Analytical chemistry
Ghobad Mansouri; Mohammd Bagher Gholivand; Zarrin Eshaghi
Abstract
A single-use electrochemical sensor using ionic liquid mediated hollow fiber-graphite working electrode was fabricated for the first time. The screening tool was developed by coupling this electrode with differential pulse voltammetry (DPV) for in-situ pre-concentration and determination of Zn(II) and ...
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A single-use electrochemical sensor using ionic liquid mediated hollow fiber-graphite working electrode was fabricated for the first time. The screening tool was developed by coupling this electrode with differential pulse voltammetry (DPV) for in-situ pre-concentration and determination of Zn(II) and Cu(II). In our plot, porous polypropylene hollow fiber membrane was divided into pieces of 2 cm, then fiber's lumen and pores were satiated with homogeneous mixture of reduced graphene oxide (rGO) and three types used ionic liquids:(1-ethyl-3-methylimidazolium tetrafuoroborate), (1-butyl-3-methylimidazoliumhexafluorophosphate) and (1-butyl-2,3-dimethylimidazolium hexafluorophosphate) individually. Thereafter, a pencil graphite rod was placed inside the fiber. Fabricated sensors were used for single-step simultaneous purification and determination of Zn(II) and Cu(II) ions from water samples. The response surface method (RSM) was used as the basis of the design and analysis of the experiments. Parameters that were mostly important in the separation part of the study, such as: molar mass of ionic liquids, amount of nanoparticle and sonication time have been investigated. Analysis of variance (ANOVA) and RSM contour plots were presented for effect of all factors (input parameters) on the maximum current of differential pulse voltammetry (DPV) peaks (output responses). The results disclosed that the metal removal was impressed by the molar mass of ionic liquids, amount of nanoparticle and sonication time respectively. The efficiency specifications of this procedure were evaluated by calculating precision and response linearity. Under the optimal experimental conditions linear concentration ranges of 0.9–550µgL-1 and 0.7–500 µgL-1 were obtained for Zn(II) and Cu(II) ions respectively. The reported limit of detection for Zn(II) and Cu(II) were 0.27 and 0.21µgL-1 with relative standard deviations (RSD) 3.2%, and 4.4%, respectively. In addition, this sensor was successfully applied to real water samples.
Analytical chemistry
Masoumeh Taei; Hossein Salavati; Masoud Fouladgar; Elmira Abbaszadeha
Abstract
The ZnCrFeO4 nanoparticles were synthesized as antiferromagnetic material using sol-gel method. The X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) certified that ZnCrFeO4 nanoparticles have single-phase cubic structure with a range of 50–100 nm in size. A facile and ...
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The ZnCrFeO4 nanoparticles were synthesized as antiferromagnetic material using sol-gel method. The X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) certified that ZnCrFeO4 nanoparticles have single-phase cubic structure with a range of 50–100 nm in size. A facile and sensitive analytical method was developed for simultaneous determination of sunset yellow and tartrazine based on ZnCrFeO4 modified paste electrode. The oxidation responses of sunset yellow and tartrazine are improved extremely at the modified carbon paste electrode (ZnCrFeO4/CPE), exhibiting two well-defined anodic peaks at + 0.70V and +0.99 V vs Ag/AgCl, respectively. The oxidation reactions were controlled by diffusion step for tartrazine and adsorption step for sunset yellow. Simultaneous determination of these dyes indicated wide linear ranges from 0.07 to 47.5, and 0.05 to 19.0 μmol L−1 with detection limits of 2.0 and 10.0 nmol L−1 for sunset yellow and tartrazine, respectively. The results of real samples analyses affirmed that ZnCrFeO4/CPE possess remarkable potential to determine simultaneously sunset yellow and tartrazine in soft drinks samples.
Analytical chemistry
Roghiyeh Pourghobadi; Mohammad Reza Baezzat
Abstract
The present study examines a new dopamine sensor based on Alumina nanoparticles modified carbon paste electrode (Al2O3NPsCPE). Moreover, the present study focuses on the electrochemical act of the Al2O3NPsCPE for the detection of dopamine by cyclic voltammetry (CV) and differential pulse voltammetry ...
