Voltammetry as an Alternative Tool for Trace Metal Detection in Peloid Marine Sediments

Abstract

Here was demonstrated for the first time a possible application of abrasive stripping voltammetry in the direct measurement of trace metals in anoxic, sulfidic marine sediments (peloid mud) from a small and shallow (0.2 -1 m) marine lagoon in Central Dalmatia, Croatia. Trace amounts of sample compounds are transferred to the graphite electrode surface and electrochemical reduction or oxidation processes are followed by the cyclic voltammetry in seawater or 0.55 M NaCl as electrolyte. After a preelectrolysis at potentials ranging from À 1.0 to À 1.5 V (vs. SCE) a well-defined anodic stripping peak corresponding to the oxidation of metal deposits generated at deposition potentials is obtained around À 0.74 V (vs. SCE). The same samples were studied by anodic stripping voltammetry at the Hg electrode and inductively coupled plasma-mass spectrometer (ICP-MS). ICP-MS showed higher concentrations of trace metals such as Al, Fe, Mo, Mn. A relatively high concentration of reduced sulfur species (RSS) (10 À3 M) is determined electrochemically in porewater of the peloid mud, indicating that the magnitude of metal enrichment in the sediments is probably controlled by precipitation with sulfide. The same electroanalytical procedure was used for the solid state phase microanalysis of synthetic zinc, ferrous, manganese and copper sulfides. In all of the investigated sulfides after their preliminary electrolytic reduction to the elementary metals which still confined to the electrode surface, similarly positioned anodic stripping peak to that of the sediment sample is recorded.

Electrochemical Quartz Crystal Microbalance Study of FeS Particles Attached to Au Surface

“…Such behavior has been assigned to the complex voltammetry exhibiting characteristics of both adhered and solution phase electrochemistry involving oxidation/dissolution of adhered and reduced species [14]. During negative-going scans that were started from 0 V, a single peak appeared (Fig.…”

“…We have encountered the problem of FeS solid phase electrochemistry when we investigated sulfidic natural samples at paraffin-impregnated graphite electrodes (PIGEs). It became evident that it is impossible to understand the behavior of these systems without a detailed study of the redox processes of different Fe, Fe(I), Fe(II) and FeS phases [14]. Recently, it has been shown that different particulate metal-sulfide species are electroactive on the HMDE by producing cathodic peaks situated at around À 1.0 V (vs. Ag/AgCl) i.e., situated similarly to ones reported for FeS aq species [15 -17].…”

Characterization of Iron Sulfide Species in Model Solutions by Cyclic Voltammetry. Revisiting an Old Problem

“…Recently, during investigation of mercury electrode/sulfide anion/second metal ion system, it has been shown that different metal sulfide particles are electroactive on the Hg and paraffin impregnated graphite electrodes (PIGE) [20][21][22][23][24][25]. The results show the possibility of Hg electrode use for detection of calcogenide nanoparticles in natural samples by adsorptive cathodic stripping voltammetry [20][21][22][23][24][25].…”

Determination of Manganese in Natural Media by Anodic Stripping Voltammetry Using a Rotating Solid Silver Amalgam Electrode

“…It is important to mention that released Mn(II) after some short time is expected to oxidize and form nonelectrolabile colloidal manganese (IV) hydrous oxides, which normally constitutes the main fraction of manganese in oxic waters. To have a more complete knowledge about the speciation of manganese in such a system reaching equilibrium, a combination of the presented technique with, e.g., voltammetric analyses of the solid phase as reported in [50,51] could be interesting.…”