Electrochemical determination of thiosulfate in seawater in the presence of elemental sulfur and sulfide

Abstract

Linear sweep voltammetry (LSV) has been used for the direct determination of thiosulfate in the mixture with other sulfur species (sulfide. elemental sulfur) in 0.5 M NaCV3 x 10-'M NaHC03, pH 8.3 as supporting electrolyte and in natural seawater samples. The determination is based on anodic depolarization reaction between sulfur and the mercury electrode. Investigations were carried out over wide concentration ranges, from to 10-4M of thiosulfate in the solution. In seawater conditions (pH 8.3) thiosulfate displays a voltammetric peak at about -0.15 V, and sulfide andor elemental sulfur between -0.6 and -0.7 V (vs. Ag/AgCl). Based on the appearance of the voltammetric peaks of thiosulfate and sulfide at different potentials, and using different experimental conditions, i.e., accumulation at different starting potentials [ E = 0 or E = -0.2 V (vs. Ag/AgCI)J, a method for the direct determination of thiosulfate and sulfide in the mixture has been proposed. The direct method of thiosulfate determination in seawater can be used if the concentrations of sulfide are lower than 5 x lo-' M. Higher concentrations of sulfide have to be decreased by acidifying and degassing the sample to prevent interferences. The method was applied for the analysis of sulfur species in marine samples from anoxic environment.

Zinc sulfide surface formation on Hg electrode during cyclic voltammetric scan: an implication for previous and future research studies on metal sulfide systems

“…3a). Since the electrochemical behavior of dissolved S 0 at the Hg electrode is the same as that reported for sulfide, at potentials more positive than −0.6 V HgS will be formed [6]. During the negative CV scan, Zn 2+ from the solution will replace Hg from HgS and at the C3 potential ZnS adlayer will be formed.…”

“…Usually, well-separated voltammetric peaks are observed for the anodic deposition of HgS, but only one peak is observed for the cathodic dissolution of HgS [1][2][3][4]. The reduction of HgS layers is often used for the quantitative determination of sulfur species in natural waters [3][4][5][6].…”

Organic matter characterization in Barents Sea and eastern Arctic Ocean during summer

“…Determination of reduced organic and inorganic sulfur in seawater samples was performed by applying linear sweep voltammetry (LSV) (Ciglenečki and Ćosović, 1997;Krznarić et al, 2001). In .…”

Distribution of Redox-sensitive Elements in Bottom Waters, Porewaters and Sediments of Rogoznica Lake (Croatia) in Both Oxic and Anoxic Conditions

“…RSS (sulphide, elemental sulphur, polysulphide) were determined electrochemically in the overlying lake water and sediment porewater by linear sweep voltammetry (LSV) (Ciglenečki & Ćosović, 1997).…”