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Ascorbic acid, a
water-soluble vitamin, is the most common electroactive
biological compound found in most biological species. The
electrochemical oxidation of vitamin C was investigated at
GCE and Pt electrodes in various aqueous solutions in the pH
range of 1 to 5 (0.1 M KCl as a supporting electrolyte) by
CV and DPV. Experimental conditions, for CV :Scan rate of 50
mV/s, Initial potential -100 mV and Final Potential 1000 mV,
for DPV: Scan Rate 50mV/s, Pulse amplitude 50mV,Pulse period
125 ms, Initial potential -100mV and Final Potential 1000
mV. For cyclic voltammetry, Regression equation of
y=23.4611X + 13.2489 for GCE and y=5.19714X + 13.7071 Pt;
LOD of 0.0035294 mM for GCE and 0.0176 mM for Pt; LOQ of
0.025519 mM for GCE and 0.085066 mM Pt; R.S.D of %2.76% for
GCE and 4.42% for Pt. And for DPV Regression equation, y =
1.201X + 0.530393 for GCE and y = 0.0521393X + 0.506857 for
Pt, R.S.D % 0.391% for GCE and 4.969% for Pt ,LOD 0.12412 mM
for GCE and 0.22497 mM for Pt and LOQ 0.4137 mM for GCE and
0.7499 mM for Pt. The oxidation peak potential of ascorbic
acid were 270 mV and 370 mV for GCE in CV and DPV
respectively but for Pt electrode 490 mV for CV and 370 mV
for DPV (versus Ag/AgCl reference electrode). The influence
of the operational parameters like scan rate, pulse
amplitude, pulse period, concentration and pH on the
analytical signal was investigated. The method developed by
standard was applied to ascorbic acid assessment in liver
and tomato samples. The results of ascorbic acid assessment
by DPV were compared to those obtained by CV on both GCE and
Pt electrodes.
Keywords: Vitamin C, Cyclic voltammetry, Differential pulse
voltammetry, Glassy carbon electrode, Platinum electrode,
Liver, Tomato
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