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The present study examines a new dopamine sensor based on Alumina nanoparticles modified carbon paste electrode (Al2O3NPsCPE). Moreover, the present study focuses on the electrochemical act of the Al2O3NPsCPE for the detection of dopamine by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). There is also a focus on the specification of the prepared modified electrode by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM), and there is a discussion on the influence of some experimental variables such as carbon paste composition, laboring solution pH, scan rate and possible interferences. The present study obtained a well-defined redox peak of dopamine (DA) on the Nano- Alumina/CPE at Epa=173mV and Epc=112mV, respectively. The obtained response of the sensor was linear under the optimal conditions of the catalytic peak current, in the range of 8.0-330.0 µM, and the detection limit was 2.1 µM (S/N=3) for dopamine. The proposed sensor exhibited a high sensitivity, an excellent reproducibility, good selectivity, and it was successfully used in the determination of dopamine injection samples.
Analytical chemistry
Fatemeh Moeinpour; Zarrin Eshaghi
Volume 7, Issue 2, pp. 90-159, Serial No. 23 , April 2019, , Pages 126-138
Abstract
The objective of this study is to design a simple, fast, sensitive and single-use electrode with the simultaneous capability of preconcentration and measuring, for application in a three-electrode voltammetry system to identify and measure the heavy metal cadmium. The design process of this sensor consists ...
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The objective of this study is to design a simple, fast, sensitive and single-use electrode with the simultaneous capability of preconcentration and measuring, for application in a three-electrode voltammetry system to identify and measure the heavy metal cadmium. The design process of this sensor consists of several stages. The polyurethane foam and multi walled carbon nanotubes nanoparticles were functionalized and the new nanocomposite was synthesized that with the help of an organic solvent, established on the pencil graphite electrode that was covered with hollow fiber. In this work, for the first time, the organic solvent was employed instead of ionic liquid. The designed sensor was used to detect and measure heavy metal cadmium through differential pulse voltammetry technique, which appearance of a sharp peak at -0.82 V indicates the presence of cadmium. It was found that the presence of air molecules as the analyte carrier (between hollow fiber cavities and in fixed nanocomposite on the graphite) instead of organic solvents or ionic liquids was desirable. All the synthesis stages of nanocomposite were analyzed by infrared spectroscopy. Finally, the nanocomposite morphology was obtained with a Scanning Electron Microscope. A calibration curve was drawn and linear response with a range of 2.39 to 47.6 µM was plotted. The LOD of the designed sensor was 0.399 µM for cadmium. The mentioned sensor was used to recognize and analyte measurement in real biological samples of urine, nail, and wastewater of the laboratory.
Analytical chemistry
Hamid Reza Zare-Mehrjardi
Volume 6, Issue 3, pp. 218-324, Serial No. 20 , July 2018, , Pages 300-311
Abstract
In this paper, the carbon paste electrode (CPE) is modified using an ionic liquid (1-Butyl-3-methylimidazolium tetrafluoroborate, [BMIM]BF4) and the cis-dioxo-bis[3-methoxy-2,2-dimethylpropanediamine] molybdenum(VI) complex (cis-[Mo(O)2L]). In order to study of the electrochemical behavior of ascorbic ...
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In this paper, the carbon paste electrode (CPE) is modified using an ionic liquid (1-Butyl-3-methylimidazolium tetrafluoroborate, [BMIM]BF4) and the cis-dioxo-bis[3-methoxy-2,2-dimethylpropanediamine] molybdenum(VI) complex (cis-[Mo(O)2L]). In order to study of the electrochemical behavior of ascorbic acid (AA) and dopamine (DA) at the surface of the prepared CPEs, the differential pulse and cyclic voltammetric methods (DPV and CV) were used. The percent of the [BMIM]BF4 in the matrix of the modified CPE is optimized, and then the effect of the pH of the buffered solution on the electrode response and the resolution between the anodic peaks of AA and DA is studied by CV and DPV. These results reveal that by application of the modified CPE a peak resolution about 325mV is obtained for AA and DA and the linear range for AA and DA in buffered solutions of pH 5.0 is acquired in the range from 5.0×10−7 to 1.0×10−3 M. The respective limits of detection (S/N = 3) were 1×10−7 M and 2×10−7 M for DA and AA, respectively. Surface regeneration and the very easy preparation of the modified CPE together with the very good peak resolution and sub-micromolar detection limits designate the prepared CPE in this work appropriate for simultaneous voltammetric determination of DA and AA.
Analytical chemistry
Fatemeh Sabermahani; Nosrat Madadi Mahani; Neda Pourgholamrezazadeh
Volume 6, Issue 2, pp. 109-217, Serial No. 19 , April 2018, , Pages 148-159
Abstract
In this work, a low-cost activated carbon as well as non-hazardous material, with high adsorption capacity, was prepared from Melia azedarach fruit (MF) by ZnCl2 activation for the removal of Pb(II) toxic metal from aqueous solutions. The microstructure of the activated carbon was observed by Scanning ...
