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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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Chromatograms obtained using Au electrode (A) and Au/CFE (B) for cysteine (0.5 mg·L−1) and (C) blank solution. Conditions: electrode, Au–modified carbon fiber detector (length: 8 cm); stationary phase, ThermoQuest Hypersil SCX (particle size 5 μm, 250 mm × 4.6 mm i.d.); Mobile phase, methanol: water (20:80 v/v) containing 1.0 mM acetate buffer (pH 4.65); detection conditions: pulsed conditions, t1 =180 ms, t2 = 180 ms. Initial potential E1(det) = +1.0 V, final potential E2(ox)= +2.0 V, flow rate, 0.5 mL·min−1.
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f12-sensors-12-03562: Chromatograms obtained using Au electrode (A) and Au/CFE (B) for cysteine (0.5 mg·L−1) and (C) blank solution. Conditions: electrode, Au–modified carbon fiber detector (length: 8 cm); stationary phase, ThermoQuest Hypersil SCX (particle size 5 μm, 250 mm × 4.6 mm i.d.); Mobile phase, methanol: water (20:80 v/v) containing 1.0 mM acetate buffer (pH 4.65); detection conditions: pulsed conditions, t1 =180 ms, t2 = 180 ms. Initial potential E1(det) = +1.0 V, final potential E2(ox)= +2.0 V, flow rate, 0.5 mL·min−1.

Mentions: It is apparent that the flow rate 0.5 mL·min−1 is most suitable, because the peak height of cysteine is the highest and retention time of 7.15 min is shorter than the others (except 0.6 mL·min−1). The chromatograms in Figure 12(A–C) are comparable to a chromatogram of cysteine at bare Au, Au/CFE and blank solution. The peak height of cysteine at Au electrode (retention time 7.49 min) is smaller than that on Au/CFE (retention time 7.40 min). The Au electrode is expensive and needs a clean surface which cannot be discarded as Au/CFE. Therefore, the Au/CFE was suitable as working electrode in a flow cell-voltammetric sensor for the determination of cysteine.


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)

Chromatograms obtained using Au electrode (A) and Au/CFE (B) for cysteine (0.5 mg·L−1) and (C) blank solution. Conditions: electrode, Au–modified carbon fiber detector (length: 8 cm); stationary phase, ThermoQuest Hypersil SCX (particle size 5 μm, 250 mm × 4.6 mm i.d.); Mobile phase, methanol: water (20:80 v/v) containing 1.0 mM acetate buffer (pH 4.65); detection conditions: pulsed conditions, t1 =180 ms, t2 = 180 ms. Initial potential E1(det) = +1.0 V, final potential E2(ox)= +2.0 V, flow rate, 0.5 mL·min−1.
© Copyright Policy
Related In: Results  -  Collection

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

f12-sensors-12-03562: Chromatograms obtained using Au electrode (A) and Au/CFE (B) for cysteine (0.5 mg·L−1) and (C) blank solution. Conditions: electrode, Au–modified carbon fiber detector (length: 8 cm); stationary phase, ThermoQuest Hypersil SCX (particle size 5 μm, 250 mm × 4.6 mm i.d.); Mobile phase, methanol: water (20:80 v/v) containing 1.0 mM acetate buffer (pH 4.65); detection conditions: pulsed conditions, t1 =180 ms, t2 = 180 ms. Initial potential E1(det) = +1.0 V, final potential E2(ox)= +2.0 V, flow rate, 0.5 mL·min−1.
Mentions: It is apparent that the flow rate 0.5 mL·min−1 is most suitable, because the peak height of cysteine is the highest and retention time of 7.15 min is shorter than the others (except 0.6 mL·min−1). The chromatograms in Figure 12(A–C) are comparable to a chromatogram of cysteine at bare Au, Au/CFE and blank solution. The peak height of cysteine at Au electrode (retention time 7.49 min) is smaller than that on Au/CFE (retention time 7.40 min). The Au electrode is expensive and needs a clean surface which cannot be discarded as Au/CFE. Therefore, the Au/CFE was suitable as working electrode in a flow cell-voltammetric sensor for the determination of cysteine.

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
Related in: MedlinePlus