Constant Current Stripping Chronopotentiometry for the Study of Adsorbing Inert and Electrochemically Nonreversible Metal Complexes at Low Concentrations: Application to Cd and Zn Metallothioneins
✍ Scribed by Núria Serrano; Ivana Šestáková; José Manuel Díaz-Cruz
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 145 KB
- Volume
- 18
- Category
- Article
- ISSN
- 1040-0397
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✦ Synopsis
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 2þ or Zn 2þ ions on the reduction of Cd(II) or Zn(II) complexed within MT molecule was observed, except of additions of Cd 2þ to ZnMT, where bound Zn(II) was substituted by cadmium ions. With lowering of stripping current and increasing concentration of added Cd 2þ or Zn 2þ 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 mM concentrations, inevitable in MT studies.