Hamidreza Zare-mehrjardi
Abstract
In this study, the surface of the glassy carbon electrode (GCE) is modified with the nanocomposite of graphene oxide (GO)/ ionic liquid (1-Butyl-3-methylimidazolium tetrafluoroborate; [BMIM]BF4). The electrochemical behavior of ascorbic acid (AA) and dopamine (DA) at the surface of the modified glassy ...
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In this study, the surface of the glassy carbon electrode (GCE) is modified with the nanocomposite of graphene oxide (GO)/ ionic liquid (1-Butyl-3-methylimidazolium tetrafluoroborate; [BMIM]BF4). The electrochemical behavior of ascorbic acid (AA) and dopamine (DA) at the surface of the modified glassy carbon electrode was studied using the differential pulse and cyclic voltammetric methods (DPV and CV). The results show good response sensitivity to AA and DA. The acceleration of the electron transfer rate and enhancement of the electroactive surface area is obtained due to a synergistic effect in the concurrent presence of GO and [BMIM]BF4 at the surface of the electrode. The presence of GO caused to a higher specific surface of the electrode, and ionic liquid ([BMIM]BF4) increased the ion conductivity and dispersibility in the modifier layer at the surface of the GCE. These results obtained in optimum conditions, show good peak separation for AA and DA (more than 300 mV), and the sub-micromolar detection limits for them. The obtained results in this work, make the modified GCE very effective in the manufacture of simple devices for the detection of AA and DA in human urine samples.
Fatemeh Nourpishe; Ali Asghar Amiri; Ali Sheibani; Masoud Reza Shishehbore
Abstract
In this study, a simple and sensitive method was developed for pre-concentration of spirotetramat (SPT) using the ionic liquid-based dispersive liquid-liquid microextraction. After extracting of SPT into 1-butyl-3-methylimidazolium hexafluorophosphate (ionic liquid), the insecticide was injected into ...
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In this study, a simple and sensitive method was developed for pre-concentration of spirotetramat (SPT) using the ionic liquid-based dispersive liquid-liquid microextraction. After extracting of SPT into 1-butyl-3-methylimidazolium hexafluorophosphate (ionic liquid), the insecticide was injected into HPLC system for determining. Under the optimum conditions, the developed method provided a linearity in the range of 0.05–2.0 µg mL-1 with R2= 0.9987, and also enrichment factor was 250. The detection limit and relative standard deviation of the developed method were 0.01 µg mL-1 and 2.7%, respectively. The proposed method was successfully applied to the pre-concentration and determination of SPT in spiked water samples with mean recoveries 94.0-96.0%.
Arezoo Zohourtalab; Habib Razmi
Volume 5, Issue 1 , March 2018, , Pages 9-16
Abstract
A kind of ferrocene mediated enzymatic biosensor was fabricated in order to the measurement of glucose as an important biological analyte. A homogenous mixture of ferrocene including Chitosan(CS), Nafion(Nf) and an imidazolium based ionic liquid, 1-butyl-3-methyl imidazoliumhexafluorophosphate, ...
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A kind of ferrocene mediated enzymatic biosensor was fabricated in order to the measurement of glucose as an important biological analyte. A homogenous mixture of ferrocene including Chitosan(CS), Nafion(Nf) and an imidazolium based ionic liquid, 1-butyl-3-methyl imidazoliumhexafluorophosphate, [BMIM]HF6PO4, was prepared. The mentioned mixture was cast on the surface of carbon ceramic electrode and an enzymatic layer was entrapped between two layers of this mixture in order to improving the mechanical stability of the biosensor. Cyclic voltammetry and chronoamperometry were used to investigate the analytical performance of the biosensor. Remarkable deduction of interfering signals produced by AA and UA was obtained by applying a constant potential (180mV) on the human plasma for a short period of time (100min). Values of practical parameters such as sensitivity (2.73 µA mM-1cm-2), linear range (95.23–1367.5 µM) and detection limit (48 µM) were obtained by the chronoamperometric studies. The apparent Michaels-Menten constant, Km (3.52 mM) was also calculated. In order to estimate the practical accuracy and precision of the enzymatic biosensor, a test of spiked glucose solution recovery in natural plasma was done.