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In this work, a low-cost activated carbon as well as non-hazardous material, with high adsorption capacity, was prepared from Melia azedarach fruit (MF) by ZnCl2 activation for the removal of Pb(II) toxic metal from aqueous solutions. The microstructure of the activated carbon was observed by Scanning Electron Microscopy (SEM). Batch experiments have been performed as a function of pH, contact time, dose of sorbent, initial Pb(II) concentration, temperature and strength ionic. It was found that the adsorption process was very quick and the equilibrium attained within 10 min. The maximum adsorption capacity for Pb(II) using Langmuir isotherm was 111.11 mg g-1. Thermodynamic study indicated that the Pb(II) adsorption was feasible, spontaneous, and endothermic. The results show that the produced activated carbon from Melia azedarach fruit is an efficient and cost-effective adsorbent for removing Pb(II).
Analytical chemistry
Shaghayegh Mohebi; Ali Mazloomifar
Volume 6, Issue 1, pp. 1-108, Serial No. 18 , January 2018, , Pages 8-18
Abstract
A novel, rapid, simple and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high performance liquid chromatography-ultra violet detection (HPLC-UV) was used to determine acrylamide in potato chips. The derivation ...
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A novel, rapid, simple and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high performance liquid chromatography-ultra violet detection (HPLC-UV) was used to determine acrylamide in potato chips. The derivation of the acrylamide happened in the presence of KBr, KBrO3, H2SO4. Based on studies, 1-undecanol was selected as the extraction solvent. The factors affecting the extraction efficiency of DLLME-SFO such as the volume of the extraction solvent, kind and volume of the disperser solvent, effect of concentration of KBr, KBrO3, H2SO4 and time of centrifuge, time of derivative and extraction time were investigated and the optimal extraction conditions were estimated. Under the optimum conditions (extraction solvent: 150µl 1-undecanol;disperser solvent:1000 µl acetone; concentration of KBr, KBrO3:10 ppb; concentration of H2SO4 0.001 mol/l; extraction time: 3min), calibration curve is linear in the range of 0.5-15 ppb and correlation of determination (R2) is 0.993.The method was successfully applied for the determination of acrylamide in the actual potato chips.
Analytical chemistry
Mohammad Rezaiati; Farhad Salimi; Changiz Karami
Volume 5, Issue 4, pp. 364-493, Serial No. 17 , October 2017, , Pages 397-406
Abstract
Chromium is one of the hazardous pollutants in industrial effluents. In this study, a new nano-boehmite modified with sodium dodecyl sulphate is developed for preconcentration trace amounts of chromium ions as a prior step to its determination by flame atomic absorption spectrometry. We investigated ...
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Chromium is one of the hazardous pollutants in industrial effluents. In this study, a new nano-boehmite modified with sodium dodecyl sulphate is developed for preconcentration trace amounts of chromium ions as a prior step to its determination by flame atomic absorption spectrometry. We investigated the effect of various parameters on the recovery of the analyte ions, including pH of sample solution, amount of sorbent, sample volume on extraction efficiency of the chromium ions. Under the best experimental conditions, the calibration curve was linear in the range of 1.0 -700.0 ng.mL-1 of chromium with R2 = 0.997. Detection limit was 0.6 ng.mL-1 in the original solution (3Sb/m) and the relative standard deviation for seven replicate determination of 0.5 µg.mL-1 chromium was ±2.4%. The developed method was successfully applied to the extraction and determination of chromium in water and food samples with satisfactory results.
Analytical chemistry
Rouhollah Heydari; Farzaneh Bastami; Mohammad Hosseini; Mohammad Alimoradi
Volume 5, Issue 3, pp. 237-363, Serial No. 16 , July 2017, , Pages 242-251
Abstract
In this study, a simple and low-cost method was developed for extraction and pre-concentration of brilliant blue(BB) and Tropaeolin O(TO) in food samples using cloud point extraction (CPE) prior to spectrophotometric determination. The effects of main factors such as pH, surfactant and salt concentrations, ...
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In this study, a simple and low-cost method was developed for extraction and pre-concentration of brilliant blue(BB) and Tropaeolin O(TO) in food samples using cloud point extraction (CPE) prior to spectrophotometric determination. The effects of main factors such as pH, surfactant and salt concentrations, incubation time and temperature on the cloud point extraction of both dyes were investigated and optimized. Linear range of calibration curves were obtained in the range of 50–4000 ng mL−1 for BB and 50–5000 ng mL−1 for TO under the optimum conditions. The limit of detection values for BB and TO were 10 and 20ng mL−1, respectively. The relative standard deviation (RSD) values of both dyes for repeated measurments (n=6) were less than 2.2 %. The obtained results demonstrate that the proposed method can be applied satisfactorily to determine these dyes in different food samples.
