Electrochemical Evaluation of the Total Antioxidant Capacity of Yam Food Samples on a Polyglycine-Glassy Carbon Modified Electrode

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 3.15-fold more sensitive than the bare electrode. For the measurement of the total antioxidants of yam, differential pulse stripping voltammetry (DPSV) was 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-glassy carbon 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.

An Electrochemical Sensor based on Electrodeposited CTAB Film on Glassy Carbon Electrode for Detection of Morphine

A simple, effective and rapid method for the electrochemical detection of morphine is described based on glassy carbon modified electrode with poly(CTAB). In this work, poly(CTAB) thin film was generated through elecropolymerization of the surfactant CTAB. The formation of nanoporous thin film of poly(CTAB) was confirmed by field emission scanning electron microscopy (FESEM) with energy dispersive spectra (EDS) and Fourier transform infrared spectroscopy (FTIR). The electrochemical behavior of morphine is explained in terms of the anodic oxidation of its tertiary amino group. The limit of detection was calculated as 0.2 μM with a good regression between concentration and peak current of morphine by using differential pulse voltammetry within the range of 50 nM to 20 μM. The poly(CTAB)/GCE based sensor shows excellent electrochemical performance for the detection of morphine and this sensing platform can be effective for the detection of similar molecules.

Simultaneous and selective electrochemical determination of hydroquinone, catechol and resorcinol at poly(1,5-diaminonaphthalene)/glassy carbon-modified electrode in different media

Electrochemical behaviors of hydroquinone, catechol and resorcinol were examined at poly(1,5-diaminonaphthalene)/glassy carbon-modified electrode by cyclic voltammetry, square wave voltammetry and chronoamperometry techniques in different media.