Voltammetric determination of traces of Cr(VI) in the flow system in the presence of bipyridyne

The voltammetric method of Cr(VI) determinations in the flow system, based on the combination of selective accumulation of the product of Cr(VI) reduction on HMDE and a very sensitive method of chromium determination in the presence of bipyridine [Z. Gao K.S. Slow, Electroanalysis 8 (1996) 602] is proposed. The calibration graphs were linear from 3 x 10(-9) to 3 x 10(-8) and from 5 x 10(-10) to 5 x 10(-9) mol l(-1) for accumulation times 120 and 600 s, respectively. The relative standard deviation (R.S.D.) was 6.5% (n = 5) for Cr(VI) concentration 1 x 10(-8) mol l(-1) and the accumulation time 120 s. The influence of foreign ions commonly present in water samples is presented. Validation of the method was made by comparison of the results of analyses of tap water by another electrochemical method and by recovery test for river and mineral water. (C) 1999 Elsevier Science B.V. All rights reserved.