A sensitive cathodic stripping voltammetric method is developed for determination of lead(II), wi... more A sensitive cathodic stripping voltammetric method is developed for determination of lead(II), with adsorptive collection of complexes with Pyrogallol red (PGR) on to a hanging mercury drop electrode. After accumulation of the complex at (/0.80 V vs. Ag/AgCl reference electrode, the potential is scanned in a negative direction from (/0.20 to (/ 0.50 V with differential pulse method. Then the reduction peak current for the lead(II) Á/PGR complex is measured at (/ 0.39 V. The influence of reagent and instrumental variables was completely studied by factorial design analysis. The optimum analytical conditions for the determination of lead(II) were established. Under optimum conditions, lead(II) determined in the range of 0.1 Á/30.0 ng ml (1 with a limit of detection of 0.06 ng ml (1. The method is successfully applied to determination of lead(II) in water sample.
In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) an... more In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) and Cu(II)Pb(II)Cd(II) using adsorptive cathodic stripping voltammetry are described. The method is based on accumulation of these metal ions on mercury electrode using xylenol orange ...
In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) an... more In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) and Cu(II)Pb(II)Cd(II) using adsorptive cathodic stripping voltammetry are described. The method is based on accumulation of these metal ions on mercury electrode using xylenol orange ...
Journal of Chemical Technology & Biotechnology, 2013
A b s t r a c t The electrocatalytic oxidation of cysteine on multi-wall carbon nanotubes glassy ... more A b s t r a c t The electrocatalytic oxidation of cysteine on multi-wall carbon nanotubes glassy carbon electrode (MWCNTGCE) in phosphate buffer solution in pH (4.0) has been characterized using cyclic voltammetry, chronoamperometry and differential pulse voltammetry. The results showed that the catalytic current of 1,5bis(3,4-dihydroxy phenyl)penta-1,4-dien-3-one (BPO) depended on the concentration of cysteine. Although cysteine itself showed a very poor electrochemical response at the glassy carbon electrode, the response could be greatly enhanced by using BPO as a mediator, which enabled a sensitive determination of cysteine. The kinetics parameters of this process were calculated, the apparent catalytic rate constant (k΄h) and electron transfer () were 867 M -1 s -1 and 0.57 respectively. The differential pulse voltammetry response of the modified MWCNTGCE was linear against the concentration of cysteine in the range 0.5 to 30 μM the limit of detection was found to be 0.17μM.
Abstract The present paper reports using 5-(5-chloro-2,4-dihydroxyphenyl)imidazo[4,5- d ] [1,3]th... more Abstract The present paper reports using 5-(5-chloro-2,4-dihydroxyphenyl)imidazo[4,5- d ] [1,3]thiazin-7(3 H )-one (CIT) and different characterized nano-materials (nano particles based on silica (MCM-41)) and carbon (reduced graphene oxide (RGO), carbon Nano-tubes (CNT) and the mixture of them (CNT/RGO)) in the carbon pate electrode (CPE) structure as new platforms for hydrazine determination. The main purpose of this paper is investigation of effect of silica and carbon nanomaterials on the electrochemical behaviour of the various designed sensors (CIT/MCM41/CPE, CIT/RGO/CNT/CPE, CIT/RGO/CPE and CIT/CNT/CPE) for hydrazine analysis. Under the optimum conditions, some kinetic parameters of modifier such as electron transfer coefficient ( α ) and heterogeneous rate constant ( k ) for hydrazine were obtained. The observations revealed that using nanomaterials of MCM-41, RGO, CNT and RGO/CNT has a key role in decreasing oxidation potential and increasing oxidation peak currents, obtaining wider linear range and lower detection limit. The results indicated that CIT/MCM41/CPE sensor possess two linear ranges (0.01–0.032 μM and 1.0–200 μM) and a lower detection limit (0.0033 μM based on 3S b /m) than other fabricated sensors. The designed sensor was used for simultaneous determination of hydrazine and phenol. The obtained differential pulse voltammograms indicated overlapping and to solve this problem, net analyte signal (NAS) was used.
A mefenamic acid sensor was prepared by the modification of a glassy carbon electrode (GCE) with ... more A mefenamic acid sensor was prepared by the modification of a glassy carbon electrode (GCE) with graphene nano-sheets (Gr) and multi wall carbon nanotubes (MWCNT). The designed sensor (MWCNT/Gr/GCE) indicated an electrocatalytic behaviour when applied for mefenamic acid (MFA) oxidation due to good conductivity, low electron transfer resistance and catalytic effect. The suggested sensor revealed a lower overvoltage and enhanced current compared with bare GCE for the oxidation of MFA. The observations indicated that the oxidation potential of MFA is decreased more than 200 mV using the designed sensor. The percentages of MWCNTs and Gr nano materials, and pH solution were optimized. Under the optimum conditions, some kinetic parameters, such as surface coverage in a 0.5 mM [Fe(CN) 6 ] 3-/4solution was obtained by cyclic voltammetric method. The diffusion coefficient of MFA (D) was calculated to be 2.88×10-6 cm 2 s-1 by chronoamperometeric technique. The MWCNT/Gr/GCE sensor exhibited a linear dynamic range for MFA (2-100 µM) with a detection limit of 0.66 µM by differential pulse voltammetry (DPV) technique. This sensor revealed a suitable applicability for determination of MFA in real samples (drug samples and serum solutions).
