A Comparative Study on Electrochemical Determination of Vitamin C in Liver and Tomato Using Platinum and Glassy Carbon Electrodes (Original Article)

Abstract

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 mMPt; 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 andy = 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 GCEand 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.