Application of voltammetric method of total chromium determination in the presence of cupferron for selective determination of Cr(VI) in water samples

A voltammetric method of Cr(VI) determination in a flow system based on the combination of selective accumulation of the product of Cr(VI) reduction on hanging mercury drop electrode and a very sensitive method of chromium determination in the presence of cupferron previously described 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 of 120 and 600 s, respectively. The detection limit for the accumulation time of 600 s was 9 x 10(-11) mol L-1. The relative standard deviation was 5.1% (n = 5) for Cr(VI) concentration 1 x 10(-8) mol L-1 and the accumulation time of 120 s. The influence of foreign ions commonly present in water samples is presented. The validation of the method was made by studying the recovery of Cr(VI) from spiked natural water samples. (C) 1999 Academic Press.