The electrooxidation of N02-to N03_ on smooth and platinized platinum in neutral and weakly acidic aqueous media has been investigated with a voltammetric technique. The experimental behavior of the anodic voltammetric curve of N02~on platinized platinum as well as the behavior of the potentiostatic current-time curves

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The behaviour of HgII and HgII-thiol complexes (RSH=-cysteine, -penicillamine, propane-2-thiol, glutathione, thiosalicylic acid ) following their reduction with alkaline sodium tetrahydroborate to give Hg0 has been studied by using a continuous flow reaction system coupled with atomic fluorescence spectrometric (AFS ) detection. The quantitative reduction of HgII to Hg0 takes place with a specific amount of sodium tetrahydroborate according to the stoichiometric reaction of mercury with alkaline NaBH 4. The complete reduction of HgII-thiol complexes to Hg0 requires a molar excess of NaBH 4 of up to six orders of magnitude, depending on the type of complex. Under an appropriate excess of reductant, HgII and its thiol complexes are not distinguishable giving the same AF molar response. The method allows the discrimination of HgII from HgII-thiol complexes without any preliminary separation. Applications to the indirect titration of thiols and to the determination of the number of accessible KSH groups in pure ovalbumin samples are reported. stoichiometry, KSKHgKR, and have been preferred to HgII,