Analytical chemistry
Parveen Rajjak Shaikh; Isak Rajjak Shaikh; Arjun Bapurao Bhosle
Volume 5, Issue 3, pp. 237-363, Serial No. 16 , July 2017, , Pages 315-337
Abstract
The physico-chemical properties of water and sediments therein were analyzed for assessing the suitability of Siddheshwar dam (India) waters for irrigation purpose. The physical parameters include total dissolved solids and electrical conductivity. The chemical parameters studied include pH, free carbon ...
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The physico-chemical properties of water and sediments therein were analyzed for assessing the suitability of Siddheshwar dam (India) waters for irrigation purpose. The physical parameters include total dissolved solids and electrical conductivity. The chemical parameters studied include pH, free carbon dioxide, total hardness, calcium hardness, magnesium hardness, phenolphthalein alkalinity, total alkalinity, biochemical oxygen demand and salinity. The present research was undertaken to monitor the irrigational suitability of this water body over the period of June 2009 to May 2010 by Sodium Absorption Ration (SAR), Magnesium Ratio (MR), Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP), Residual Sodium Bicarbonate (RSBC), Kelly’s Ratio (KR) and Permeability Index (PI) parameters. The UV-Spectrophotometer determined the concentrations of heavy metals such as iron, zinc, chromium and manganese. The sediments’ physico-chemical characteristics like temperature, conductivity, pH, % carbon, organic matter and phosphate have been detected by using standard methods. It is observed that the sediments are in a complex milieu with the overlying water in the aquatic ecosystem and they affect water chemistry and get affected by it. The water quality is found good and it is therefore safe for irrigation.
Analytical chemistry
Ahmadreza Amraei; Ali Niazi; Mohammad Alimoradi
Volume 5, Issue 2, pp. 121-236, Serial No. 15 , April 2017, , Pages 207-216
Abstract
Naphthol isomers were simultaneously and spectrophotometrically determined in wastewater, using a model based on net analyte signal (NAS). The calibration method used is a variation of the original hybrid linear analysis method as proposed by Goicoechea and Olivieri (HLA/GO). Owing to spectral interferences, ...
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Naphthol isomers were simultaneously and spectrophotometrically determined in wastewater, using a model based on net analyte signal (NAS). The calibration method used is a variation of the original hybrid linear analysis method as proposed by Goicoechea and Olivieri (HLA/GO). Owing to spectral interferences, the simultaneous determination of mixtures of naphthol isomers, using a spectrophotometric method, is difficult. A rapid and powerful method was used for wavelength selection in the modeling step, based on the minimization of the error indicator (EI), which was estimated as a function of the moving spectral region. The calculation of the net analytical signal using a modified HLA/GO method allows us to determine several figures of merit, as selectivity, sensitivity, analytical sensitivity and limit of detection of the proposed multivariate calibration. The limit of detection (LOD) for 1 and 2-naphthol, were 0.04 and 0.06 (µg/mL) respectively. The proposed model was tested in the analysis of wastewater samples, without previous sample preparation steps, obtaining recovery values between 98 and 104.00%, for 1-naphthol and between 97.00 and 103.00%, for 2-naphthol.
Analytical chemistry
Banafsheh Norouzi
Volume 5, Issue 1, pp. 1-120, Serial No. 14 , January 2017, , Pages 42-51
Abstract
A sodium dodecyl sulfate modified carbon paste electrode (SDS/CPE) was developed in this work based on the surface modification method. The modified electrode was prepared by immersing SDS/CPE in a nickel nitrate solution. This electrode showed a strong accumulation ability toward nickel ions. Then modified ...
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A sodium dodecyl sulfate modified carbon paste electrode (SDS/CPE) was developed in this work based on the surface modification method. The modified electrode was prepared by immersing SDS/CPE in a nickel nitrate solution. This electrode showed a strong accumulation ability toward nickel ions. Then modified electrode was conditioned by potential recycling in a potential range of 0.2–0.8 V (vs. Ag/AgCl/KCl) by cyclic voltammetry in alkaline medium. The results showed that the Ni/SDS on the electrode behaves as an efficient catalyst for the electrooxidation of methanol in alkaline medium via Ni (III) species formed on the electrode. Moreover, the effects of various parameters such as SDS concentration, methanol concentration, NaOH concentration and nickel nitrate concentration on the electrooxidation of methanol have also been investigated.
