Ersin Demir*, Ahmet Senocak, Mouhoum Franck Tassembedo-Koubangoye, Erhan Demirbas and Hassan Y. Aboul-Enein* Pages 1 - 8 ( 8 )
Background: The total antioxidant capacity of yam food grown in southern African regions was investigated by a polyglycine-glassy carbon modified electrode. The modified electrode was fabricated using glycine solution on glassy carbon electrode by electrodeposition method. The proposed modified electrode is found to be nearly 3-fold more sensitive than the bare electrode. For the measurement of the total antioxidants of yam, differential pulse stripping voltammetry (DPSV) is employed with standard quercetin compound. Methods: The total antioxidant capacity of yam was deduced by DPSV and cyclic voltammetry (CV) methods. The basic parameters for the stripping technique such as pH, accumulation time and accumulation potential were optimized as 20 s, 200 mV and a pH of 3 Britton-Robinson (B-R) buffer solutions in 0.5 mg quercetin/L, respectively. Results: In the optimization condition, the linear working range was determined between 5.0 μg/L and 80.0 μg/L for the quercetin. The detection (LOD) and quantification (LOQ) limits of quercetin were found to be 0.39 μg/L and 1.39 μg/L on the modified electrode by DPSV, respectively. The procedure was also applied to natural yam samples and total antioxidant capacity of 0.1 kg of yam was determined as 96.15 ± 0.85 μg/L of equivalent quercetin at 95% confidence level with the relative standard deviations of 0.88%. Conclusion: Sensitive and selective voltammetric method was developed for the determination of total antioxidant capacity in yam. Moreover, the modified polyglycine-MWCNT electrode was constructed more selectively for quercetin. As a result, a simple, sensitive and rapid new voltammetric method for the determination of antioxidants has been developed using the modified electrode.
Antioxidant capacity; Yam; Differential pulse stripping voltammetry; Modified electrode.
Okan University, Department of Food Engineering, Faculty of Engineering, Istanbul, 34959, Gebze Technical University, Department of Chemistry, 41400 Gebze, Kocaeli, Okan University, Department of Food Engineering, Faculty of Engineering, Istanbul, 34959, Gebze Technical University, Department of Chemistry, 41400 Gebze, Kocaeli, Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Giza 12622