometric determination of chromium (Vl) after extraction of its ternary complex with ammonium pyrrolidinedithiocarbamate (APDC) as the chelating agent in to molten naphthalene – biphenyl has been developed. The Cr-(PDC)3 complex in a nitric acid solution is quantitatively extracted from into molten naphthalene – biphenyl at about 70 °C. Organic phase can be obtained as a solid lump on the surface of the aqueous phase, making its collection simple. Therefore the organic phase dissolved in methyl isobutyl ketone (MIBK). The chromium in this solution is than determined by using atomic absorption technique. The effect of different variables such as acid concentration, naphthalene– biphenyl, shaking time, foreign ions and APDC concentration was investigated.