Analytical chemistry
Mehdi Nekoei
Volume 5, Issue 1, pp. 1-120, Serial No. 14 , January 2017, , Pages 79-98
Abstract
In this paper, the quantitative structure activity-relationship (QSAR) of the CCR2b receptor inhibitors was scrutinized. Firstly, the molecular descriptors were calculated using the Dragon package. Then, the stepwise multiple linear regressions (SW-MLR) and the genetic algorithm multiple linear regressions ...
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In this paper, the quantitative structure activity-relationship (QSAR) of the CCR2b receptor inhibitors was scrutinized. Firstly, the molecular descriptors were calculated using the Dragon package. Then, the stepwise multiple linear regressions (SW-MLR) and the genetic algorithm multiple linear regressions (GA-MLR) variable selection methods were subsequently employed to select and implement the prominent descriptors having the most significant contributions to the activities of the molecules. A combined data set including numerical values of inhibition activity data (IC50) of 103 CCR2b receptor derivatives was adopted for our simulations. This study revealed that both SW-MLR and GA-MLR methods consisted of six molecular descriptors. The adopted descriptors belong to topological, charge, RDF and atom-centered fragments classes. A comparison of results by the two methodologies indicated the superiority of GA-MLR over the SW-MLR method. The authenticity of the proposed model (GA-MLR) was further confirmed using the cross-validation, validation through an external test set and Y-randomization.
Analytical chemistry
Nahid Tavakkoli; Nasrin Soltani; Arezo Afsharpour
Volume 4, Issue 4, pp. 359-490, Serial No. 13 , October 2016, , Pages 414-432
Abstract
In this article electrochemical determination of captopril at the surface of the platinum coated nanoporous gold film (PtNPGF) electrode is reported using the cyclic voltammetry and amperometry. For the preparation of PtNPGF, the surface of NPGF electrode was covered with Cu layer using underpotential ...
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In this article electrochemical determination of captopril at the surface of the platinum coated nanoporous gold film (PtNPGF) electrode is reported using the cyclic voltammetry and amperometry. For the preparation of PtNPGF, the surface of NPGF electrode was covered with Cu layer using underpotential electrochemical deposition (UPD).Afterward, the copper layer is replaced with platinum ions via a spontaneous redox reaction to have a uniform Ptoverlayer. Under the optimized conditions, the amperometry peak current of captopril increased linearly with captopril concentration in the ranges of 4.70×10-8 to 4.57×10-5mol L−1. The detection limit of captopril was 1.2×10-8mol L−1. The results show a very good precision (R.S.D < 2.4%), suitable selectivity and very stable response for captopril. The proposed sensor was successfully applied for the determination of captopril in the urine samples of patient human.
Analytical chemistry
Sohrab Ershad; Noshin Safarzadeh; Hamzeh Akhondi-Yamchi
Volume 4, Issue 3, pp. 236-358, Serial No. 12 , July 2016, , Pages 256-264
Abstract
A novel chemically modified electrode containing Prussian blue complex was achieved on the surface of glass carbon electrode by sol-gel technique. The electrochemical behavior of modified electrode was characterized by cyclic voltammetry in detail. The film electrode obtained was very stable and exhibited ...
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A novel chemically modified electrode containing Prussian blue complex was achieved on the surface of glass carbon electrode by sol-gel technique. The electrochemical behavior of modified electrode was characterized by cyclic voltammetry in detail. The film electrode obtained was very stable and exhibited electrocatalytic response for oxidation of nitrite. Results showed at bare GC electrode, a small oxidation peak current was observed at about 740 mV and a well-formed sharp catalytic oxidation peak at about 600 mV was observed at Prussian blue complex modified electrode. The transfer coefficient (α) for electrocatalytic oxidation of nitrite and the diffusion coefficient of this substance under the experimental conditions were also investigated.
Analytical chemistry
Meysam Sadeghi; Sina Yekta
Volume 4, Issue 1, pp. 1-132, Serial No. 10 , January 2016, , Pages 21-41
Abstract
In this work, the practicality of catalytic surfaces of nano-structured Co3O4 and MnCo2O4 for the adsorption and neutralization reactions of dimethyl methyl phosphonate (DMMP) as an toxic agricultural organo-phosphorous pesticide has been investigated. The Co3O4 and MnCo2O4 NPs have been successfully ...
