共查询到10条相似文献,搜索用时 125 毫秒
1.
Javad Vahedi Hassan Karimi-Maleh Mehdi Baghayeri Asfaneh L. Sanati Mohammad A. Khalilzadeh Mehrnaz Bahrami 《Ionics》2013,19(12):1907-1914
In this study, we describe an ionic liquid–MgO nanoparticle modified carbon paste electrode (MgO/NPs/IL/CPE) was used as a simple, fast, and sensitive tool for the investigation of the electrochemical oxidation of methyldopa (MDOP) using voltammetric methods. The MgO/NPs was characterized with different methods such as TEM, SEM, and XRD. The oxidation peak potential of the MDOP at a surface of MgO/NPs/IL/CPE appeared at 450 mV that was about 100 mV lower than the oxidation peak potential at the surface of the traditional carbon paste electrode (CPE) under similar conditions. The electro-oxidation of MDOP occurred in a pH-dependent 2e? and 2H+ process, and the electrode reaction followed a diffusion-controlled pathway. Under optimal conditions at pH 7.0, the anodic peak currents increased linearly with the concentration of MDOP in the range of 0.08–380 μmol L?1 with a detection limit of 0.03 μmol L?1 (3σ). The proposed sensor was successfully applied to the determination of MDOP in real samples such as drug and urine. 相似文献
2.
Ionic liquid/multiwall carbon nanotubes paste electrode has been used as a novel sensor for the efficient quantitative determination of methyldopa (MDOP) in pharmaceutical and biological samples by using square wave voltammetry. This new sensor shows a better electrochemical response with lower over-potential and high sensitivity for MDOP compared with unmodified carbon paste electrode in physiological condition. The electro-oxidation of MDOP occurred in a pH-dependent 2e? and 2H+ process, and the electrode reaction followed a diffusion-controlled pathway. Under the optimum conditions, the voltammetric oxidation peak current of MDOP showed two linear dynamic ranges with a detection limit of 0.1 μM for MDOP. The novel sensor has been found selective and successfully implemented for the determination of MDOP in real samples such as tablet and patient urine. 相似文献
3.
The electrooxidation of hydrochlorothiazide (HCT) at the surface of a benzoylferrocene modified multi-walled carbon nanotube paste electrode was studied using electrochemical approaches. Under the optimized conditions (pH 7.0), the square wave voltammetric peak current of HCT increased linearly with HCT concentration in the ranges of 6.0?×?10?7 to 3.0?×?10?4 M. The detection limit was 9.0?×?10?8 M HCT. The diffusion coefficient (D?=?1.75?×?10?5 cm2/s) and electron transfer coefficient (α?=?0.45) for HCT oxidation were also determined. The proposed sensor was successfully applied for the determination of HCT in human urine and tablet samples. 相似文献
4.
Hadi Beitollahi Alireza Mohadesi Saeedeh Khalilizadeh Mahani Hassan Karimi-Maleh Ali Akbari 《Ionics》2012,18(7):703-710
A carbon paste electrode modified with 5-amino-3??,4??-dimethoxy-biphenyl-2-ol and carbon nanotubes was used for the sensitive voltammetric determination of norepinephrine (NE). The electrochemical response characteristics of the modified electrode toward NE, acetaminophen (AC), and folic acid (FA) were investigated by cyclic and square wave voltammetry (SWV). The results show an efficient catalytic activity of the electrode for the electrooxidation of NE, which leads to lowering its overpotential more than 160?mV. The modified electrode exhibits an efficient electron-mediating behavior together with well-separated oxidation peaks for NE, AC, and FA. Under the optimum pH of 7.0 in 0.1?M phosphate buffer solution, the SWV anodic peak current showed a linear relation vs. NE concentration in the range of 15.0 to 1,000.0???M with a detection limit of 8.0???M. 相似文献
5.
Hossein Soltani Hadi Beitollahi Abdol-Hamid Hatefi-Mehrjardi Somayeh Tajik Masoud Torkzadeh Mahani 《Ionics》2014,20(10):1481-1488
A carbon paste electrode modified with benzoylferrocene (BF) and carbon nanotubes (CNTs) have been applied to the electrocatalytic oxidation of homocysteine which reduced the overpotential by about 165 mV with an obvious increase in the current response. The transfer coefficient (α) for the electrocatalytic oxidation of homocysteine and diffusion coefficient of this substance under the experimental conditions were also investigated. In a phosphate buffer solution (PBS) of pH 7.0, the oxidation current increased linearly with two concentration intervals of homocysteine; one is 0.1 to 10.0 μM, and the other is 10.0 to 80.0 μM. The detection limit (3σ) obtained by square wave voltammetry (SWV) was 50.0 nM. The proposed method was successfully applied to the determination of homocysteine in real samples. 相似文献
6.
