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Electrochemical oxidation of cysteine at a film gold modified carbon fiber microelectrode its application in a flow-through voltammetric sensor.

Wang LH, Huang WS - Sensors (Basel) (2012)

Bottom Line: The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents.For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L(-1) was found.The limit of quantification for cysteine was below 60 ng·mL(-1).

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, Tainan, Taiwan. e201466.wang@msa.hinet.net

ABSTRACT
A flow-electrolytical cell containing a strand of micro Au modified carbon fiber electrodes (CFE) has been designedand characterized for use in a voltammatric detector for detecting cysteine using high-performance liquid chromatography. Cysteine is more efficiently electrochemical oxidized on a Au /CFE than a bare gold and carbon fiber electrode. The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents. For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L(-1) was found. The limit of quantification for cysteine was below 60 ng·mL(-1).

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Cyclic voltammograms of cysteine 30.0 mg·L−1 in Britton-Robinson buffer (pH 5.33) at various potential scan rates: (a) 5 mV/s; (b) 10 mV/s; (c) 12.5 mV/s; (d) 25 mV/s; (e) 50 mV/s; (f) 100 mV/s (g) 200 mV/s.
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f6-sensors-12-03562: Cyclic voltammograms of cysteine 30.0 mg·L−1 in Britton-Robinson buffer (pH 5.33) at various potential scan rates: (a) 5 mV/s; (b) 10 mV/s; (c) 12.5 mV/s; (d) 25 mV/s; (e) 50 mV/s; (f) 100 mV/s (g) 200 mV/s.

Mentions: Current-potential curves were plotted using different concentration of cysteine. Experiments were performed at pH 2.81 and 5.33 (results not shown) and pH 3.56 (Figure 5). Cyclic voltammograms of cysteine in Britton-Robinson buffer (pH 3.56) solution at an Au/CFE electrode show one well-defined oxidation (compared to Figure 2 scan rate 10 mV/s) that is due to rapid scan rate 50 mV/s of a portion of the cysteine which diffuses to the electrode surface, and proceeds rapidly as a result of a catalytic effect of the gold. Cyclic voltammograms of different concentrations of cysteine at an Au/CFE electrode are shown in Figure 5, the regression equation being y = 0.306 x + 6.61, the correlation coefficient r = 0.9921. The influence of the potential scan rate on the electrochemical response was studied at pH 5.33 (Figure 6). Good linearity was observed between the peak height (current) and the square root of scan rate (v1/2) (Figure 7(A)).


Electrochemical oxidation of cysteine at a film gold modified carbon fiber microelectrode its application in a flow-through voltammetric sensor.

Wang LH, Huang WS - Sensors (Basel) (2012)

Cyclic voltammograms of cysteine 30.0 mg·L−1 in Britton-Robinson buffer (pH 5.33) at various potential scan rates: (a) 5 mV/s; (b) 10 mV/s; (c) 12.5 mV/s; (d) 25 mV/s; (e) 50 mV/s; (f) 100 mV/s (g) 200 mV/s.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376634&req=5

f6-sensors-12-03562: Cyclic voltammograms of cysteine 30.0 mg·L−1 in Britton-Robinson buffer (pH 5.33) at various potential scan rates: (a) 5 mV/s; (b) 10 mV/s; (c) 12.5 mV/s; (d) 25 mV/s; (e) 50 mV/s; (f) 100 mV/s (g) 200 mV/s.
Mentions: Current-potential curves were plotted using different concentration of cysteine. Experiments were performed at pH 2.81 and 5.33 (results not shown) and pH 3.56 (Figure 5). Cyclic voltammograms of cysteine in Britton-Robinson buffer (pH 3.56) solution at an Au/CFE electrode show one well-defined oxidation (compared to Figure 2 scan rate 10 mV/s) that is due to rapid scan rate 50 mV/s of a portion of the cysteine which diffuses to the electrode surface, and proceeds rapidly as a result of a catalytic effect of the gold. Cyclic voltammograms of different concentrations of cysteine at an Au/CFE electrode are shown in Figure 5, the regression equation being y = 0.306 x + 6.61, the correlation coefficient r = 0.9921. The influence of the potential scan rate on the electrochemical response was studied at pH 5.33 (Figure 6). Good linearity was observed between the peak height (current) and the square root of scan rate (v1/2) (Figure 7(A)).

Bottom Line: The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents.For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L(-1) was found.The limit of quantification for cysteine was below 60 ng·mL(-1).

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Chemistry, Chia Nan University of Pharmacy and Science, Tainan, Taiwan. e201466.wang@msa.hinet.net

ABSTRACT
A flow-electrolytical cell containing a strand of micro Au modified carbon fiber electrodes (CFE) has been designedand characterized for use in a voltammatric detector for detecting cysteine using high-performance liquid chromatography. Cysteine is more efficiently electrochemical oxidized on a Au /CFE than a bare gold and carbon fiber electrode. The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents. For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L(-1) was found. The limit of quantification for cysteine was below 60 ng·mL(-1).

Show MeSH