摘要：
A graphene oxide (GO) film coated glassy carbon electrode (GCE) was fabricated for sensitive determination of 4-nitrophenol (4-NP). The GO-based sensor was characterized by scanning electron microscope, atomic force microscopy and electrochemical impedance spectroscopy. The electrochemical behaviors of 4-NP at the GO-film coated GCE were investigated in detail. In 0.1 M acetate buffer with a pH of 4.8, 4-NP yields a very sensitive and well-defined reduction peak at the GO-modified GCE. It is found that the GO film exhibits obvious electrocatalytic activity toward the reduction of 4-NP since it not only increases the reduction peak current but also lowers the reduction overpotential. Based on this, an electrochemical method was proposed for the direct determination of 4-NP. Various kinetic parameters such as transfer electron number, transfer proton number and standard heterogeneous rate constant were calculated, and various experimental parameters were also optimized. Under the optimal conditions, the reduction peak current varies linearly with the concentration of 4-NP ranging from 0.1 to 120 mu M, and the detection limit is 0.02 mu M at the signal noise ratio of 3. Moreover, the fabricated sensor presented high selectivity and long-term stability. This electrochemical sensor was further applied to determine 4-NP in real water samples, and it showed great promise for simple, sensitive, and quantitative detection of 4-NP. (C) 2011 Elsevier B.V. All rights reserved.
摘要：
A novel and convenient electrochemical method has been developed for sensitive determination of melamine (MEL) using ascorbic acid (AA) as the recognition element. The working electrode employed in this method was modified with the nanocomposite of hydroxyapatite/carbon nanotubes to enhance the current signal of recognition element. The interaction between MEL and AA was investigated by fourier transform infrared spectroscopy and cyclic voltammetry, and the experimental results indicated that hydrogen bonding was formed between MEL and AA. Because of the existing hydrogen bonding and electrostatic interaction, the anodic peak current of AA was decreased obviously while the non-electroactive MEL added in. It illustrated that the MEL acted as an inhibitor to the oxidation of AA and the decreasing signals can be used to detect MEL. Under the optimal conditions, the decrease in anodic peak current of AA was proportional to the MEL concentrations ranging from 10 to 350 nM, with a detection limit of 1.5 nM. Finally this newly-proposed method was successfully employed to detect MEL in infant formula and milk, and good recovery was achieved.
期刊：
Sensors and Actuators B-Chemical,2012年168:381-389 ISSN：0925-4005
通讯作者：
Deng, Peihong
作者机构：
[Deng, Peihong; Xu, Zhifeng; Li, Junhua; Feng, Yonglan] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
通讯机构：
[Deng, Peihong] H;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
关键词：
p-Nitrophenol;Salicylaldehyde-modified chitosan;Acetylene black paste electrode;Voltammetric determination
摘要：
A novel method has been developed for the determination of p-nitrophenol (p-NP), which was based on the enhanced electrochemical response of p-NP at an acetylene black paste electrode coated with salicylaldehyde-modified chitosan (denoted as S-CHIT/ABPE). In 0.2 mol L−1 HCl solution, p-NP yielded a sensitive reduction peak at −0.348 V. Compared with the poor response at conventional carbon paste electrode, S-CHIT/ABPE remarkably increased the peak current of p-NP. All the experimental conditions, which influence the electrochemical response of p-NP, were studied and the optimum conditions were achieved. Finally, a sensitive and simple voltammetric method with a good linear relationship in the range of 8.0 × 10−8 mol L−1 to 2.0 × 10−6 mol L−1 was developed for the determination of p-NP. The detection limit (S/N = 3) was also examined and a low value of 3.0 × 10−8 mol L−1 for 120 s accumulation was obtained. The method has been successfully applied to the determination of p-NP in water samples with good recovery in the range of 96–104%.
摘要：
The combination of CuI, an oxime, and Bu4NI is successfully applied as a catalytic system for the N-arylation of imidazoles (I) and (VI), benzimidazole (IV), pyrazole (IX), and triazole (XII).
作者：
Li Jun-Hua*;Kuang Dai-Zhi;Feng Yong-Lan;Liu Meng-Qin
期刊：
分析化学,2011年39(12):1864-1870 ISSN：0253-3820
通讯作者：
Li Jun-Hua
作者机构：
[Feng Yong-Lan; Kuang Dai-Zhi; Li Jun-Hua; Liu Meng-Qin] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;[Feng Yong-Lan; Kuang Dai-Zhi; Li Jun-Hua; Liu Meng-Qin] Hengyang Normal Univ, Hunan Prov Coll, Key Lab Funct Organometall Mat, Hengyang 421008, Peoples R China.
通讯机构：
[Li Jun-Hua] H;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
期刊：
Asian Journal of Chemistry,2011年23(11):4959-4964 ISSN：0970-7077
通讯作者：
Kuang, Dai-Zhi
作者机构：
[Kuang, Dai-Zhi; Feng, Yong-Lan; Li, Jun-Hua; Liu, Meng-Qin] Hengyang Normal Univ, Dept Chem & Mat Sci, Coll Key Lab Funct Organometall Mat Hunan Prov, Hengyang 421008, Peoples R China.
通讯机构：
[Kuang, Dai-Zhi] H;Hengyang Normal Univ, Dept Chem & Mat Sci, Coll Key Lab Funct Organometall Mat Hunan Prov, Hengyang 421008, Peoples R China.
关键词：
Adsorptive stripping voltammetry;Aluminum;Eriochrome blue black R;Indium;Simultaneous determination
摘要：
A sensitive and selective method for the simultaneous determination of trace amounts of indium and aluminum by adsorptive stripping voltammetry was developed using Eriochrome blue black R [1-(2-hydroxy-1-naphthylazo)-2-naphthol- 4-sulfonic acid sodium salt, EBBR] as selective complexing agent on the multi-walled carbon nanotubes (MWCNTs) modified electrode. In a single scan, both metals gave peaks that were distinctly separated by 0.67 V allowing their determination in the presence of each other. Optimal analytical conditions were found to be: Eriochrome blue black R concentration of 40 μM, pH of 6.0 and adsorptive potential of-1.0 V versus saturated calomel electrode (SCE). With an accumulation time of 30 s, the peak currents are proportional to the concentration of indium in the range of 5.0 × 10-9 to 1.0 × 10-6 M and to that of aluminum in the range of 1.0 × 10-8 to 8.0 × 10-7 M. The detection limits (S/N = 3) are 1.0 × 10-9 and 8.0 × 10-9 M, respectively. This procedure was applied to simultaneous determination of indium and aluminum in some real samples with satisfactory results.
