Abstract

A rapid and sensitive method is described for flow injection spectrophotometric determination of trace Cr(VI) and total chromium in tannery effluent. The method is based upon the classical reaction of Cr(VI) with diphenylcarbazide (DPC) to form a water-soluble complex (λmax = 540nm). Cr(III) reacts with DPC only after its on-line oxidation to Cr(VI) by Ce(SO4)2. Under the optimized conditions, the calibration curves were linear over the range 5-100μg l-1 and 20-200μg l-1 for Cr(VI) and total chromium, respectively, while the precision close to the quantification limit was satisfactory in both cases (sr = 0.49% for Cr(VI) and 0.94% for total chromium (n = 10) at the same level, 50μg l-1, respectively). The application of the method to the analysis of tannery effluent gave accurate results based on recovery studies (98.7-103.3%). Analytical results of total chromium tannery effluent were in good agreement with that of reference method.