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In this work, the practicality of catalytic surfaces of nano-structured Co3O4 and MnCo2O4 for the adsorption and neutralization reactions of dimethyl methyl phosphonate (DMMP) as an toxic agricultural organo-phosphorous pesticide has been investigated. The Co3O4 and MnCo2O4 NPs have been successfully prepared by precipitation method using cobalt nitrate and manganese nitrate as the precursors and then characterized by SEM-EDX and XRD. The application of the synthesized nanoparticles as solid catalysts for the adsorption and neutralization of dimethyl methyl phosphonate (DMMP) was assayed in different solvents and monitored by 31PNMR and IR analyses. The experimental results have shown that 39%, 47% and 62% of DMMP have been adsorbed on the surface of Co3O4 nanoparticles in isopropanol, chloroform and decane solvents after 5 h, respectively. While, higher amounts (80%, 92% and 100%) were removed in the same solvents respectively, when MnCo2O4 nanoparticles were chosen as the catalytic surface. This demonstrates that the choice of nanoparticle and solvent (MnCo2O4 nanoparticles and decane) have a great impact on the neutralization of DMMP.
Analytical chemistry
Narges Ajami; Ali Ehsani; Ferydon Babaei; Ashraf Heidaripour
Volume 3, Issue 2, pp. 72-147, Serial No. 7 , April 2015, , Pages 72-77
Abstract
Optical modeling was applied for obtaining absorbance spectra and band gap values for different morphology of ZnO semiconductor. In optical modeling, the relative permittivity scalars of zinc oxide coral like nanorods were calculated using the Bruggeman homogenization formalism. ZnO nano rods (ZONRs) ...
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Optical modeling was applied for obtaining absorbance spectra and band gap values for different morphology of ZnO semiconductor. In optical modeling, the relative permittivity scalars of zinc oxide coral like nanorods were calculated using the Bruggeman homogenization formalism. ZnO nano rods (ZONRs) as a nucleus layer were fabricated on the Indium Tin Oxide (ITO) by chronoamperometry (CA) in aqueous solution containing different concentration of zinc nitrate. Reduction of nitrate anion is a good resource for hydroxyl ion that with zinc anion results ZnO. The orientation and morphology of both the nucleus layer and successive coral like ZONRs were analyzed using X-ray diffraction (XRD).
Analytical chemistry
Ghasem Karim-Nezhad; Ali Pashazadeh
Volume 3, Issue 2, pp. 72-147, Serial No. 7 , April 2015, , Pages 86-95
Abstract
In this research, we reported a novel modified carbon ceramic electrode (CCE) using Ni/Al Layered double hydroxide as modifier was fabricated by sol-gel technique. The Ni/Al Layered double hydroxide modified sol gel derived carbon ceramic (Ni/Al LDH-SGD-CC) electrode was used for electrocatalytic oxidation ...
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In this research, we reported a novel modified carbon ceramic electrode (CCE) using Ni/Al Layered double hydroxide as modifier was fabricated by sol-gel technique. The Ni/Al Layered double hydroxide modified sol gel derived carbon ceramic (Ni/Al LDH-SGD-CC) electrode was used for electrocatalytic oxidation of acetaldehyde. The oxidation of acetaldehyde happens at the potential where Ni (III) species are generated. The modified electrode exhibited remarkable electrocatalytic activity for the oxidation of acetaldehyde under alkaline conditions, indicating that the anodic oxidation of acetaldehyde could be catalyzed at Ni/Al LDH-SGD-CC electrode. This proves that the Ni/Al LDH bears the main role in electro-catalytic oxidation of acetaldehyde. Finally, by using the cyclic voltammetry, chronoamperometric and tafel plots method, the catalytic rate constant, charge-transfer coefficient, the number of electrons involved in the rate-determining step (nα) and exchange current density for chemical reaction of acetaldehyde was estimated as 0.356 × 104 cm3 mol-1 s-1, 0.51, 1 and 2.76×10-8 Acm-2 respectively.
Analytical chemistry
Masoumeh Taei; Foroozan Hasanpour; Marjan Shavakhi
Volume 3, Issue 1, pp. 1-71, Serial No.6 , January 2015, , Pages 16-25
Abstract
A carbon-paste electrode (CPE) chemically modified with the N-4,4'-azodianiline(ferrocenyl Schiff base) complex and multi wall carbon nanotubes (ADAFCNTE) was used as a highly sensitive electrochemical sensor for determination of trace amounts of atenolol. The oxidation peak potentials in cyclic voltammogram ...
