RESUMO
In contrast to the hyperactive platinum electrode, ARS modified platinum electrode presents a remarkable inertness toward adsorption and surface processes and lends it for further voltammetric applications. Measuring pyrogallol levels in samples is significant for assessing their antioxidant activity, which is crucial for understanding their potential health benefits and ability to combat oxidative stress. In addition, the excess consumption of pyrogallol can have significant negative effects on human health. A voltammetric sensor has been developed for the determination of pyrogallol using ARS modified platinum electrode. The electrode was prepared by electrodeposition of alizarin red S on a platinum electrode using cyclic voltammetry with a potential scan range of - 0.4 to 1.2 V against an Ag/AgCl quasi reference electrode for 60 cycles as optimum number of cycles. The modified electrode was characterized by CV and SEM techniques. This modified alizarin red S platinum electrode showed remarkable electrocatalytic performance and stability, resulting in a significant increase in pyrogallol oxidation current by 11.05% compared to the pyrogallol oxidative current at the unmodified platinum electrode. A well-defined oxidation peak was observed at ~ 0.40 V. The sensor exhibited a low limit of detection (LOD) of 0.28 µM and a linear standard curve covering the ranges of 1.0-40 µM and 0.01-10.0 mM pyrogallol. Extensive studies were performed to evaluate possible interferences from various organic and inorganic compounds and yielded satisfactory results that confirm the selectivity of the developed sensor for pyrogallol determination. In addition, the ARS-Pt electrode provided consistently reliable results for the accurate detection of pyrogallol in water and tomato samples.
RESUMO
Background: In contrast to the hyper-reactive platinum electrode, iodine-coated platinum electrode shows remarkable inertness toward adsorption and surface processes. For this reason, iodine-coated platinum electrode lends itself to interesting voltammetric applications. Hydrodynamic voltammetric analysis, one of the voltammetric techniques family, has many advantages over stationary voltammetric techniques inter alia the steady state current and the higher sensitivity. Objective: The present work is aimed at utilization of iodine-coated platinum rotating disk electrode for analysis of iron in spinach. Methods: The developed method is based on a voltammetric sweep at an iodine-coated rotating-disk platinum electrode. The optimized experimental parameters included a potential scan from -0.20 to 0.85 V versus Ag/AgCl/[Cl-] = 1.0 M, 50 mV/s scan rate, and a rotation rate of 1000 rpm. Results: Oxidation of iron at the iodine-coated platinum rotating disk electrode was manifested by a wave at E1/2 = +0.72 V. The limiting current was found to exhibit an excellent linearity with the concentration of iron (R2 = 0.996). The detection limit was 0.0 7 ppm. A comparative analytical study on determination of iron content in spinach samples was conducted by the voltammetric method and ICP-OES method. Application of the paired t-test to the results indicated that the null hypothesis is valid at P = 0.05. Conclusions: A sensitive and selective validated method was developed for determination of iron content in spinach. Highlights: A simple, fast, and reliable voltammetric method was developed for iron analysis in spinach. The main feature of the developed method is removing the effect of cationic interferences.
