The electrochemical behavior of vitamin C（ascorbic acid or AA） is investigated on the surface of a carbon-paste electrode modified with TiO2 nanoparticles and 2,2＇-（1,2 butanediylbis（nitriloethylidyne））-bis-hyd...The electrochemical behavior of vitamin C（ascorbic acid or AA） is investigated on the surface of a carbon-paste electrode modified with TiO2 nanoparticles and 2,2＇-（1,2 butanediylbis（nitriloethylidyne））-bis-hydroquinone（BBNBH）.The prepared modified electrode showed an efficient catalytic role in the electrochemical oxidation of AA,leading to remarkable decrease in oxidation overpotential and enhancement of the kinetics of the electrode reaction.This modified electrode exhibits well-separated oxidation peaks for AA and uric acid（UA）.The modified electrode is successfully applied for the accurate determination of AA in pharmaceutical preparations.展开更多
A magnetic bar carbon paste electrode （MBCPE） modified with Fe3O4 magnetic nanoparticles （Fe3O4NPs） and 2‐（3,4‐dihydroxyphenyl） benzothiazole （DPB） for the electrochemical determina‐tion of hydrazine was de...A magnetic bar carbon paste electrode （MBCPE） modified with Fe3O4 magnetic nanoparticles （Fe3O4NPs） and 2‐（3,4‐dihydroxyphenyl） benzothiazole （DPB） for the electrochemical determina‐tion of hydrazine was developed. The DPB was firstly self‐assembled on the Fe3O4NPs, and the re‐sulting Fe3O4NPs/DPB composite was then absorbed on the designed MBCPE. The MBCPE was used to attract the magnetic nanoparticles to the electrode surface. Owing to its high conductivity and large effective surface area, the novel electrode had a very large current response for the electrocat‐alytic oxidation of hydrazine. The modified electrode was characterized by voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy, infrared spectroscopy, and UV‐visible spectroscopy. Voltammetric methods were used to study the electrochemical behaviour of hydrazine on MBCPE/Fe3O4NPs/DPB in phosphate buffer solution （pH = 7.0）. The MBCPE/Fe3O4NPs/DPB, acting as an electrochemical sensor, exhibited very high electrocatalytic activity for the oxidation of hydrazine. The presence of DPB was found to reduce the oxidation potential of hydrazine and increase the catalytic current. The dependence of the electrocatalytic current on the hydrazine concentration exhibited two linear ranges, 0.1–0.4 μmol/L and 0.7–12.0 μmol/L, with a detection limit of 18.0 nmol/L. Additionally, the simultaneous determination of hydrazine and phe‐nol was investigated using the MBCPE/Fe3O4NPs/DPB electrode. Voltammetric experiments showed a linear range of 100–470 μmol/L and a detection limit of 24.3 μmol/L for phenol, and the proposed electrode was applied to the determination of hydrazine and phenol in water samples.展开更多
Electrochemical investigation of catechol using square wave voltammetry with anthraquinone modified carbon paste electrode was found to be very sensitive. Compared with the unmodified carbon paste electrode, the anthr...Electrochemical investigation of catechol using square wave voltammetry with anthraquinone modified carbon paste electrode was found to be very sensitive. Compared with the unmodified carbon paste electrode, the anthraquinone modified electrode remarkably increases the peak currents of catechol, and greatly lowers the peak potential separation. Two varieties of tea, namely green, and black variety: Wush Wush tea, from Ethiopia, known by its brand name were investigated. Responses for the extracts using ethanol: water (1:4) % v/v showed green tea to be superior in catechol content. Optimization of different variables such as pH of working solution, modifier composition and square wave parameters such as frequency, amplitude and step potential were made to improve the method efficiency during the experiment. The reproducibility for the nine repeated analysis of 80 μmol·L-1 of catechol gave a relative standard deviation of 3.65% and linear calibration plots were obtained in the range 6 to 80 μmol·L-1 with (R = 0.998) and the detection limit with (S/N = 3) was as low as 2.155 x 10-7 mol·L-1.展开更多
