Use of 6-Mercapto Purinylazo Resin in Chromium Speciation

The present work describes a procedure of preconcentration, separation and determination of the two forms of chromium, viz. Cr(III) and Cr(VI), in waste water by using 6-mercaptopurine anchored by azo function to a polymeric styrene divinylbenzene (8%) matrix as solid phase extractor. The maximum exchange capacity for Cr (III) at pH 6.5 is 0.44 mmol g^-1 and that for Cr(VI) at pH 1.0 is 1.06 mmol g^-1. In the column operation, the recoveries of both Cr(III) and Cr(VI) in the presence of various foreign ions which are generally present in waste water were examined; it was observed that no such interferences occur in the sorption step. Flow rate optimization studies show that the column is efficient for the separation of both forms of chromium at a flow rate of 1.2 mL min^-1. The metal ion concentration was measured by flame atomic absorption spectrometry. The method has been applied for the separation and speciation of chromium in waste water samples.