Catalytic hydrogen evolution in the presence of methylthiohydantoin-glycine and cobalt(II) ion: a study by cathodic stripping voltammetry at a hanging mercury drop electrode |
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Authors: | Bănică F G Spătaru N |
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Institution: | Norwegian University of Science and Technology, Department of Chemistry (Rosenborg), N-7034 Trondheim, Norway. |
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Abstract: | The carbon-sulfur bond in methylthiohydantoin-glycine (MTH-Gly) is broken during the deposition on the mercury electrode at potentials around -0.1 V versus SCE, giving mercury sulfide which is detected by the characteristic cathodic peak at -0.7 V. If cobalt (II) is also present, the product of the deposition step is a mixture of mercury and cobalt sulfides. During the cathodic scan, the last one is reduced to a transient Co(0) species that catalyses the reduction of hydrogen ion to the hydrogen molecule by a mechanism alike to that emphasized for the Co(II)-sulfide ion system (F.G. B?nic?, N. Sp?taru, T. Sp?taru, Electroanalysis 9 (1997) 1341). This electrode process induces a cathodic peak at -1.4 V that enables the determination of MTH-Gly down to 10(-7) M in the borax buffer at pH 8.5. The possible extension of this method to other classes of organic sulfur compounds is briefly discussed. |
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