A new ascorbic acid sensor constituted of carbon paste and Fe(Ⅲ)Y zeolite was studied.The characters of the sensor such as linear range. potential window、apparen Michaelis constant、response time、stability and accu...A new ascorbic acid sensor constituted of carbon paste and Fe(Ⅲ)Y zeolite was studied.The characters of the sensor such as linear range. potential window、apparen Michaelis constant、response time、stability and accuracy wee investigated. The experimental results indicate that the analytical performance of the sensor is satisfactory.展开更多
The new ferrous-selective modified carbon paste electrodes (I and II) based on 5,5’-(propane-1,3-diylbis(sulfanediyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode I, A-ionophore) and 5,5’-(butane-1,4-diyl-bis(s...The new ferrous-selective modified carbon paste electrodes (I and II) based on 5,5’-(propane-1,3-diylbis(sulfanediyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode I, A-ionophore) and 5,5’-(butane-1,4-diyl-bis(sulfane- diyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode II, B-ionophore) as ionophores are described. These electrodes exhibit Nernstian slopes of 30.2 ± 0.5 and 29.1 ± 0.5 mV·decade-1, linear range of 1.0 × 10-7 - 1.0 × 10-2 mol·L-1 Fe(II) ion and detection limit of 1.0 × 10-7 mol·L-1 Fe(II) ion for electrode (I) and electrode (II), respectively. Both electrodes (I and II) have a fast response time of about 15 sand can be used for at least 3 months. The two electrodes revealed a good selectivity for Fe(II) over a wide variety of other metal ions and could be used in the pH range of 1.8 - 3.0 without any divergence in potential. The proposed sensors were successfully applied for the determination of Fe(II) ion in different real samples.展开更多
A kind of inorganic-organic hybrid semiconductor composite nanoparticles： Dawson-type phosphomolybdate- doped polypyrrole （P2Mo18-PPy） was designed and prepared using microemulsion oxidation-polymerization at room ...A kind of inorganic-organic hybrid semiconductor composite nanoparticles： Dawson-type phosphomolybdate- doped polypyrrole （P2Mo18-PPy） was designed and prepared using microemulsion oxidation-polymerization at room temperature and characterized by TEM and IR. The P2Mo18-PPy was used as a bulk-modifier to fabricate a chemically modified carbon paste electrode（CPE） by direct mixing, which represents the example of polyoxometalates（ POMs）- doped semiconductor polymer nanoparticles modified electrode. Both the advantage of POMs-doped polymer and the surface-renewal property of the CPE were fully utilized. The electrochemical behavior of the P2Mo18-PPY bulk-modified CPE（P2Mo18-PPy-CPE） was investigated with cyclic voltammetry. Three couples of reversible redox peaks were observed in the range from ＋ 800 to 0 mV, which corresponded to the reduction and oxidation through two-, four- and six-electron processes, respectively. The P2 Mo18-PPY-CPE showed a high electrocatalytic activity for the reduction of nitrite, which expanded the application of POMs-doped semiconductor polymer nanoparticles.展开更多
In this research, copper oxide nanoparticles modified carbon paste electrode was developed for the voltammetric determination of lidocaine. The square wave voltammogram of lidocaine solution showed a well-defined peak...In this research, copper oxide nanoparticles modified carbon paste electrode was developed for the voltammetric determination of lidocaine. The square wave voltammogram of lidocaine solution showed a well-defined peak between ＋0.5 and ＋1.5 V. Instrumental and chemical parameters influencing voltammetric response were optimized by both one at a time and Box–Behnken model of response surface methodology. The results revealed that there was no significant difference between two methods of optimization. The linear range was 1–2500 μmol L^-1（Ip= 0.11 C（LH）＋ 17.38, R^2= 0.999）. The LOD and LOQ based on three and ten times of the signal to noise（S/N） were 0.39 and 1.3 μmol L^-1（n = 10）,respectively. The precision of the method was assessed for 10 replicate square wave voltammetry（SWV）determinations each of 0.05, 0.5 and 1 μmol L^-1 of lidocaine showing relative standard deviations 4.1%,3.7% and 2.1%, respectively. The reliability of the proposed method was established by application of the method for the determination of lidocaine in two pharmaceutical preparations, namely injection and gel.展开更多