Sedigheh Kamran
Volume 3, Issue 2 , September 2016, , Pages 105-115
Abstract
Fe3O4 nanoparticles and their binary mixtures ([C8MIM]-Fe3O4) with 1-Octyl-3-methylimidazolium bromide were prepared and characterized as ionic liquid for using in the adsorption of phenylalanine, tryptophan, and tyrosine. The characteristics of [C8MIM]-Fe3O4 nanoparticles were investigated via ...
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Fe3O4 nanoparticles and their binary mixtures ([C8MIM]-Fe3O4) with 1-Octyl-3-methylimidazolium bromide were prepared and characterized as ionic liquid for using in the adsorption of phenylalanine, tryptophan, and tyrosine. The characteristics of [C8MIM]-Fe3O4 nanoparticles were investigated via using TEM, XRD and FTIR techniques. The pH of the point of zero charge (pHpzc) of both Fe3O4 and [C8MIM]-Fe3O4 were obtained based on the experimental curves corresponding to the immersion technique. Experimental results were obtained under optimum operational conditions of: nanoparticle amount of 0.015 g and a contact times of 5, 10, 15 minutes for tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe), respectively, when initial concentration of each amino acid was 5.0×10−4 mol L−1. The isotherm evaluations revealed that the Freundlich model attained better fits to the equilibrium data than the Dubinin-Radushkevich model. The maximum obtained adsorption capacities of Tyr, Trp and Phe were 12.74, 3.55 and 35.62 mg amino acid per gram of adsorbent, respectively. The applicability of pseudo-first order and pseudo-second order kinetic models was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. Furthermore, the adsorption processes were found endothermic. Both phenylalanine and tyrosine were desorbed from [C8MIM]-Fe3O4 nanoparticles by using NaOH aqueous solution with concentrations of 1.0 and 2.0 mol L−1, respectively. Tryptophan was completely desorbed in the presence of a mixture of 1.0 mol L−1 NaCl and 1.0 mol L−1 NaOH. The nanoparticles thus were recycled.
Sedigheh Kamran; Hossein Tavallali; Ali Azad
Volume 1, Issue 2 , September 2014, , Pages 78-86
Abstract
Fe3O4 magnetic nanoparticles modified with 1-Octyl-3-methylimidazolium bromide([C8MIM]-Fe3O4) were used for the removal of reactive red 141 (RR141) and reactive yellow 81 (RY81) as model azo dyes from aqueous solution. The mean size and the surface morphology of the nanoparticles were characterized by ...
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Fe3O4 magnetic nanoparticles modified with 1-Octyl-3-methylimidazolium bromide([C8MIM]-Fe3O4) were used for the removal of reactive red 141 (RR141) and reactive yellow 81 (RY81) as model azo dyes from aqueous solution. The mean size and the surface morphology of the nanoparticles were characterized by TEM, XRD and FTIR techniques. Adsorption studies of two dyes were performed under different experimental conditions in batch technique. The adsorption of dyes onto [C8MIM]-Fe3O4 nanoparticles was affected by the initial pH, dye concentration, adsorbent amount, contact time and temperature. Experimental results indicated that [C8MIM]-Fe3O4 nanoparticles removed more than 98%. The maximum adsorption capacity of [C8MIM]-Fe3O4 for the Langmuir model was 71.4 mg g−1 and 62.5 mg g−1 for RR141 and RY81, respectively. The isotherm evaluations revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. Adsorption processes onto [C8MIM]-Fe3O4 nanoparticles were spontaneous exothermic and endothermic for RY81 and RR141, respectively. Dyes were desorbed from nanoparticlesby NaCl solution 0.1 mol L−1 at 80 and 30 °C for RR141 and RY81, respectively.
