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New polypyrrole–carbon nanotubes–silicon dioxide solid‐phase microextraction fiber for the preconcentration and determination of benzene,toluene, ethylbenzene,and o‐xylene using gas liquid chromatography
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Ali Sarafraz‐Yazdi Gholamhossein Rounaghi Iman Razavipanah Hossein Vatani Amirhassan Amiri 《Journal of separation science》2014,37(18):2605-2612
For the first time, a polypyrrole–carbon nanotubes–silicon dioxide composite film coated on a steel wire was prepared by an electrochemical method. Scanning electron microscopy images showed that this composite film was even and porous. The prepared fiber was used as an absorbent for the headspace solid‐phase microextraction of benzene, toluene, ethylbenzene, and o‐xylene, followed by gas chromatographic analysis. This method presented an excellent performance, which was much better than that of a polypyrrole–carbon nanotube fiber. It was found that under the optimized conditions, the linear ranges were 0.01–200 ng/mL with correlation coefficients >0.9953, the detection limits were 0.005–0.020 ng/mL, the relative standard deviations were 3.9–6.4% for five successive measurements with a single fiber, and the reproducibility was 5.5–8.5% (n = 3). Finally, the developed method was successfully applied to real water samples, and the relative recoveries obtained for the spiked water samples were from 91.0 to 106.7%. 相似文献
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G. H. Rounaghi E. Razavipanah F. Kaveh 《Journal of inclusion phenomena and macrocyclic chemistry》2010,68(3-4):245-252
The stability constants of 1:1 (M:L) complexes of benzo-15-crown-5 (B15C5) with Li+, Na+, K+ and NH4 + cations, the Gibbs standard free energies ( $ \Updelta {\text{G}}_{\text{c}}^{ \circ } $ ), the standard enthalpy changes ( $ \Updelta {\text{H}}_{\text{c}}^{ \circ } $ ) and standard entropy changes ( $ \Updelta {\text{S}}_{\text{c}}^{ \circ } $ ) for formation of these complexes in acetonitrile–methanol (AN–MeOH) binary mixtures have been determined conductometrically. The conductance data show that the stoichiometry of the complexes formed between the macrocyclic ligand and the studied cations is 1:1 (M:L). In most cases, addition of B15C5 to solutions of these cations, causes a continuous increase in the molar conductivities which indicates that the mobility of complexed cations is more than the uncomplexed ones. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program, GENPLOT. The results show that the selectivity order of B15C5 for the metal cations changes with the nature and composition of the binary mixed solvent. The values of standard enthalpy changes ( $ \Updelta {\text{H}}_{\text{c}}^{ \circ } $ ) for complexation reactions were obtained from the slope of the van’t Hoff plots and the changes in standard entropy ( $ \Updelta {\text{S}}_{\text{c}}^{ \circ } $ ) were calculated from the relationship $ \Updelta {\text{G}}_{{{\text{c}},298.15}}^{ \circ } = \Updelta {\text{H}}_{\text{c}}^{ \circ } - 298.15\Updelta {\text{S}}_{\text{c}}^{ \circ } $ . A non-linear behavior was observed between the stability constants (log Kf) of the complexes and the composition of the acetonitrile–methanol (AN–MeOH) binary solution. The results obtained in this study, show that in most cases, the complexes formed between B15C5 and Li+, Na+, K+ and NH4 + cations are both enthalpy and entropy stabilized and the values of these thermodynamic quantities change with the composition of the binary solution. 相似文献
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Sarafraz-Yazdi Ali Rounaghi Gholamhossein Vatani Hossein Razavipanah Iman Amiri Amirhassan 《Mikrochimica acta》2015,182(1-2):217-225
Microchimica Acta - We have prepared a new material for solid-phase microextraction (SPME) of volatile aromatic hydrocarbons by electropolymerization of pyrrole, carbon nanotubes, and titanium... 相似文献
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Mostafa Gholizadeh Gholam Hossien Rounaghi Iman Razavipanah Mohammad Reza Salavati 《Journal of the Iranian Chemical Society》2014,11(4):947-952
To understand the effect of a magnetized solvent upon complexation processes between the metal ions and the ligands, we studied the complexation reaction between Y+3 cation with the kryptofix 22DD, in non-magnetized and magnetized methanol solvents at different temperatures using the conductometric method. Addition of kryptofix 22DD to the cation solution causes a continuous increase in the molar conductivities which indicates that the mobility of the complexed cation is higher than the uncomplexed one in both non-magnetized and magnetized methanol solvents. The conductance data show that the stoichiometry of the complex formed between the ligand and Y3+ cation is 1:1(M:L). The value of stability constant of (kryptofix 22DD.Y)3+ complex was determined from conductometric data using a non-linear least-square program (GENPLOT). The results obtained in this investigation, show that the stability constant of the complex decreases when we use magnetized methanol solvent. 相似文献