A carbon paste modified sensor based on a novel composite of zinc oxide nanoparticles deposited on reduced graphene oxide(ZnO-rGrO) and Prussian blue(PB) was drop-cast(ZnO-rGrO-PB/MCPE) for the sensitive estimation of...A carbon paste modified sensor based on a novel composite of zinc oxide nanoparticles deposited on reduced graphene oxide(ZnO-rGrO) and Prussian blue(PB) was drop-cast(ZnO-rGrO-PB/MCPE) for the sensitive estimation of Rutin(Rtn) at pH 7.0.The high surface area of ZnO-rGrO and electrocatalytic property of PB promotes the oxidation of Rtn. Field emission scanning electron microscope(FE-SEM) and energy-dispersive X-ray spectroscopy(EDX) techniques were employed to confirm the deposition of ZnO-rGrO and PB on carbon paste electrode(CPE). The ability of ZnO-rGrO-PB/MCPE in charge transfer at the interface was investigated using electrochemical impedance spectroscopy(EIS). The heterogeneous rate constant(ks) and the charge transfer coefficient(α) have been calculated as 6.08 s^(-1) and 0.74 respectively. This sensor showed a wide linear response for Rtn from 7.0×10^(-8)to 7.0×10^(-6) M and 7.0×10^(-6) to 1.0×10^(-4) M with a limit of detection(2.05±0.04)×10^(-8) M(S/N=3). The application of ZnO-rGrO-PB/MCPE was found in the analysis of Rtn in fruit juice samples using standard addition method. This sensor showed good reproducibility, stability, selectivity and sensitivity.展开更多
A kind of inorganic organic hybrid 18 molybdodiphosphate nanoparticles ([(C 4H 9) 4N] 6P 2Mo 18 O 62 ·4H 2O) was firstly used as a bulk modifier to fabricate a three dimensional chemically modi...A kind of inorganic organic hybrid 18 molybdodiphosphate nanoparticles ([(C 4H 9) 4N] 6P 2Mo 18 O 62 ·4H 2O) was firstly used as a bulk modifier to fabricate a three dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square wave voltammetry. The hybrid 18 molybdodiphosphate nanoparticles bulk modified CPE (MNP CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP CPE over the traditional polyoxometalates modified electrodes are their excellent reproducibility of surface renewal and high stability owing to the insolubility of the hybrid 18 molybdodiphosphate nanoparticles.展开更多
The homogeneous electrocatalytic oxidation of hydrazine（HZ） has been studied by indigocarmine（IND） as a mediator at the surface of TiO_2 nanoparticles modified carbon paste electrode（TNMCPE）.Cyclic voltammetry w...The homogeneous electrocatalytic oxidation of hydrazine（HZ） has been studied by indigocarmine（IND） as a mediator at the surface of TiO_2 nanoparticles modified carbon paste electrode（TNMCPE）.Cyclic voltammetry was used to study the electrochemical behavior of IND at different scan rates.The voltammetric response of the modified electrode was linear against the concentration of HZ in the ranges of 3.0×l0^（-8）-7.0×10~6 mol/L with differential pulse voltammetry method.The detection limit（3σ） was determined as 27.3 nmol/L.To evaluate the applicability of the proposed method to real samples,the modified CPE was applied to the determination of HZ in water samples.展开更多
文摘The electrochemical behavior of vitamin C（ascorbic acid or AA） is investigated on the surface of a carbon-paste electrode modified with TiO2 nanoparticles and 2,2＇-（1,2 butanediylbis（nitriloethylidyne））-bis-hydroquinone（BBNBH）.The prepared modified electrode showed an efficient catalytic role in the electrochemical oxidation of AA,leading to remarkable decrease in oxidation overpotential and enhancement of the kinetics of the electrode reaction.This modified electrode exhibits well-separated oxidation peaks for AA and uric acid（UA）.The modified electrode is successfully applied for the accurate determination of AA in pharmaceutical preparations.
