共查询到20条相似文献,搜索用时 10 毫秒
1.
Sh. Lü 《Russian Journal of Electrochemistry》2006,42(2):163-166
A glassy-carbon electrode modified with a thin film of multiwall carbon nanotubes is used for the determination of nicotinic
acid (NA). At the electrode, the latter yields a well-defined and very sensitive oxidation peak at 0.21 V (SCE). Investigation
of the electrochemical behavior of NA shows that the electrode significantly enhances the NA oxidation peak current, compared
with the non-modified electrode. Based on this, a very sensitive and simple electrochemical method is proposed for the NA
determination after the optimization of all experimental parameters. The oxidation peak current is proportional to the NA
concentration over the range 2×10−7 to 4×10−5 M, and the detection limit is 8×10−8 M after a 4-min accumulation. The relative standard deviation of 5.4% for the successive determination of 1×10−6 MNA (n=10) indicates excellent reproducibility. The analysis method is successfully demonstrated using tablet samples.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 2, pp. 190–195.
The text was submitted by the author in English. 相似文献
2.
A modified electrode, based on a hexadecane (C(16))-coated glassy-carbon electrode (GCE) has been developed for the determination of parathion. The electrochemical behavior of parathion was investigated by cyclic voltammetry (CV). The peak potential and peak current were found to depend on the supporting electrolyte and the pH of the buffer solution. The reduction currents for parathion were proportional to parathion concentration over the range 8x10(-8)-2x10(-5) mol L(-1). The detection limit was 2x10(-8) mol L(-1) parathion for an accumulation time of 30 s. The effects of organic and inorganic species on the determination of parathion were also studied. A procedure was developed to extract parathion from spiked soil samples using a mixture of dichloromethane and acetone as the extraction solvent. The complete extraction and analytical procedure are simple, inexpensive and rapid. Parathion was determined in a soil sample by use of linear scan voltammetry (LSV). 相似文献
3.
Conditions have been found for the determination of benzidine, o-tolidine, o-dianisidine, 3,3'-diaminobenzidine and 3,3'-dichlorobenzidine by classical and differential pulse voltammetry at a glassy-carbon stationary or rotating electrode, in the concentration range 10(-5)-10(-3)M. The mechanism of the oxidation is discussed and applications are presented for the determination of these chemical carcinogens and their mixtures either directly, or after preliminary separation by extraction or thin-layer chromatography. 相似文献
4.
通过循环伏安法(CV)将苯胺(AN)-邻氨基酚(OAP)修饰在玻碳电极(GCE)表面,制备出聚苯胺-邻氨基酚聚合物膜修饰电极(PAN-OAP/GCE),并用该电极对抗坏血酸(AA)进行测定。分别对OAP与AN聚合浓度比和磷酸缓冲溶液(PBS)pH进行优化。结果表明OAP与AN浓度比为1:14,pH为6.80时,所得聚合物膜修饰电极具有良好的电化学催化活性和稳定性。同时,在0.1 mol/L PBS(pH 6.80)中,采用差分脉冲伏安法(DPV)对AA进行测定,结果表明PAN-OAP/GCE电极对AA具有明显的电化学催化氧化作用,且AA在膜修饰电极上的响应电流和其浓度在1.50×10-8~2.12×10-6mol/L范围内呈良好的线性关系,线性回归方程为ip=1.0344c+0.0183,相关系数为0.9988。检测限可达5.0×10-9mol/L。该修饰电极具有较高的灵敏度和选择性,用于样品中AA的检测,回收率为96.0%~101.2%。 相似文献
5.
Yueqin Fan Lifang Fan Shuangming Meng Yong Guo Yongwen Liu 《Journal of Analytical Chemistry》2012,67(4):370-377
Cobalt hydroxide film modified electrode was prepared by depositing cobalt hydroxide on glassy carbon electrode (GCE) surface in an alkaline aqueous solution and then characterized by cyclic voltammetry. The electrochemical behavior of resorcin
on the film modified electrode was investigated. The results show that cobalt hydroxide films in alkaline solutions have good
electrocatalytical activity towards the oxidation of resorcin. The recovery of resorcin from sample ranged from 95.2 to 103.4%
and the oxidation peak currents were directly proportional to the resorcin concentration from 5.0 × 10−6 to 1.05 × 10−4 M with correlation coefficient of 0.9986. A detection limit of 1.0 × 10−7 M for resorcin was estimated. Various factors affecting the electrocatalytical activity of cobalt hydroxide film were investigated
in detail. Real water samples were analyzed and satisfactory results were obtained. 相似文献
6.