An ionic liquid-modified carbon nanotubes paste electrode (IL/CNTPE) has been fabricated using hydrophilic ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) as a binder. This electrode showed enhanced electrochemical response and strong analytical activity towards the direct electrochemical oxidation of diclofenac (DCF). The electron transfer coefficient, α, and charge transfer resistance (R ct) of DCF at the modified electrode were calculated. Under optimal conditions at pH 7.0, the anodic peak currents increased linearly with the concentration of DCF in the range of 0.5–300 μmol L?1 with a detection limit of 0.2 μmol L?1 (3σ). The interferences of foreign substances were investigated. Differential pulse voltammetry was used to check the applicability of the proposed sensor to the determination of DCF in real samples with satisfactory results. 相似文献
7.
A novel carbon paste electrode modified with graphene nanosheets and an ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) was fabricated and used for the electrochemical study of mangiferin for the first time. This modified electrode offers a considerable improvement in voltammetric sensitivity toward mangiferin, compared to the bare electrode. Square wave voltammetry (SWV) exhibits a linear dynamic range from 5.0?×?10?8 to 2.0?×?10?4 M and a detection limit of 20.0 nM for mangiferin. Finally, the proposed method was successfully applied to the determination of mangiferin in real samples such as serum and urine. 相似文献
8.
This paper presents a sensitive electrochemical method for the determination of cysteamine (CA) using promazine hydrochloride-modified multi-wall carbon nanotubes carbon paste electrode (PrH/MWCNTs CPE). Because of the good electrochemical activity of MWCNTs and the acceptable performance of promazine hydrochloride (PrH) as an electrocatalytic mediator, the modified electrode significantly enhanced the sensitivity for the detection of CA in comparison to the bare carbon paste electrode (CPE). All chemical parameters such as pH of solution, concentration of PrH and kinetic parameters of the system were investigated. Linear sweep voltammetric (LSV) method was used to follow the electrocatalytic effect of CA on the current–potential response of PrH. Under optimum conditions, the obtained net peak current ?I p(I sample???I blank) was linear with CA concentrations in two dynamic ranges of 2.0–346.5 μmol l?1 (?I p?=?(0.0195?±?0.0043)C CA?+?(0.7648?±?0.0397) (r 2?=?0.9948)) and 346.5–1,912.5 μmol l?1 (?I p?=?(0.0100?±?0.0026)C CA?+?(3.8981?±?0.0828) (r 2?=?0.9911)) with a detection limit of 0.8 μmol l?1. Finally, the PrH/MWCNTs CPE was successfully applied for the determination of CA in urine and drug samples with satisfactory results. 相似文献
9.
A sensitive electrochemical method was developed for the voltammetric determination of thymine at a composite film-modified electrode 1-phenyl-3-methyl-4-(2-furoyl)-5-pyrazolone (HPMαFP)/polypyrrole (Ppy)/glassy carbon electrode (GCE). The electrochemical parameters of thymine were investigated by cyclic voltammetry and differential pulse voltammetry. In pH?=?7.4, one sensitive oxidation peak of thymine with E pa?=?0.968 V was observed on the HPMαFP/PPy-modified electrode. The difference of peak potential (?E pa) was 188 mV lower than that for bare GCE. Compared to the bare GCE and Ppy/GCE, the HPMαFP/Ppy/GCE-modified electrode showed an excellent electrocatalytic effect on the oxidation of thymine and displayed a shift of the oxidation potential in the negative direction with significant increase in the peak current. Under the optimum condition, the concentration calibration range and detection limit are 2?×?10?6–1?×?10?4 and 4.85?×?10?7?M for thymine. This developed method had been applied to the direct determination of thymine in medical pipefish samples with satisfactory results. 相似文献
10.
Mohammad Mazloum-Ardakani Seyyed Hamid Ahmadi Zohal Safaei Mahmoudabadi Alireza Khoshroo Kourosh Tabar Heydar 《Ionics》2014,20(12):1757-1765
In the present paper, the use of a carbon paste electrode modified with 1-(4-(1, 3-dithiolan-2-yl)-6, 7-dihydroxy-2-methyl-6, 7-dihydrobenzofuran-3-yl)ethanone (DDE) and TiO2 nanoparticles prepared by a simple and rapid method was described. The modified electrode showed excellent properties for electrocatalytic oxidization of epinephrine (EP), acetaminophen (AC) and folic acid (FA). The apparent charge transfer rate constant, k s?=?1.14 s?1, and transfer coefficient, α?=?0.54, for electron transfer between the modifier and carbon paste electrode were calculated. It has been found that under optimum condition (pH?=?7.0) in cyclic voltammetry, the oxidation of EP occurs at a potential about 280 mV less positive than that of an unmodified carbon paste electrode. The values of transfer coefficients (α?=?0.46), catalytic rate constant (k?=?1.2?×?104 M?1 s?1) and diffusion coefficient (D?=?2.70?×?10?5 cm2 s?1) were calculated for EP. Differential pulse voltammetry (DPV) exhibited two linear dynamic ranges of 0.5 to 50.0 μM and 50.0 to 1,000 μM for EP. This modified electrode is quite effective not only for the detection of EP, AC and FA but also for the simultaneous determination of these species in a mixture. The limit of detection for EP, AC and FA is 0.10, 1.80 and 2.36 μM, respectively. 相似文献