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Constant Current Stripping Chronopotentiometry for the Study of Adsorbing Inert and Electrochemically Nonreversible Metal Complexes at Low Concentrations: Application to Cd and Zn Metallothioneins
Author(s) -
Serrano Núria,
Šestáková Ivana,
DíazCruz José Manuel
Publication year - 2006
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.200503390
Subject(s) - chemistry , cadmium , analytical chemistry (journal) , stripping (fiber) , hanging mercury drop electrode , metallothionein , metal , metal ions in aqueous solution , anodic stripping voltammetry , voltammetry , inert gas , inorganic chemistry , inert , ion , zinc , adsorption , electrode , electrochemistry , chromatography , materials science , organic chemistry , composite material
Constant current chronopotentiometric stripping analysis using adsorptive accumulation and negative stripping current (AdSCP) was applied for the study of behavior of rabbit liver Cd‐Zn and Zn metallothionein (Cd‐Zn‐MT, ZnMT) on hanging mercury drop electrode. Electrochemically inert or labile behavior of complexes can be distinguished with the application of high (1000 nA) or low (100 to 20 nA) current. Using high current, no influence of added Cd 2+ or Zn 2+ ions on the reduction of Cd(II) or Zn(II) complexed within MT molecule was observed, except of additions of Cd 2+ to ZnMT, where bound Zn(II) was substituted by cadmium ions. With lowering of stripping current and increasing concentration of added Cd 2+ or Zn 2+ ions in solution progressive formation of reorganized complex with labile behavior is observed. Parallel measurement using DC voltammetry with different rates of polarization or differential pulse voltammetry were in agreement with AdSCP measurement. However, only chronopotentiometric method combines good sensitivity and signal separation at μM concentrations, inevitable in MT studies.