在室温条件下,利用恒电位吸附法和多电位阶跃法制备了金-铂纳米粒子(Au-PtNPs)/单壁碳纳米管(SWNT)复合材料修饰电极,并利用电化学方法和原子力显微镜(AFM)对其进行了表征。结果表明:Au-Pt-NPs可很好的结合在SWNT表面,在该电极的最佳修饰条件下(SWNT分散液中电沉积30 s,H2PtO6中浸泡10 min,循环阶跃沉积金纳米粒子45次(葡萄糖)或30次(甲醇))可以较好的电催化氧化碱性环境中的葡萄糖及甲醇,有望在葡萄糖无酶传感器及甲醇燃料电池中得到应用。 相似文献
7.
8.
9.
Y. Z. Song F. X. Zhu Y. Song J. F. Zhou X. Z. Chu F. Y. Wu A. F. Zhu C. M. Wei J. Song X. Li J. Xu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(1):80-83
A sensor based on gold nanoparticle on the surface of L-cysteine modified gold electrode is prepared. Electrochemical behavior of dopamine hydrochloride is investigated. The linear relation between peak current of dopamine hydrochloride and scan speed in the range of 10 to 1000 mV s?1 indicates that a diffusion-adsorption controls the process. The linearity range is 1.05 × 10?5–7.38 × 10?4 M with detection limit of 1.05 × 10?6 M. The recoveries were in the range from 99.8 to 101.5% with relative standard deviations of 1.3 ~ 2.3% (n = 6). The modified electrode under ambient conditions over a period of 2 weeks has an excellent repeatability and reproducibility. 相似文献
10.
V. A. Nevostruev I. K. Kilina O. N. Bulgakova Yu. I. Ivanov 《Journal of Analytical Chemistry》2000,55(1):70-71
The effect of the electrochemical pretreatment of the surface of a glassy-carbon indicator electrode on the electrode response
and the repeatability of measurements in the stripping voltammetric determination of lead was studied. It was shown that the
analytical signal depends on the nature of an electrolyte used for the pretreatment. The electrolytes that gave the most satisfactory
results in the pretreatment were proposed 相似文献
11.
In this paper, multi-walled carbon nanotubes (MWCNTs) were successfully immobilized on the surface of a glassy carbon electrode by mixing with horse-radish peroxidase (HRP). The electrochemical behavior of H2O2 was also studied with the MWCNTs-HRP modified electrode as a working electrode. The MWCNTs-HRP modified electrode showed excellent response of reduction current for the determination of H2O2 at the potential of -300 mV (vs. Ag/AgCl). We assembled the MWCNTs-HRP modified electrode in a thin-layer flow cell and the H2O2 solution was continuously introduced into the cell with a syringe pump. We optimized the sensitivity of the H2O2 sensor by adjusting the working potential and the pH of the buffer solution. The peak current increased linearly with the concentration of H2O2 in the range 3.0 x 10(-7) to approximately 2.0 x 10(-4) mol L(-1). The detection limit is 1.0 x 10(-7) mol L(-1) (S/N = 3). The interferences from ascorbic acid, uric acid and other electroactive substances can be greatly excluded since the sensor can be operated at -300 mV. Stability and reproducibility of the MWCNTs-HRP chemically modified electrode were also studied in this paper. Fabricated with glucose and lactate oxidase, the MWCNTs-HRP electrode was also applied to prepare the on-line glucose and lactate biosensors because of the high sensitivity for the determination of H2O2. 相似文献
12.
