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Voltammetric Studies of Cadmium‐ and Zinc‐Containing Metallothioneins at Nafion‐Coated Mercury Thin Film Electrodes
Author(s) -
Fu Ying,
Xu Maotian,
Li Xue,
Du Ming,
Wang Jianxiu,
Zhou Feimeng
Publication year - 2008
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200704099
Subject(s) - nafion , zinc , cadmium , electrode , mercury (programming language) , redox , chemistry , inorganic chemistry , overpotential , dropping mercury electrode , nuclear chemistry , electrochemistry , organic chemistry , programming language , computer science
Voltammetric studies of rabbit liver metallothioneins (MTs, containing both Zn and Cd ions) and Zn 7 ‐MT were carried out at Nafion‐coated mercury film electrodes (NCMFEs). The accumulation of MT molecules into the NCMFEs enhances the voltammetric signals and the electrostatic interaction between the Nafion membrane and MT facilitates facile electron transfer reactions. Two well‐defined redox waves, with reduction potential ( E pc ) values at −0.740 and −1.173 V, respectively, were observed. The peak at E pc = −0.740 V is attributable to the reduction of the Cd‐MT complex, whereas that at E pc =−1.173 V was assigned to the reduction of the Zn‐MT complex. Zn 7 ‐MT exhibits only one redox wave with E pc =−1.198 V. The NCMFE was found to be more advantageous than thin mercury film electrode (MFE), because the pristine metal ions in MTs (e.g., Cd 2+ and/or Zn 2+ ) are not significantly replaced by Hg 2+ . The NCMFE is also complementary to Nafion‐coated bismuth film electrode in that it has a greater hydrogen overpotential, which allows the reduction of the Zn‐MT complex to be clearly observed. Moreover, intermetallic compound formation between Cd and Zn appears to be less serious at NCMFEs. Consequently, the amounts of Cd and Zn deposited into the electrode upon the reduction reactions can be quantified more accurately.