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Trace measurements of insulin by potentiometric stripping analysis at carbon paste electrodes
Author(s) -
Wang Joseph,
Rivas Gustavo,
Cai Xiaohua,
Chicharro Manuel,
Farias Percio A. M.,
Palecek Emil
Publication year - 1996
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.1140081010
Subject(s) - potentiometric titration , stripping (fiber) , chemistry , electrolyte , electrode , detection limit , myoglobin , analytical chemistry (journal) , carbon paste electrode , electroanalytical method , anodic stripping voltammetry , chromatography , inorganic chemistry , materials science , electrochemistry , cyclic voltammetry , biochemistry , composite material
A potentiometric stripping method for trace measurements of insulin at carbon paste electrodes is described. The method is based on the controlled adsorptive accumulation of this polypeptide hormone at the anodically pretreated carbon surface followed by constant‐current chronopotentiometric measurements of the surface species. A well‐defined peak, associated with the oxidation of the tyrosine residues, is observed over the flat baseline of the potentiometric stripping operation. Variables of the pretreatment and measurement steps are optimized to offer a detection limit of 2 × 10 −9 M after 5 min preconcentration. Excess of nunierous potential interferences does not influence the response observed after transferring the electrode (with the accumulated insulin) to a blank electrolyte solution. A similar protocol is described for trace measurements of the protein myoglobin.