Determination of Cr(VI) in the Presence of Complexing Agents and Humic Substances by Catalytic Stripping Voltammetry

Abstract

The voltammetric method of Cr(VI) determination in a flow system is proposed. Determinations can be carried out in the simultaneous presence of an excess of Cr(III), complexing agents, humic substances and surfactants. The method is based on the combination of a selective accumulation of the product of Cr(VI) reduction to the metallic state and a very sensitive voltammetric method of chromium determination in the presence of DTPA and nitrates. The calibration graph is linear from 1 Â 10 À9 to 5 Â 10 À8 mol L À1 for accumulation time of 30 s. The relative standard deviation is 5.2% (n ¼ 5) for Cr(VI) concentration 1 Â 10 À8 mol L À1 . The influence of humic and fulvic acids, complexing agents and surfactants on Cr(VI) and the interfering Cr(III) signal is presented. The method was applied to Cr(VI) determination in certified reference material, soil sample, natural water sample and EDTA extracts from soil certified reference material.

Characteristics of Voltammetric Determination and Speciation of Chromium – A Review

“…In the case when chromium(VI) concentration is very low and the analyzed sample cannot be diluted to lower SAS interferences, on-line separation procedures proposed by Korolczuk et al can be utilized [117,121,135]. One of these procedures [135], yielding very reliable results for samples with concentrations of humic acids up to 10 mg/L, features several steps, such as:…”

Hybrid signal processing in voltammetric determination of chromium(VI)

“…The last progresses in catalytic systems of chromium applied in adsorptive stripping voltammetry were presented in Refs. [22,25,26,28,[30][31][32][33][34][35][39][40][41]. In this work determination of Cr(VI) will be done in the presence of DTPA and nitrate on the silver-amalgam electrode with a refreshable surface [28].…”

“…Also modern designs, such as the silver-amalgam electrode with a refreshable surface [28] have been used. The important problem of elimination of the influence of the surface-active substances and organic matter which substantially reduce or completely suppress the signal by the blockage of the electrode surface was also recently investigated [34,36,40]. The voltammetric method coupling adsorptive accumulation and the catalytic reaction, called the catalytic adsorptive stripping voltammetry (CAdSV) method of chromium(VI) determination in the presence of the various complexing and oxidizing or catalytic agents, belongs to the most sensitive analytical methods and has been widely applied in trace analysis.…”

A novel terbium composite nanoparticles: Preparation and selective fluorescence determination of chromium(VI)

“…The trivalent Cr is nontoxic and relatively immobile in nature, whereas the hexavalent Cr which is known to be toxic with potential carcinogenic effects [1] is readily soluble in water, highly toxic and mobile. Concerning about the presence of hexavalent Cr in the environment resulted in the development of numerous analytical techniques for the determination of Cr(VI) in different sample matrices, such as the flow injection analysis [2][3][4], atomic absorption spectrometry [5][6][7][8], on-line selective determination of both species by chromatography [9][10][11][12][13], mass spectrometry [14][15][16], voltammetry [17,18] and solvent extraction which is still one of the most widely used methods for separation and preconcentration [19]. Though these methods have high selectivity and sensitivity, they are somewhat complex, costly, and time consuming.…”