Cathodic Stripping Voltammetry of Sulphur-Containing Amino Acids and Peptides in the Presence of Nickel Ion. Catalytic and Inhibiting Effects
作者:
F.G. Bãnicã,
A.G. Fogg,
Ana Ion,
J.C. Moreira,
期刊:
Analytical Letters
(Taylor Available online 1996)
卷期:
Volume 29,
issue 8
页码: 1415-1429
ISSN:0003-2719
年代: 1996
DOI:10.1080/00032719608001491
出版商: Taylor & Francis Group
关键词: stripping voltammetry;catalytic currents;thiols;disulphides;amino acids;peptides;nickel
数据来源: Taylor
摘要:
The paper reviews recent studies on the effect of addition of Ni(II) in the cathodic stripping voltammetry of the following compounds: cysteine, penicillamine, cystine, glutathione (either reduced or oxidised) and N-acetylcysteine. With the exception of N-acetylcysteine, the above compounds give a cathodic stripping peak at -0.6 V (vs. Ag/AgCl, 3 M KCl electrode) which is due to the catalytic reduction of nickel ion. Even in the case of the disulphides the actual catalyst is the thiol produced by the cleavage of the -S-S- bond during the accumulation step. The catalytic peak enables the detection of the analyte with a better selectivity than is obtained with the stripping peak due to the reduction of mercury thiolates. In addition, Ni(II) suppresses the mercury thiolate peak of ligands such as cysteine or penicillamine, but does not modify the behaviour of thiols with low complexing properties (such as N-acetylcysteine). Consequently, compounds such as cysteine and its N-acyl derivatives can be determined simultaneously by means of the catalytic peak and the mercury thiolate peak (at -0.4 V) respectively.
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