Water pollution control and the development of clean technologies for water, air and soil treatme... more Water pollution control and the development of clean technologies for water, air and soil treatments comprise one of the most important challenges for modern society. Ozone is known as a strong and clean oxidizing agent that can be used for water and wastewater treatment. In this research, a novel Ti/TiHx/SnO2-Sb2O5-NiO-CNT modified titanium electrode containing carbon nanotubes (CNT) was fabricated for in-situ ozone generation. The electrode was characterized using SEM, XRD and LSV techniques. CNT presence caused an increase in ozone generation efficiency leading to the higher concentrations of dissolved ozone in water compared to the recently reported researchers. Ozone generation at the surface of the electrode was determined using the standard indigo method. Electrochemical ozone was further used in degradation of C.I. Reactive red 195 (RR 195). It was found that the modified electrode could degrade 96% of RR 195 from initial concentration of 300 mg∙L-1 in 30 min under current d...
The electrochemical behavior of ascorbic acid and folic acid upon their interaction with albumin ... more The electrochemical behavior of ascorbic acid and folic acid upon their interaction with albumin is investigated using electrochemical, chemometric and docking studies.
Due to the biological effects of phenolic acid components, polyphenol-rich foods are a significan... more Due to the biological effects of phenolic acid components, polyphenol-rich foods are a significant part of human and animal diets. In this study, the acidity constants of caffeic acid (3,4-dihydroxycinnamic acid) in binary mixtures of ethanol-water were determined spectrophotometrically using the introduced net analyte signal (NAS) algorithm and an ab initio quantum mechanical method. The NAS is an efficient chemometric algorithm for analysis of acid-base equilibrium systems by a spectrophotometric method. At different pH values, the distribution of acid species is obtained from an absorption data matrix and this procedure enabled the pK a of caffeic acid to be obtained alternatively. The results showed that pK a1 (4.
A sensitive cathodic stripping voltammetric method is developed for determination of lead(II), wi... more A sensitive cathodic stripping voltammetric method is developed for determination of lead(II), with adsorptive collection of complexes with Pyrogallol red (PGR) on to a hanging mercury drop electrode. After accumulation of the complex at (/0.80 V vs. Ag/AgCl reference electrode, the potential is scanned in a negative direction from (/0.20 to (/ 0.50 V with differential pulse method. Then the reduction peak current for the lead(II) Á/PGR complex is measured at (/ 0.39 V. The influence of reagent and instrumental variables was completely studied by factorial design analysis. The optimum analytical conditions for the determination of lead(II) were established. Under optimum conditions, lead(II) determined in the range of 0.1 Á/30.0 ng ml (1 with a limit of detection of 0.06 ng ml (1. The method is successfully applied to determination of lead(II) in water sample.
In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) an... more In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) and Cu(II)Pb(II)Cd(II) using adsorptive cathodic stripping voltammetry are described. The method is based on accumulation of these metal ions on mercury electrode using xylenol orange ...
In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) an... more In this work, simultaneous determination of two groups of elements consisting of Pb(II)Cd(II) and Cu(II)Pb(II)Cd(II) using adsorptive cathodic stripping voltammetry are described. The method is based on accumulation of these metal ions on mercury electrode using xylenol orange ...
Journal of Chemical Technology & Biotechnology, 2013
A b s t r a c t The electrocatalytic oxidation of cysteine on multi-wall carbon nanotubes glassy ... more A b s t r a c t The electrocatalytic oxidation of cysteine on multi-wall carbon nanotubes glassy carbon electrode (MWCNTGCE) in phosphate buffer solution in pH (4.0) has been characterized using cyclic voltammetry, chronoamperometry and differential pulse voltammetry. The results showed that the catalytic current of 1,5bis(3,4-dihydroxy phenyl)penta-1,4-dien-3-one (BPO) depended on the concentration of cysteine. Although cysteine itself showed a very poor electrochemical response at the glassy carbon electrode, the response could be greatly enhanced by using BPO as a mediator, which enabled a sensitive determination of cysteine. The kinetics parameters of this process were calculated, the apparent catalytic rate constant (k΄h) and electron transfer () were 867 M -1 s -1 and 0.57 respectively. The differential pulse voltammetry response of the modified MWCNTGCE was linear against the concentration of cysteine in the range 0.5 to 30 μM the limit of detection was found to be 0.17μM.