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A carbon-paste electrode (CPE) chemically modified with the N-4,4'-azodianiline(ferrocenyl Schiff base) complex and multi wall carbon nanotubes (ADAFCNTE) was used as a highly sensitive electrochemical sensor for determination of trace amounts of atenolol. The oxidation peak potentials in cyclic voltammogram of ADAFCNTE occurred around 550 mV vs Ag/AgCl (at pH 6.0) while this peak potential at the carbon paste electrode appeared around 800 mV at the same scan rate of 10 mV s−1. The kinetic parameters such as electron transfer coefficient, α, and rate constant for chemical reaction between atenolol and redox sites in modified electrode were 0.41 and 2.8×102 cm3 mol-1 s-1, respectively. The catalytic peak current was linearly dependent on atenolol concentration in the range of 0.1-57.0 µmol L-1 with a detection limit of 0.08 µmol L-1. Finally, the sensor was examined as a selective, simple and precise new electrochemical sensor for the determination of atenolol in urine samples, with satisfactory results.
Analytical chemistry
Mohamad Mohsen Momeni; Mohadesah Hakimiyan; Ali Kazempoor; Mahboubeh Mirhosseini; Zohre Nazari; Seyed Mostafa Mirhoseini; Hadi Kargar
Volume 3, Issue 1, pp. 1-71, Serial No.6 , January 2015, , Pages 41-47
Abstract
Cupper Oxide structures with a variety of novel morphologies are synthesized using cupper foil as substrate via a solution route. The structure, morphology and phase of the as-synthesized nanostructures are analyzed by various techniques. SEM images show gradual development of hierarchical structures ...
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Cupper Oxide structures with a variety of novel morphologies are synthesized using cupper foil as substrate via a solution route. The structure, morphology and phase of the as-synthesized nanostructures are analyzed by various techniques. SEM images show gradual development of hierarchical structures of copper oxide with different morphology. In order to study the effect of reaction time and temperature on the morphology of the CuO samples, experiments carried out at temperatures 0 °C and 25 °C for 10 min up to 12h. Results showed that the prepared samples exhibited some novel morphology such as nanorods, nanosheets, microflowers, Cubic shaped structures and Tulip flower-shaped structures.
Analytical chemistry
Fatemeh Sabermahani; Nosrat Madadi Mahani
Volume 3, Issue 1, pp. 1-71, Serial No.6 , January 2015, , Pages 48-56
Abstract
In this work, a new extractant was prepared by immobilizing ligand 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, (5-Br-PADAP), on the activated carbon and applied to extraction of Pb(II) prior to determination by flame atomic absorption spectrometry. It was confirmed by FT- IR analysis. The metal ion ...
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In this work, a new extractant was prepared by immobilizing ligand 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, (5-Br-PADAP), on the activated carbon and applied to extraction of Pb(II) prior to determination by flame atomic absorption spectrometry. It was confirmed by FT- IR analysis. The metal ion was retained on the 0.05 g of the sorbent in the pH range 6-8, and then eluted with 5 mL of 0.5 mol L-1 nitric acid. Seven replicate determinations of a 1.0 µg mL-1 of lead solution in the final solution gave relative standard deviation of 3.3%. The maximum equilibrium capacity of the new sorbent from Langmuir model was 18.2 mg g-1. The linearity was maintained in the concentration range of 0.1-10.0 ng mL-1 for the concentrated solution. The limit of detection based on three times the standard deviation of the blank ( 3σbl/m), was found to be 0.83 ng mL-1 in original solution. Common coexisting ions did not interfere with the separation and determination of lead. The prepared sorbent was applied to the preconcentration of Pb(II) in water and soil samples with satisfactory results.
Organic chemistry
Mehdi Nabati; Mehrdad Mahkam; Hassan Heidari
Volume 2, Issue 4, pp. 236-325, Serial No. 5 , October 2014, , Pages 236-243
Abstract
Turmeric (Curcuma longa L.) is extensively used as a spice, food preservative and colouring material. It has been used in traditional medicine for various diseases. Curcumin, the main yellow bioactive component of turmeric has been shown to have a wide spectrum of biological actions. Heretofore, it has ...
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Turmeric (Curcuma longa L.) is extensively used as a spice, food preservative and colouring material. It has been used in traditional medicine for various diseases. Curcumin, the main yellow bioactive component of turmeric has been shown to have a wide spectrum of biological actions. Heretofore, it has been reported that natural colored extracts isolated from turmeric rhizomes with many methods such as maceration, digestion, microwave and infusion. In this paper, it was tried to isolate and characterize curcumin from the curcumin rhizomes marketed in Maragheh city of Iran by soxhlet extraction technique in methanol solvent. The advantage of this technique is the isolation of large amounts of curcumin (208 mg from 25 g turmeric rhizomes powder) with smaller quantity of methanol.
