engleski

Adsorptive Transfer Chronopotentiometric Stripping of Sulphated Polysaccharides

Sulphated polysaccharides (S-PSs) act as a “presodium” catalyst of hydrogen evolution on mercury electrode in a buffered sodium chloride solution. Two catalytic peaks named peak H'PS and peak HPS appear as a result of hydrogen evolution. This work presents the catalytic effect of S-PS placed in seawater (pH 8.2) where direct stripping did not give catalytic peaks. An adsorptive transfer procedure (AdT) was applied in order to enable the analysis of S-PS in seawater. Accumulated S-PS was transferred from seawater to buffered sodium chloride solution (pH 5.1) which was the stripping electrolyte. Chronopotentiometric stripping method (CPS) was applied with stripping done by constant reduction current. Model S-PSs chondroitin sulphate, ι-, κ- and λ - carrageenans, and nonsulphated PS dextran, having different structures and thus making different conformation in water solution, were reagents in AdT experiments. A static mercury drop electrode (drop size 0.40 mm2) was a working electrode. Results have shown that the adsorbed layer of S-PS was very stable after the transfer step. The impact of measurement conditions (accumulation potential and time, stripping current and S-PS concentrations) on peak HPS height and potential was examined. Detection limit was found to be in the range of pmol dm-3. AdT procedure coupled with CPS method appears to be useful for S-PS analysis in natural seawater where S-PSs are identified as main constituents of organic matter.

Sulphated polysaccharides; Adsorptive transfer chronopotentiometric stripping; Peak H; Seawater; Buffer

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