文摘A magnetic bar carbon paste electrode （MBCPE） modified with Fe3O4 magnetic nanoparticles （Fe3O4NPs） and 2‐（3,4‐dihydroxyphenyl） benzothiazole （DPB） for the electrochemical determina‐tion of hydrazine was developed. The DPB was firstly self‐assembled on the Fe3O4NPs, and the re‐sulting Fe3O4NPs/DPB composite was then absorbed on the designed MBCPE. The MBCPE was used to attract the magnetic nanoparticles to the electrode surface. Owing to its high conductivity and large effective surface area, the novel electrode had a very large current response for the electrocat‐alytic oxidation of hydrazine. The modified electrode was characterized by voltammetry, scanning electron microscopy, electrochemical impedance spectroscopy, infrared spectroscopy, and UV‐visible spectroscopy. Voltammetric methods were used to study the electrochemical behaviour of hydrazine on MBCPE/Fe3O4NPs/DPB in phosphate buffer solution （pH = 7.0）. The MBCPE/Fe3O4NPs/DPB, acting as an electrochemical sensor, exhibited very high electrocatalytic activity for the oxidation of hydrazine. The presence of DPB was found to reduce the oxidation potential of hydrazine and increase the catalytic current. The dependence of the electrocatalytic current on the hydrazine concentration exhibited two linear ranges, 0.1–0.4 μmol/L and 0.7–12.0 μmol/L, with a detection limit of 18.0 nmol/L. Additionally, the simultaneous determination of hydrazine and phe‐nol was investigated using the MBCPE/Fe3O4NPs/DPB electrode. Voltammetric experiments showed a linear range of 100–470 μmol/L and a detection limit of 24.3 μmol/L for phenol, and the proposed electrode was applied to the determination of hydrazine and phenol in water samples.
文摘Electrochemical investigation of catechol using square wave voltammetry with anthraquinone modified carbon paste electrode was found to be very sensitive. Compared with the unmodified carbon paste electrode, the anthraquinone modified electrode remarkably increases the peak currents of catechol, and greatly lowers the peak potential separation. Two varieties of tea, namely green, and black variety: Wush Wush tea, from Ethiopia, known by its brand name were investigated. Responses for the extracts using ethanol: water (1:4) % v/v showed green tea to be superior in catechol content. Optimization of different variables such as pH of working solution, modifier composition and square wave parameters such as frequency, amplitude and step potential were made to improve the method efficiency during the experiment. The reproducibility for the nine repeated analysis of 80 μmol·L-1 of catechol gave a relative standard deviation of 3.65% and linear calibration plots were obtained in the range 6 to 80 μmol·L-1 with (R = 0.998) and the detection limit with (S/N = 3) was as low as 2.155 x 10-7 mol·L-1.
文摘A new ascorbic acid sensor constituted of carbon paste and Fe(Ⅲ)Y zeolite was studied.The characters of the sensor such as linear range. potential window、apparen Michaelis constant、response time、stability and accuracy wee investigated. The experimental results indicate that the analytical performance of the sensor is satisfactory.
文摘The new ferrous-selective modified carbon paste electrodes (I and II) based on 5,5’-(propane-1,3-diylbis(sulfanediyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode I, A-ionophore) and 5,5’-(butane-1,4-diyl-bis(sulfane- diyl))bis(3-benzyl-4H-1,2,4-triazol-4-amine) (electrode II, B-ionophore) as ionophores are described. These electrodes exhibit Nernstian slopes of 30.2 ± 0.5 and 29.1 ± 0.5 mV·decade-1, linear range of 1.0 × 10-7 - 1.0 × 10-2 mol·L-1 Fe(II) ion and detection limit of 1.0 × 10-7 mol·L-1 Fe(II) ion for electrode (I) and electrode (II), respectively. Both electrodes (I and II) have a fast response time of about 15 sand can be used for at least 3 months. The two electrodes revealed a good selectivity for Fe(II) over a wide variety of other metal ions and could be used in the pH range of 1.8 - 3.0 without any divergence in potential. The proposed sensors were successfully applied for the determination of Fe(II) ion in different real samples.
基金Supported by Natural Science Foundation of Liaoning Province(No. 20032138) and Education Committee Foundation of Liaon-ing Province(No. 2004F023).
文摘A kind of inorganic-organic hybrid semiconductor composite nanoparticles： Dawson-type phosphomolybdate- doped polypyrrole （P2Mo18-PPy） was designed and prepared using microemulsion oxidation-polymerization at room temperature and characterized by TEM and IR. The P2Mo18-PPy was used as a bulk-modifier to fabricate a chemically modified carbon paste electrode（CPE） by direct mixing, which represents the example of polyoxometalates（ POMs）- doped semiconductor polymer nanoparticles modified electrode. Both the advantage of POMs-doped polymer and the surface-renewal property of the CPE were fully utilized. The electrochemical behavior of the P2Mo18-PPY bulk-modified CPE（P2Mo18-PPy-CPE） was investigated with cyclic voltammetry. Three couples of reversible redox peaks were observed in the range from ＋ 800 to 0 mV, which corresponded to the reduction and oxidation through two-, four- and six-electron processes, respectively. The P2 Mo18-PPY-CPE showed a high electrocatalytic activity for the reduction of nitrite, which expanded the application of POMs-doped semiconductor polymer nanoparticles.
