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2007 | 54 | 1 | 205-211
Article title

Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode

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EN
Abstracts
EN
A potentiometric procedure for cysteine thiol group concentration monitoring in media generating free radicals was developed using a thiol specific silver-mercury electrode. Electrolytic deposition of mercury on a silver wire and treatment with 20 mM cysteine in 0.5 M NaOH were used to produce the electrode. A silver-chloride electrode in saturated KCl was the reference. A glass capillary with 1 M KNO3 in 1% agarose gel was the liquid junction. The electrode responded to cysteine concentration in the range from 0.01 to 20 mM yielding a perfect linear relationship for the dependence of log [cysteine] versus electrode potential [mV], with b0 (constant) = -373.43 [mV], b1 (slope) = -53.82 and correlation coefficient r2 = 0.97. The electrode potential change per decade of cysteine concentration was 57 mV. The minimal measurable signal response was at a cysteine concentration of 0.01 mM. The signal CV amounted to 4-6% for cysteine concentrations of 0.01 to 0.05 mM and to less than 1% for cysteine concentrations of 0.5 to 20 mM. The response time ranged from about 100 s for cysteine concentrations of 0.01 to 0.1 mM to 30 s at higher cysteine concentrations. The standard curve reproducibility was the best at cysteine concentrations from 0.1 to 20 mM. In a reaction medium containing cysteine and copper(II)-histidine complex ([His-Cu]2+) solution in 55 mM phosphate buffer pH 7.4 the electrode adequately responded to changes in cysteine concentration. Beside cysteine, the silver-mercury electrode responded also to thiol groups of homocysteine and glutathione, however, the Nernst equation slope was about half of that for cysteine.
Publisher

Year
Volume
54
Issue
1
Pages
205-211
Physical description
Dates
published
2007
revised
2006-02-02
received
2006-11-06
accepted
2007-02-16
(unknown)
2007-03-09
Contributors
  • Department of Diagnostics, Chair of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Kraków, Poland
  • Department of Diagnostics, Chair of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Kraków, Poland
  • Department of Diagnostics, Chair of Clinical Biochemistry, Collegium Medicum, Jagiellonian University, Kraków, Poland
References
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Document Type
Publication order reference
Identifiers
YADDA identifier
bwmeta1.element.bwnjournal-article-abpv54p205kz
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