Electrochemistry and voltammetric determination of colchicine using an acetylene black-dihexadecyl hydrogen phosphate composite film modified glassy carbon electrode

The electrochemical behavior of colchicine at an acetylene black-dihexadecyl hydrogen phosphate (denoted as AB-DHP) composite film coated glassy carbon electrode (GCE) was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). Compared with the poor electrochemical signal at the unmodified GCE, the electrochemical response of colchicine at the AB-DHP film modified GCE was greatly improved, as confirmed from the significant peak current enhancement. The remarkable peak current enhancement indicates that the AB-DHP modified GCE has great potential in the sensitive determination of colchicine. Thus, all the experimental conditions, which influence the electrochemical response of colchicine, were studied and the optimum conditions were achieved. Finally, a sensitive and simple voltammetric method with a good linear relationship in the range of 1.0 x 10(-7) approximately 4.0 x 10(-5) mol/L, was developed for the determination of colchicine. The detection limit of colchicine was also examined and a low value of 4.0 x 10(-8) mol/L for 4-min accumulation was obtained (S/N=3). This electrode was successfully applied to detect colchicine in human urine samples.     

微渗析活体取样与液相色谱安培检测法联用测定鼠脑中黄嘌呤和次黄嘌呤

采用微渗析活体取样技术和高效液相色谱安培检测法 ,测定了鼠脑纹状体中的黄嘌呤和次黄嘌呤。安培检测以玻碳电极为工作电极 ,检测电位为 0 .9V。在 5 .0× 1 0 - 7～ 1 .0× 1 0 - 4 mol/L浓度范围内 ,黄嘌呤和次黄嘌呤的浓度分别与峰电流呈良好的线性关系 ,检出限分别为 8 0× 1 0 - 8mol/L和 3 0× 1 0 - 7mol/L。该方法为生命科学的研究提供了一种新的分析手段     

Electrochemical behavior of phenol at acetylene black-dihexadecyl hydrogen phosphate composite modified glassy carbon electrode in the presence of cetyltrimethylammonium bromide

The electrochemical response of phenol at acetylene black (AB)-dihexadecyl hydrogen phosphate (DHP) composite modified glassy carbon electrode in the presence of cetyltrimethylammonium bromide (CTAB) was investigated. In this system, a sensitive oxidation peak at 0.62 V (SCE) was obtained. The electrode process and the influence of CTAB on the oxidation of phenol were explored by chronocoulometry and linear sweep voltammetry (LSV). Experimental conditions for the determination of phenol were optimized. In the range of 5.0 × 10⁻⁷ to 1.2 × 10⁻⁵ M, the phenol concentration was linear with the oxidation peak current and the detection limit was found to be 1.0 × 10⁻⁷ M for 3 min accumulation. The method was applied for the determination of phenol in lake water and the results were satisfactory. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 2, pp. 222–229. The text was submitted by the authors in English.     

Trace determination of zirconium by adsorptive anodic stripping voltammetry of its complex with alizarin violet using a glassy carbon electrode modified with acetylene black-dihexadecyl hydrogen phosphate composite film

We report on a novel electrochemical method for the sensitive determination of trace zirconium (Zr) at a glassy carbon electrode modified with a film of acetylene black containing dihexadecyl hydrogen phosphate and in the presence of alizarin violet (AV). The method is based on the preconcentration of the Zr(IV)-AV complex at a potential of ?200?mV (vs. SCE). The adsorbed complex is then oxidized, producing a response with a peak potential of 526?mV. Compared to the poor electrochemical signal at the unmodified GCE, the electrochemical response of Zr(IV)-AV complex is greatly improved, as confirmed by the significant increase in peak current. The effects of experimental conditions on the oxidation current were studied and a calibration plot established. The oxidation current is linearly related to the Zr(IV) concentration in the 8.0?pM to 10?nM concentration range (c_AV?=?0.2???M) and 10?nM ~0.6???M (c_AV?=?2.0???M), and the detection limit (S/N?=?3) is as low as 4.0?pM for a 3-min accumulation time. The method was successfully employed to the determination of zirconium in standard ore samples.

