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Constant Current Chronopotentiometric Stripping Analysis of Bioactive Peptides at Mercury and Carbon Electrodes
Author(s) -
Tomschik Miroslav,
Havran Luděk,
Fojta Miroslav,
Paleček Emil
Publication year - 1998
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/(sici)1521-4109(199805)10:6<403::aid-elan403>3.0.co;2-2
Subject(s) - chemistry , hanging mercury drop electrode , electrode , dropping mercury electrode , angiotensin ii , carbon paste electrode , peptide , chromatography , inorganic chemistry , analytical chemistry (journal) , electrochemistry , voltammetry , cyclic voltammetry , biochemistry , receptor
Constant current derivative chronopotentiometric stripping analysis (CPSA) was used to study bioactive peptides [Lys 8 ]‐vasopressin and angiotensin II at carbon paste electrode (CPE) and hanging mercury drop electrode (HMDE). Both peptides contain a single tyrosine residue which is oxidized at CPE close to +0.6 V (against Ag/AgCl/3 M KCl electrode) producing peak Y; this peak was by about 15 mV more positive in vasopressin than in angiotensin II. At HMDE vasopressin yielded peak S due to the reduction of the disulfidic bond in the peptide. No peak S was observed with angiotensin II as it does not contain any cystine/cysteine residues. Vasopressin produced different catalytic hydrogen reduction signals in media with cobalt ion and in media not containing any metal ion. The signal produced in the latter media (peak H), which appeared close to −1.7 V, was well separated from the background. No catalytic hydrogen reduction signal was obtained with angiotensin II. The above mentioned CPSA signals can be applied for the determination of the respective peptide at nanomolar concentrations. The least sensitive peak S appears which requires at least 100 nM vasopressin concentration at moderate accumulation time. By two orders of magnitude, higher sensitivities can be obtained with peaks Y and H. In measuring these peaks CPSA shows significant advantages over the voltammetric stripping techniques.