Analytical chemistry
Burla Sunitha Seshamamba; Peruri Veera Satyanarayana; Chandra Sekharan
Volume 2, Issue 4, pp. 236-325, Serial No. 5 , October 2014, , Pages 255-268
Abstract
Two simple visible spectrophotometric methods are developed and validated for the quantification of modafinil using 1,2-naphthoquinone-4-sulphonic acid (NQS method) and 2,4-dinitrophenol (DNP method) as analytical reagents. The NQS method involves the reaction of modafinil with 1,2-naphthoquinone-4-sulphonate ...
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Two simple visible spectrophotometric methods are developed and validated for the quantification of modafinil using 1,2-naphthoquinone-4-sulphonic acid (NQS method) and 2,4-dinitrophenol (DNP method) as analytical reagents. The NQS method involves the reaction of modafinil with 1,2-naphthoquinone-4-sulphonate in alkaline medium at room conditions to form a yellow colored product exhibiting maximum absorption at 430 nm. DNP method is based on the proton transfer from 2,4-dinitrophenol to modafinil at room conditions and then we have the formation of yellow colored ion-pair complex exhibiting maximum absorption at 475 nm. Different variables affecting the reaction were studied and optimized. Under the optimized experimental conditions, Beer's law is obeyed in the concentration ranges of 10-100 and 8-60 μg/mL with the detection of limit values of 0.486 and 0.258 μg/mL for NQS method and DNP method, respectively The molar absorptivity and Sandell's sensitivity for both of the methods are reported. The methods were validated in terms of accuracy, precision and robustness. The results were satisfactory. The proposed methods were effectively applied to the analysis of the modafinil in their tablet formulations. The recoveries were 99.92% and 99.96% with RSD and 0.863% and 0.722% for NQS and DNS methods, respectively. The assay was not interfered by common excipients.
Analytical chemistry
Hadi Noorizadeh; Sharmin Esmaeilpoor; Zohreh Moghadam; Shahnaz Nosratolahy
Volume 2, Issue 4, pp. 236-325, Serial No. 5 , October 2014, , Pages 283-299
Abstract
The veterinary drugs residues are also important pollutants found in milk, since veterinary drugs are commonly used in cattle management. Considering the role of milk in human nutrition and its wide consumption throughout the world, it is very important to ensure the milk quality. A quantitative structure–retention ...
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The veterinary drugs residues are also important pollutants found in milk, since veterinary drugs are commonly used in cattle management. Considering the role of milk in human nutrition and its wide consumption throughout the world, it is very important to ensure the milk quality. A quantitative structure–retention relationship (QSRR) was developed using the partial least square (PLS), Kernel PLS (KPLS) and Levenberg-Marquardt artificial neural network (L-M ANN) approach for chemometrics study. Genetic algorithm was employed as a factor selection procedure for PLS and KPLS modeling methods. By comparing the results, GA-KPLS descriptors are selected for L-M ANN. Finally a model with a low prediction error and a good correlation coefficient was obtained by L-M ANN. This is the first research on the QSRR of veterinary drugs using the chemometrics models.
Analytical chemistry
Behnam Hafezi
Volume 2, Issue 3, pp. 162-231, Serial No. 4 , July 2014, , Pages 222-231
Abstract
In this work, a tracer study on pore initiation in anodic alumina in oxalic acid was performed. Effects of some experimental parameters such as applied electrical potential, electrolyte composition and heat pretreatment were evaluated. Electrochemical and morphological experiments were performed using ...
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In this work, a tracer study on pore initiation in anodic alumina in oxalic acid was performed. Effects of some experimental parameters such as applied electrical potential, electrolyte composition and heat pretreatment were evaluated. Electrochemical and morphological experiments were performed using potentiostatic anodizing and scanning electron microscopy (SEM) techniques, respectively. Effect of electrolyte composition on current density was discussed. In various electrical potentials, electrolyte composition had different effects on current density. Addition of sulfuric acid into oxalic acid increased porosity. Also, distribution of pore size and pore diameter were influenced by presence of sulfuric acid. Effect of electrolyte composition on the morphology of aluminum surface layer was depended on to the electric potential. Current density and porosity of aluminum surface layer was decreased by heat pretreatment.
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