Electrochemical sensor using glassy carbon electrode modified with acylpyrazolone-multiwalled carbon nanotube composite film for determination of xanthine

In this work, an electrochemical sensor 1-phenyl-3-methyl-4-(2-furoyl)-5-pyrazolone/multiwalled carbon nanotubes/glassy carbon electrode (GCE) was prepared for the determination of xanthine (XN) in the presence of an excess of uric acid. Cyclic voltammetry and differential pulse voltammetry were used to characterize the electrode. The oxidation of XN occurred in a well-defined peak having E _p 0.73 V in phosphate buffer solution of pH 6.0. Compared with the bare GCE, the electrochemical sensor greatly enhanced the oxidation signal of XN with negative shift in peak potential about 110 mV. Based on this, a sensitive, rapid, and convenient electrochemical method for the determination of XN has been proposed. Under the optimized conditions, the oxidation peak current of XN was found to be proportional to its concentration in the range of 0.3~50 μM with a detection limit of 0.08 μM. The analytical utility of the proposed method was demonstrated by the direct assay of XN in urine samples and was found to be promising at our preliminary experiments.     

Simultaneous determination of uric acid, xanthine and hypoxanthine at poly(pyrocatechol violet)/functionalized multi-walled carbon nanotubes composite film modified electrode

A sensitive and selective electrochemical method was developed for simultaneous determination of uric acid (UA), xanthine (XA) and hypoxanthine (HX) based on a poly (pyrocatechol violet)/carboxyl functionalized multi-walled carbon nanotubes composite film modified electrode. The preparation and basic electrochemical performance of the novel composite film modified glassy carbon electrode were investigated in details. The electrochemical behaviors of UA, XA and HX at the modified electrode were studied by cyclic voltammetry. The results showed that this new electrochemical sensor exhibited excellent electrocatalytic activity towards the oxidation of the three analytes. The mechanism of catalysis was discussed. The anodic peaks of the three species were well defined with lowered oxidation potential and enhanced oxidation peak currents, so the modified electrode was used for simultaneous voltammetric measurement of UA, XA and HX by differential pulse voltammetry. Under the optimum conditions, the detection limits were 0.16 μmol L(-1) for UA, 0.05 μmol L(-1) for XA and 0.20 μmol L(-1) for HX, respectively (S/N of 3). The proposed method has been successfully applied to simultaneous determination of UA, XA and HX in human serum samples.     

乙炔黑修饰电极上吡虫啉的电化学行为及测定

制备了乙炔黑修饰电极(AB/GCE),并用循环伏安法(CV)研究了吡虫啉(IDP)在该修饰电极上的循环伏安行为。在pH 9.0的NH3.H2O-NH4Cl缓冲液中,IDP在该电极上出现一不可逆的还原峰。在20～240mV/s扫速范围内,其还原峰电流(Ipc)与扫速平方根(v1/2)呈线性关系,表明该电极过程受扩散控制。计算了电极过程的部分动力学参数:电极有效面积为0.0635cm2,转移电子数为2,扩散系数为3.793×10-3cm2/s。运用方波伏安法测定不同浓度IDP的方波伏安曲线,还原峰电流Ipc与IDP浓度在7.0×10-7～8.0×10-5mol/L范围内呈良好线性关系(r=0.9975),检出限为2.29×10-7mol/L,加标回收率为93.5%～105.3%。     

Voltammetric determination of nitrendipine on composite film modified electrode

This paper was focused on the use of electrochemical methods based on a novel composite film modified electrode for the pharmaceutical analysis. This modified electrode was fabricated by integration of room-temperature ionic liquids (1-butyl-3-methylimidazolium hexafluophosphate) and multi-walled carbon nanotubes with polymeric matrix (chitosan). This sensor showed good stability and high accumulation efficiency. Electrochemical behavior of nitrendipine at this electrode was investigated in detail. A sensitive cathodic peak was observed at −0.76 V on the modified electrode. Under the optimized conditions, the peak current was linear to nitrendipine concentration in the range of 4.0 × 10⁻⁷ ∼ 5.0 × 10⁻⁵ M, and the detection limit was estimated to be 1.0 × 10⁻⁷ M after an accumulation for 150 s on open circuit. In addition, the proposed method was applied to the determination of nitrendipine in real samples, and the recovery was from 97.6 to 102.5%.     

