In this work the modified iodine-coated polycrystalline platinum electrode was used to develope a voltammetric sensor for paracetamol determination in pharmaceutical formulations. The optimized experimental parameters for the determination of paracetamol were using 0.5 M H2SO4 as a supporting electrolyte with a scan rate of 50 mV/s. The anodic peak related to paracetamol oxidation was centered at about +0.60 V. The extended calibration graph was constructed between 1 ppm and 500 ppm. The anodic current showed excellent linearity with R2 = 0.9985. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.046 and 0.139 ppm, respectively, which attests to the sensitivity of the method. The investigation for the effect of potential interferences from the content of tablet matrices indicated a specific selectivity toward paracetamol and the absence of any electrochemical response toward these components. The developed method was successfully applied to analysis paracetamol in three brands of pharmaceutical formulations and the obtained results were in good agreement with the labeled values, besides that, the statistical tests indicated no significant difference at p = 0.05 with a 95 % confidence level.

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 aliathe 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 methodwas developed for iron analysis in spinach. The main feature of the developed method is removing the effect of cationic interferences.

In this work, the utilization of the modified iodine-coated polycrystalline platinum electrode as a voltammetric sensor for copper determination in pharmaceutical formulations was reported. The optimized experimental parameters for the determination of copper were using 0.1M KCl as a supporting electrolyte with a scan rate of 50 mV/s, deposition potential of - 0.2 V, and a deposition time of 2 minutes. The anodic peak related to Copper oxidation is centered at about + 0.05 V. The extended detected linear range for the developed method was between 1 ppm and 100 ppm. The anodic current showed excellent linearity with R2 = 0.9986. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.115 ppm and 0.346 ppm, respectively, which attests to the sensitivity of the method. The investigation for the effect of potential interferences from multivitamins tablet ingredients indicated a specific selectivity toward copper and the absence of any electrochemical response toward these components. The developed method was successfully applied to analyze copper and the obtained results were in good agreement with the labeled values, besides that, the statistical tests indicated no significant difference at p = 0.05 with 95 % confidence level.

Background: Despite the high reactivity of the platinum electrode, the iodine-coated platinum electrode shows obvious inertness toward adsorption and surface processes. For that, iodine-coated platinum electrodes accommodate themselves to interesting voltammetric applications. Objectives: This study reports using the modified iodine-coated polycrystalline platinum electrode as a voltammetric sensor for ascorbic acid determination in pharmaceutical formulations. Methods: The developed voltammetric method based on recording cyclic voltammograms of ascorbic acid at iodine-coated electrode The optimized experimental parameters for the determination of ascorbic acid were using 0.1 M KCl as a supporting electrolyte with a scan rate of 50mV/s. Results: The anodic peak related to ascorbic acid oxidation was centered at nearly 0.28V. An excellent and extended linear dependence of the oxidative peak current on the concentration of ascorbic acid was observed in the range 2.84x10-3 - 5.68 mM. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.0 µM and 3.01 µM, respectively, attesting to the method’s sensitivity. The investigation for the effect of potential interference from multivitamin tablet ingredients (vitamins B1, B6, B12, folic acid, citric acid, sucrose, glucose, and zinc) indicated specific selectivity toward ascorbic acid and the absence of any electrochemical response toward these components. Recovery results in the range 98.93±2.78 - 99.98±5.20 for spiked standard ascorbic acid in pharmaceutical formulations further confirmed the potential applicability of the developed method for the determination of ascorbic acid in real samples. Conclusions: The developed method was successfully applied to the analysis of ascorbic acid (vitamin C), and the obtained results were in good agreement with the labeled values; besides, the statistical tests indicated no significant difference at p=0.05 with a 95% confidence level.

An iodine-coated polycrystalline platinum electrode was applied to analysis of iron in dietary supplements. The developed method is based on scanning the potential of the iodine-coated polycrystalline platinum electrode between the hydrogen evolution limit (-0.25 V) and a potential lower than the threshold of iodine desorption from the platinum surface (ca. +0.80 V). An anodic peak centered nearly at 0.56 V is assigned to Fe(II) oxidation to Fe(III). The anodic peak current (i p ) showed an excellent linearity (R 2 = 0.995) with the concentration of Fe 2+ within a concentration range from 4-500 ppm Fe. The anodic peak current, as expected for a diffusion controlled process showed a linear relationship with the square root of the scan rate (R 2 =0.999). The limit of detection (based on S/N = 3) for the developed method is 2.34 ppm while the limit of quantitation (based on S/N = 10) is 7.8 ppm. The effect of potential interferences like calcium, magnesium, zinc, selenium, copper, manganese, chromium, molybdenum, vanadium was investigated. Silver and copper were the only ones among the investigated elements which showed resolved peaks from those of Fe (II) within the accessible potential window of the iodine-coated platinum electrode. Analysis of real samples and application of statistical tests to the results indicated the absence of systematic error in the results and the validity of the null hypothesis, i.e., there is no significant difference between the nominal values reported by the manufacturers and our results at p=0.05.