Voltammetric determination of Cr(VI) in a flow system in the presence of diethylenetriaminepentaacetic acid (DTPA) following its deposition in the metallic state Original Research Article

A sensitive and very selective procedure for voltammetric determination of traces of Cr(VI) in the flow system is presented. The calibration graph is linear from 1×10−9 to 1×10−7 mol l−1 and from 1×10−10 to 1×10−8 mol l−1 for deposition times 60 and 240 s, respectively. The relative standard deviation for 1×10−8 mol l−1 Cr(VI) is 4.3% (n=5). The detection limit estimated from 3σ for low concentration of Cr(VI) and the deposition time 240 s is 3×10−11 mol l−1 (1.5 ng l−1). The method is free from the interference from surface active compounds at the concentration typically present in natural water samples. The influence of common foreign ions is also presented. The accuracy of the method was tested by studying the recovery of Cr(VI) from spiked natural water samples.