基金funding provided by Jundishapur University of Medical Sciences–Nanotechnology Research Center under grant No.N-11
文摘In this research, copper oxide nanoparticles modified carbon paste electrode was developed for the voltammetric determination of lidocaine. The square wave voltammogram of lidocaine solution showed a well-defined peak between ＋0.5 and ＋1.5 V. Instrumental and chemical parameters influencing voltammetric response were optimized by both one at a time and Box–Behnken model of response surface methodology. The results revealed that there was no significant difference between two methods of optimization. The linear range was 1–2500 μmol L^-1（Ip= 0.11 C（LH）＋ 17.38, R^2= 0.999）. The LOD and LOQ based on three and ten times of the signal to noise（S/N） were 0.39 and 1.3 μmol L^-1（n = 10）,respectively. The precision of the method was assessed for 10 replicate square wave voltammetry（SWV）determinations each of 0.05, 0.5 and 1 μmol L^-1 of lidocaine showing relative standard deviations 4.1%,3.7% and 2.1%, respectively. The reliability of the proposed method was established by application of the method for the determination of lidocaine in two pharmaceutical preparations, namely injection and gel.
基金supported by Board of Research in Nuclear Sciences (BRNS, BARC, Mumbai)Department of Atomic Energy, Government of India (37(2)/14/10/2014-brns)
文摘A carbon paste modified sensor based on a novel composite of zinc oxide nanoparticles deposited on reduced graphene oxide(ZnO-rGrO) and Prussian blue(PB) was drop-cast(ZnO-rGrO-PB/MCPE) for the sensitive estimation of Rutin(Rtn) at pH 7.0.The high surface area of ZnO-rGrO and electrocatalytic property of PB promotes the oxidation of Rtn. Field emission scanning electron microscope(FE-SEM) and energy-dispersive X-ray spectroscopy(EDX) techniques were employed to confirm the deposition of ZnO-rGrO and PB on carbon paste electrode(CPE). The ability of ZnO-rGrO-PB/MCPE in charge transfer at the interface was investigated using electrochemical impedance spectroscopy(EIS). The heterogeneous rate constant(ks) and the charge transfer coefficient(α) have been calculated as 6.08 s^(-1) and 0.74 respectively. This sensor showed a wide linear response for Rtn from 7.0×10^(-8)to 7.0×10^(-6) M and 7.0×10^(-6) to 1.0×10^(-4) M with a limit of detection(2.05±0.04)×10^(-8) M(S/N=3). The application of ZnO-rGrO-PB/MCPE was found in the analysis of Rtn in fruit juice samples using standard addition method. This sensor showed good reproducibility, stability, selectivity and sensitivity.
文摘A kind of inorganic organic hybrid 18 molybdodiphosphate nanoparticles ([(C 4H 9) 4N] 6P 2Mo 18 O 62 ·4H 2O) was firstly used as a bulk modifier to fabricate a three dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square wave voltammetry. The hybrid 18 molybdodiphosphate nanoparticles bulk modified CPE (MNP CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP CPE over the traditional polyoxometalates modified electrodes are their excellent reproducibility of surface renewal and high stability owing to the insolubility of the hybrid 18 molybdodiphosphate nanoparticles.
文摘The homogeneous electrocatalytic oxidation of hydrazine（HZ） has been studied by indigocarmine（IND） as a mediator at the surface of TiO_2 nanoparticles modified carbon paste electrode（TNMCPE）.Cyclic voltammetry was used to study the electrochemical behavior of IND at different scan rates.The voltammetric response of the modified electrode was linear against the concentration of HZ in the ranges of 3.0×l0^（-8）-7.0×10~6 mol/L with differential pulse voltammetry method.The detection limit（3σ） was determined as 27.3 nmol/L.To evaluate the applicability of the proposed method to real samples,the modified CPE was applied to the determination of HZ in water samples.