Abstract The present paper reports using 5-(5-chloro-2,4-dihydroxyphenyl)imidazo[4,5- d ] [1,3]th... more Abstract The present paper reports using 5-(5-chloro-2,4-dihydroxyphenyl)imidazo[4,5- d ] [1,3]thiazin-7(3 H )-one (CIT) and different characterized nano-materials (nano particles based on silica (MCM-41)) and carbon (reduced graphene oxide (RGO), carbon Nano-tubes (CNT) and the mixture of them (CNT/RGO)) in the carbon pate electrode (CPE) structure as new platforms for hydrazine determination. The main purpose of this paper is investigation of effect of silica and carbon nanomaterials on the electrochemical behaviour of the various designed sensors (CIT/MCM41/CPE, CIT/RGO/CNT/CPE, CIT/RGO/CPE and CIT/CNT/CPE) for hydrazine analysis. Under the optimum conditions, some kinetic parameters of modifier such as electron transfer coefficient ( α ) and heterogeneous rate constant ( k ) for hydrazine were obtained. The observations revealed that using nanomaterials of MCM-41, RGO, CNT and RGO/CNT has a key role in decreasing oxidation potential and increasing oxidation peak currents, obtaining wider linear range and lower detection limit. The results indicated that CIT/MCM41/CPE sensor possess two linear ranges (0.01–0.032 μM and 1.0–200 μM) and a lower detection limit (0.0033 μM based on 3S b /m) than other fabricated sensors. The designed sensor was used for simultaneous determination of hydrazine and phenol. The obtained differential pulse voltammograms indicated overlapping and to solve this problem, net analyte signal (NAS) was used.
A mefenamic acid sensor was prepared by the modification of a glassy carbon electrode (GCE) with ... more A mefenamic acid sensor was prepared by the modification of a glassy carbon electrode (GCE) with graphene nano-sheets (Gr) and multi wall carbon nanotubes (MWCNT). The designed sensor (MWCNT/Gr/GCE) indicated an electrocatalytic behaviour when applied for mefenamic acid (MFA) oxidation due to good conductivity, low electron transfer resistance and catalytic effect. The suggested sensor revealed a lower overvoltage and enhanced current compared with bare GCE for the oxidation of MFA. The observations indicated that the oxidation potential of MFA is decreased more than 200 mV using the designed sensor. The percentages of MWCNTs and Gr nano materials, and pH solution were optimized. Under the optimum conditions, some kinetic parameters, such as surface coverage in a 0.5 mM [Fe(CN) 6 ] 3-/4solution was obtained by cyclic voltammetric method. The diffusion coefficient of MFA (D) was calculated to be 2.88×10-6 cm 2 s-1 by chronoamperometeric technique. The MWCNT/Gr/GCE sensor exhibited a linear dynamic range for MFA (2-100 µM) with a detection limit of 0.66 µM by differential pulse voltammetry (DPV) technique. This sensor revealed a suitable applicability for determination of MFA in real samples (drug samples and serum solutions).
Water pollution control and the development of clean technologies for water, air and soil treatme... more Water pollution control and the development of clean technologies for water, air and soil treatments comprise one of the most important challenges for modern society. Ozone is known as a strong and clean oxidizing agent that can be used for water and wastewater treatment. In this research, a novel Ti/TiHx/SnO2-Sb2O5-NiO-CNT modified titanium electrode containing carbon nanotubes (CNT) was fabricated for in-situ ozone generation. The electrode was characterized using SEM, XRD and LSV techniques. CNT presence caused an increase in ozone generation efficiency leading to the higher concentrations of dissolved ozone in water compared to the recently reported researchers. Ozone generation at the surface of the electrode was determined using the standard indigo method. Electrochemical ozone was further used in degradation of C.I. Reactive red 195 (RR 195). It was found that the modified electrode could degrade 96% of RR 195 from initial concentration of 300 mg∙L-1 in 30 min under current d...
The electrochemical behavior of ascorbic acid and folic acid upon their interaction with albumin ... more The electrochemical behavior of ascorbic acid and folic acid upon their interaction with albumin is investigated using electrochemical, chemometric and docking studies.
Due to the biological effects of phenolic acid components, polyphenol-rich foods are a significan... more Due to the biological effects of phenolic acid components, polyphenol-rich foods are a significant part of human and animal diets. In this study, the acidity constants of caffeic acid (3,4-dihydroxycinnamic acid) in binary mixtures of ethanol-water were determined spectrophotometrically using the introduced net analyte signal (NAS) algorithm and an ab initio quantum mechanical method. The NAS is an efficient chemometric algorithm for analysis of acid-base equilibrium systems by a spectrophotometric method. At different pH values, the distribution of acid species is obtained from an absorption data matrix and this procedure enabled the pK a of caffeic acid to be obtained alternatively. The results showed that pK a1 (4.
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