The dispersion of alumina particles on a glassy-carbon surface serving as a modified electrode significantly enhances the amperometric detection of cysteine and glutathione following liquid chromatography. With an applied potential of 0.8 V vs. SCE, the detection limits were 1.2 ng for cysteine and 8 ng for glutathione and the electrode response was linear up to 600 ng for cysteine and 1.8 mug for glutathione. The modified electrode displayed high sensitivity and stability and was easy and inexpensive to prepare. 相似文献
13.
The anodic-stripping voltammetric behaviour of arsenic(III) at a glassy-carbon electrode copper-coated in situ has been investigated. The effects of copper concentration, acidity, deposition potential and sweep rate on the stripping peak have been examined and criteria are given for the choice of experimental conditions. The procedure is applicable to the determination of 7.5-750 ng/ml of arsenic levels and is useful for the analysis of various types of water sample. 相似文献
14.
Yazhen Wang 《Mikrochimica acta》2011,172(3-4):419-424
The electrochemistry of uric acid at a gold electrode modified with a self-assembled film of L-cysteine was studied by cyclic voltammetry and differential pulse voltammetry. Compared to the bare gold electrode, uric acid showed better electrochemical response in that the anodic peak current is stronger and the peak potential is negatively shifted by about 100 mV. The effects of experimental conditions on the oxidation of uric acid were tested and a calibration plot was established. The differential pulse response to uric acid is linear in the concentration range from 1.0?×?10?6 to ~?1.0?×?10?4 mol?L?1 (r?=?0.9995) and from 1.0?×?10?4 to ~?5.0?×?10?4 mol?L?1 (r?=?0.9990), the detection limit being 1.0?×?10?7 mol?L?1 (at S/N?=?3). The high sensitivity and good selectivity of the electrode was demonstrated by its practical application to the determination of uric acid in urine samples.
Cyclic voltammograms of UA at the bare electrode (a,b) and the L-Cys/Au electrode (c,d,e) in HAc-NaAc buffer containing different concentrations of UA. (a,c): blank; (b, d): 2.0?×?10?5 mol?L?1; (e) 4.0?×?10?5 mol?L?1. Scan rate: 100 mV?s?1 相似文献
15.
16.
17.
18.
制备了一种新颖的Nation-离子液体一多壁碳纳米管复合膜修饰电极,并研究了抗坏血酸(AA)、多巴胺(DA)和尿酸(uA)在该修饰电极上的电化学行为.该修饰电极结合了多壁碳纳米管良好的导电性、离子液体优良的催化性能及Nation的高选择性等优点,对AA、DA和UA的氧化具有很好的催化和分离效果,实现了AA、DA和UA的同时测定.在三者共存体系中,AA和DA、DA和UA的氧化峰电位差分别为148和167mV.对AA、DA和UA的同时检测,线性范围分别为5-3200、1~1100和1-300gmol/L,检出限分别为1.66、0.33和0.33gmol/L.该修饰电极选择性好、稳定性高、重现性好,有望用于实际样品中AA、DA和UA的同时检测. 相似文献
19.
A benzoquinone modified basal plane pyrolytic graphite electrode shows electrocatalytic activity for the oxidation of NADH and ascorbic acid in phosphate buffer (pH 7.3). The modified electrode shows a linear variation of catalytic current with concentration in the range 1-10 mM for both NADH and ascorbic acid. The rate constants have been estimated from the surface coverage data. 相似文献
20.
Phytic acid (PA) with its unique structure was attached to a glassy carbon electrode (GCE) to form PA/GCE modified electrode which was characterized by electrochemical impedance. The electrochemical behavior of cytochrome c (Cyt c) on the PA/GCE modified electrode was explored by cyclic voltammetry and differential pulse voltammetry. The Cyt c displayed a quasi-reversible redox process on PA modified electrode pH 7.0 phosphate buffer solution with a formal potential (E 0′) of 57 mV (versus Ag/AgCl). The peak currents were linearly related to the square root of the scan rate in the range of 20–120 mV·s?1. The electron transfer rate constant was determined to be 12.5 s?1. The PA/GCE modified electrode was applied to the determination of Cyt c, in the range of 5?×?10?6 to 3?×?10?4 M, the currents increase linearly to the Cyt c concentration with a correlation coefficient 0.9981. The detection limit was 1?×?10?6 M (signal/noise?=?3). 相似文献