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G. H. Rounaghi E. Razavipanah 《Journal of inclusion phenomena and macrocyclic chemistry》2008,61(3-4):313-318
The complexation processes between Li+, Na+, K+ and NH 4 + cations with macrocyclic ligand, 4′-nitrobenzo-15C5, were studied in acetonitrile–methanol (AN–MeOH) binary mixtures at different temperatures using conductometric method. The conductance data show that the stoichiometry of the complexes formed between the ligand and Li+, Na+, K+ and NH 4 + cations is 1:1(M:L). Addition of 4′-nitrobenzo-15C5 to these cations solution, causes a continuous increase in the molar conductivities which indicates that the mobility of the complexed cations is more than the uncomplexed ones. The values of stability constants of the complexes were determined from conductometric data using GENPLOT computer program. The obtained results show that the selectivity order of the ligand for Li+, Na+, K+ and NH 4 + cations changes with the nature and composition of the binary mixed solvent. The values of thermodynamic parameters (ΔH°c, ΔS°c) for formation of the complexes were obtained from temperature dependence of the stability constants using the van’t Hoff plot. The results show that the complexes are both enthalpy and entropy stabilized. A non-linear behavior was observed between the stability constants (log K f ) of the complexes and the composition of the AN–MeOH binary solution. 相似文献
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Structural Chemistry - The detection methods used to analyze abused drugs should be sensitive sufficiently. Here in, we propose carbon nanotube (CNT) functionalized with COOH and CONHCH3 groups as... 相似文献
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Iman Razavipanah Gholam Hossein Rounaghi Mohammad Hossien Arbab Zavvar 《Journal of the Iranian Chemical Society》2013,10(6):1279-1289
A nanocatalyst coating was prepared at surface of a glassy carbon electrode by electropolymerization of pyrrole by cycling the electrode potential between ?0.8 and 0.8 V (vs. Ag/AgCl). Then, polypyrrole film was potentiostatically coated with platinum nanoparticles at constant potential of ?0.2 V (vs. Ag/AgCl). The resulting electrode was denoted as GCE/PPy/Pt. This modified electrode was characterized by IR, SEM, TEM and EDX. The electrocatalytic oxidation of ethanol at the GCE/PPy/Pt has been investigated using cyclic voltammetric and chronoamperometric methods. The effects of various parameters on electrocatalytic oxidation of the ethanol, such as the thickness of PPy film, the amount of platinum nanoparticles, ethanol concentration, potential scan rate and working potential limit in anodic direction, were investigated. The kinetic of the ethanol oxidation is discussed on the GCE/PPy/Pt. The stability and reproducibility of this modified electrode were also studied. 相似文献
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Construction of an Amperometric Glucose Biosensor by Immobilization of Glucose Oxidase on Nanocomposite at the Surface of FTO Electrode
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Zahra Rezay Marand Nasser Shahtahmassebi Mohammad Reza Housaindokht Golam Hossien Rounaghi Iman Razavipanah 《Electroanalysis》2014,26(4):840-848
Fluorine? tin oxide (FTO) nanostructure was developed on the surface of a glass plate using spray payroliziz method. A new electrochemical biosensor was fabricated based on a layer by layer process. In this process chitosan? Fe3O4 (CH? Fe3O4) nanocomposite film was prepared at the surface of FTO electrode by dip? coating method. In the next step, the glucose oxidase (GOx) was immobilized on the CH? Fe3O4/FTO nanocomposite electrode. The GOx/CH? Fe3O4/FTO bioelectrode has a linear range of 10–270 µM and a detection limit of 5 µM. The highest sensitivity was obtained at 1.2 µA mM?1 cm?2. 相似文献
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Gholam Hossein Rounaghi Iman Razavipanah Behjat Deiminiat Fahimeh Razghandi Esmat Koohsarian Najmeh Abedinzadeh 《Journal of the Iranian Chemical Society》2014,11(3):599-606
The complexation processes among Li+, Na+, K+, and NH4 + cations with the macrocyclic ligand, 15-crown-5 (15C5) have been studied in acetonitrile–methanol binary mixtures at different temperatures using conductometric method. The stability constants of the resulting 1:1 complexes were calculated from the computer fitting of the molar conductance–mole ratio data at various temperatures. The values of thermodynamic parameters ( $ \Updelta H_{\text{c}}^{^\circ } $ and $ \Updelta S_{\text{c}}^{^\circ } $ ) for the formation of the complexes were obtained from temperature dependence of the stability constants of complexes using van’t Hoff plots. In addition, a theoretical study has been carried out using density functional theory to obtain the stability of the complexes and the geometrical structure of the 15C5 and its complexes with Li+, Na+, K+ and NH4 + cations in the gas phase. We compared the experimental data with those obtained by quantum chemistry calculations to investigate the effect of the solvent on complexation process. 相似文献
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