Electrochemical characterization and determination of N-acetylpenicillamine thionitrite

Square-wave voltammetry and cyclic voltammetry are used to investigate the electrochemistry of N-acetylpenicillamine thionitrate. Thionitrites have been proposed as intracellular intermediates in organic nitrate-induced mammalian vasodilatation. Although these intermediates have been demonstrated indirectly, no sensitive direct determinations have been developed. The electrochemical behavior of this thionitrite at mercury and vitreous carbon electrodes in buffered aqueous media is here described. At mercury, below pH 6.0 one reversible anodic wave and one irreversible cathodic wave are seen. On solid electrodes, only the irreversible wave is present. A determination for thionitrite based on the irreversible cathodic wave is presented. When square-wave voltammetry is used, the current response is linear with concentration in the range of 1-200 μg l^-1 (40 μM-1.5 mM). N-Acetylpenicillamine does not interfere.