铜卟啉-L-半胱氨酸自组装复合膜修饰电极的制备及电化学性能研究

利用电化学扫描法在L 半胱氨酸(Cys)自组装单分子膜修饰金电极表面现场制备了金属卟啉复合膜,对其进行SEM和ATR FTIR表征。修饰电极的支持电解质以及pH值对膜的稳定性和灵敏度有很大影响。铜卟啉 L Cys膜对H2O2具有良好的电催化还原特性,催化电流与H2O2浓度在1 0×10 6到3 0×10 5mol·L 1范围内线性关系,相关系数0 9995,检测限达1 0×10 7mol·L 1。     

Simultaneous determination of uric acid, xanthine and hypoxanthine with an electrochemically pretreated carbon paste electrode

A simple method is presented for the simultaneous differential pulse voltammetric determination of uric acid, xanthine and hypoxanthine. It is based on the improved current responses of the three analytes at carbon paste electrodes polarized in a dilute alkaline medium (0.002 mol/l NaOH, 0.1 mol/l NaClO₄) at 1.3 V vs. SCE for a short time. Compared with the methods reported in the literature, this procedure has a much wider linear range (2 to 3 orders of magnitude in concentration), lower detection limits (5 to 10 g l^–1) and less interference by ascorbic acid. The electrochemical responses were found to be dependent on the pre-anodization potential and the time imposed on the electrodes as well as on the alkalinity of the supporting electrolyte. The proposed procedure was used to determine uric acid, xanthine and hypoxanthine in human urine without any preliminary treatment.     

Electrochemical determination of sulphide at multi-walled carbon nanotubes-dihexadecyl hydrogen phosphate composite film modified electrodes based on in situ synthesis of methylene blue

A novel electrochemical method for the determination of sulphide at a multi-walled carbon nanotube-dihexadecyl hydrogen phosphate composite film coated glassy carbon electrode （MWNTs-DHP/GCE） based on in situ synthesis of methylene blue （MB） was established. 2007 Sheng Shui Hu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

Electrochemical determination of theophylline on a glassy carbon electrode modified with reduced graphene oxide-sodium dodecyl sulfate-Nafion composite film

Russian Chemical Bulletin - An electrochemical sensor based on glassy carbon electrode modified with reduced graphene oxide-sodium dodecyl sulfate-Nafion* composite film was constructed and used to...     

对乙酰氨基酚在石墨烯/壳聚糖复合膜修饰电极上的电化学行为研究

制备了石墨烯-壳聚糖复合物修饰玻碳电极(GO/CS-GCE),考察了对乙酰氨基酚(APAP)在修饰电极上的电化学行为,发现石墨烯-壳聚糖复合物能较好改善玻碳电极对APAP的电化学性能,APAP在修饰电极上的电化学反应过程是受吸附控制的2电子,2质子反应过程;进一步研究发现在pH=9.16的碳酸钠-碳酸氢钠缓冲体系中,对...     

Electrochemical determination of methimazole based on the acetylene black/chitosan film electrode and its application to rat serum samples

A novel method has been developed for the determination of methimazole, which was based on the enhanced electrochemical response of methimazole at the acetylene black/chitosan composite film modified glassy carbon electrode. The electrochemical behavior of methimazole was studied at this film electrode by cyclic voltammetry and differential pulse voltammetry. The experimental results showed that methimazole exhibited a remarkable oxidation peak at 0.63V at the film electrode. Compared with the bare glassy carbon electrode, the oxidation peak current increased greatly, and the peak potential shifted negatively, which indicated that the acetylene black/chitosan film electrode had good catalysis to the electrochemical oxidation of methimazole. The enhanced oxidation current of methimazole was indebted to the nano-porus structure of the composite film and the enlarged effective electrode area. The influences of some experimental conditions on the oxidation of methimazole were tested and the calibration plot was examined. The results indicated that the differential pulse response of methimazole was linear with its concentration in the range of 1.0×10(-7) to 2.0×10(-5)mol/L with a linear coefficient of 0.998, and in the range of 4.0×10(-5) to 3.0×10(-4)mol/L with a linear coefficient of 0.993. The detection limit was 2.0×10(-8)mol/L (S/N=3). The film electrode was used to detect the content of methimazole in rat serum samples by the standard addition method with satisfactory results.     

Examination of performance of glassy carbon paste electrode modified with gold nanoparticle and xanthine oxidase for xanthine and hypoxanthine detection

A composite electrode was prepared by modifying glassy carbon microparticles with gold nanoparticles (Au-nps) and xanthine oxidase enzyme (XOD) for xanthine (X) and hypoxanthine (Hx) detection. After the optimization of the system for X, the biosensor was characterized for X and Hx. A linearity was obtained in the concentration range between 5.00 × 10⁻⁷ and 1.00 × 10⁻⁵ M for X with equation of y = 0.24x + 0.712 and 5.00 × 10⁻⁶ to 1.50 × 10⁻⁴ M for Hx, with equation of y = 0.014x + 0.575, respectively. Obtained results were compared to X and/or Hx biosensors including/not including Au-np in the structure. The developed system was also applied for detection of Hx in canned tuna fish sample and very promising results were obtained.     

Construction of biosensor for hypoxanthine determination by immobilization of xanthine oxidase and uricase in polypyrrole-paratoluenesulfonate film

Journal of Solid State Electrochemistry - A highly selective and stable amperometric biosensor for the determination of the hypoxanthine (Hx) molecule was designed in this study. For this purpose,...     

Electrochemical oxidation and detection of paeonol on modified electrode with acetylene black nanoparticles

With an aim to construct a sensing platform for the electrochemical detection of paeonol, we modified the glassy carbon electrode with acetylene black nanoparticle (AB). A sensitive oxidation peak of paeonol was observed with remarkably increased peak current on the modified electrode because the electrode has a big surface area due to three dimensional structure of AB nanoparticles. The optimization of detection conditions was performed, including pH value of the buffer, the amount of AB nanoparticles on the electrode surface, the accumulation potential and time of paeonol. Under the optimized conditions, the oxidation peak current of paeonol increased linearly with its concentration over the range from 5×10(-7) to 1×10(-4) M. The detection limit was calculated to be 1×10(-7) M. The modified electrode was successfully applied to detect the content of paeonol in cortex moutan, a common traditional Chinese medicine. The method is new, sensitive, rapid and convenient for the detection of paeonol.     

Simultaneous voltammetric determination of 2-nitrophenol and 4-nitrophenol based on an acetylene black paste electrode modified with a graphene-chitosan composite

We describe a simple and sensitive voltammetric method for the simultaneous determination of 2-nitrophenol and 4-nitrophenol. It is based on the use of an acetylene black paste electrode modified with a graphene-chitosan composite film (denoted as Gr-Chit/ABPE). The reduction peak currents of 2-nitrophenol (at ?252 mV) and of 4-nitrophenol (at ?340 mV) in pH 1.0 solution increase significantly at the Gr-Chit/ABPE in comparison to a bare ABPE. Factors affecting sensitivity were optimized and a linear relationship is found between peak current and the concentrations of 2-nitrophenol (in the 0.4 μM to 80 μM range) and for 4-nitrophenol (in the 0.1 μM to 80 μM range). The detection limits (at an SNR of 3 and after a 30-s accumulation time) are 200 nM for 2-nitrophenol and 80 nM for 4-nitrophenol, respectively. The modified electrode was successfully applied to the direct and parallel determination of 2-nitrophenol and 4-nitrophenol in spiked water samples.

Electrochemical behaviors of ofloxacin and its voltammetric determination at carbon nanotubes film modified electrode

A multi-wall carbon nanotubes (MWNTs)-Nafion film-coated glassy carbon electrode (GCE) was fabricated and the electrochemical behavior of ofloxacin on the MWNTs-Nafion film-coated GCE were investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current of ofloxacin increased significantly on the MWNTs-Nafion film modified GCE compared with that using a bare GCE. This nano-structured film electrode exhibited excellent enhancement effects on the electrochemical oxidation of ofloxacin. A well-defined oxidation peak attributed to ofloxacin was observed at 0.97 V and was applied to the determination of ofloxacin. The oxidation peak current was proportional to ofloxacin concentration in the ranges 1.0 × 10⁻⁸ to 1.0 × 10⁻⁶ mol/L and 1.0 × 10⁻⁶ to 2.0 × 10⁻⁵ mol/L. A detection limit of 8.0 × 10⁻⁹ mol/L was obtained for 400 s accumulation at open circuit (S/N = 3). This method for the detection of ofloxacin in human urine was satisfactory. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 24(5): 540–545 [译自: 应用化学]     

Electrochemical oxidation and determination of methylparaben at overoxidized polypyrrole film modified a boron-doped diamond electrode

Electrochemical oxidation of methylparaben (MP) is studied on an overoxidized polypyrrole (OPPy)-modified boron-doped diamond electrode using the cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. The OPPy-modified BDD electrode displays the catalytic activity of electrooxidation of methylparaben. The modification of BDD electrode surface results in higher values of recorded oxidation currents of the methylparaben than on a bare BDD electrode. The diffusion character of recorded current is determined on the basis of the relation between the current and the scan rate. The linear relationship between methylparaben oxidation peak current is obtained in the range 1.57?×?10^??6–2.06?×?10^??5 mol L^??1. A new voltammetric procedure is proposed to quantify methylparaben in cosmetic products using an overoxidized polypyrrole (OPPy)-modified BDD electrode. The results are compared to the HPLC technique described in the literature as the reference method.