Indirect Determination of Trace Copper(II) by Adsorptive Stripping Voltammetry with Zincon at a Carbon Paste Electrode

Traces of copper(II) can be determined by adsorptive stripping voltammetry using 2‐carboxy‐2′‐hydroxy‐5′‐sulfoformazyl benzene (Zincon) as complex forming reagent. First in phosphate buffer pH 6.4, copper(II)‐Zincon complex was adsorbed on carbon paste electrode (CPE) with an accumulation potential of 0.6 V. Following this, adsorbed complex was oxidized and detected by differential pulse voltammetric (DPV) scan from 0.6 to 1.0 V. The effective parameters in sensor response were examined. The detection limit (DL) of copper(II) was 1.1 μg/L and relative standard deviations (RSDs) for 10 and 200 μg/L Cu(II) were 1.81 and 1.03%, respectively. The calibration curve was linear for 2–220 μg/L copper(II). The resulting CPE does not use mercury and therefore, has a positive environmental benefit. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amount of copper in water and human hair samples.     

Determination of Trace Copper by Adsorptive Voltammetry Using a Multiwalled Carbon Nanotube Modified Carbon Paste Electrode

A new method for the determination of trace copper was described. A multiwalled carbon nanotube modified carbon paste electrode was prepared and the adsorptive voltammetric behavior of copper‐alizarin red S (ARS) complex at the modified electrode was investigated. By use of the second‐order derivative linear sweep voltammetry, it was found that in 0.04 mol/L acetate buffer solution (pH 4.2) containing 4×10^?6 mol/L ARS, when accumulation potential is 0 mV, accumulation time is 60 s and scan rate is 100 mV/s, the complex can be adsorbed on the surface of the electrode, yielding one sensitive reduction peak at ?172 mV (vs. SCE). The peak current of the complex is proportional to the concentration of Cu(II) in the range of 2.0×10^?11–4.0×10^?7 mol L^?1 with a detection limit (S/N=3) of 8.0×10^?12 mol/L (4 min accumulation). The proposed method was successfully applied to the determination of copper in biological samples with satisfactory results, the recoveries were found to be 96%–102%.     

碳糊电极阳极吸附伏安法测定大黄酸

在pH4.2的HAc-NaAc底液中,大黄酸在碳糊电极(CPE)上有一灵敏的吸附氧化峰,峰电位为1.14V(vs.SCE)。该氧化峰的二阶导数峰电流与大黄酸的浓度在8.0×10-9~8.0×10-7mol/L(富集120s)范围内呈良好的线性关系(r=0.998),检出限为2×10-9mol/L(S/N=3,富集180s)。探讨了大黄酸在CPE上的伏安性质和电极反应机理,并将本法应用于中药大黄中的大黄酸的测定,结果良好。     

奥美拉唑在碳糊电极上的吸附伏安测定法研究

研究了奥美拉唑在碳糊电极上的电化学行为及检测方法 ;在1.2mol·L -1H2SO4 底液中 ,通过富集用碳糊电极吸附伏安法测定奥美拉唑 ;阴极峰电位为0.403V(vsSCE) ,峰电流与奥美拉唑的浓度在7.8×10-8～3.7×10-5 mol·L-1 范围内呈良好的线性关系 ;该法的检出限为1.43×10-8 mol·L-1;用标准加入法测得回收率范围为94 %～102 % ;对奥美拉唑胶囊用该法进行了测定 ,获得了满意的结果 ;该法的优点是成本低 ,操作方便 ,重复性好及检出限较低 ;对电极响应机理进行了探讨 ,奥美拉唑的电极过程是一个两电子两质子的准可逆过程     

ZrC-桑色素络合物在碳糊电极上的二次导数吸附伏安法测定Zr的研究

研究了Zr 桑色素络合物在碳糊电极正电位区的吸附伏安行为 ,并利用其在 0 .74V处的二次导数吸附氧化峰电流与Zr(Ⅳ )浓度为 6 .0× 10 -9～ 2 .0× 10 -6mol/L呈线性而测定Zr;检出限为 3.0× 10 -9mol/L(S/N =3)。最佳测定条件为 :2 .0mol/LHCl、1.0× 10 -5mol/L桑色素 ;富集电位为 0V(vs .SCE) ;扫描速度为2 5 0mV/s。该法不需萃取分离 ,可直接用于岩石样品中Zr的测定 ,结果满意     

秋水仙碱在碳糊电极上的吸附伏安行为

秋水仙碱在硫酸溶液中加热水解得分析试液。在０．０５ｍｏｌ／ＬＨ２ＳＯ４底液中，用碳糊电极吸附伏安法测定秋水仙碱，阳性峰电位为０．８２Ｖ（ｖｓ．ＳＣＥ），峰电流与秋水仙碱的浓度在１．０×１０＾－７～１．０×１０＾－４ｍｏｌ／Ｌ范围内呈良好线性关系，检测下限为５．０×１０＾－８ｍｏｌ／Ｌ回收范围为９５．０％～１０３．５％ＲＳＤ为２．８％（ｎ＝１０）。本对反应机理进行了初步探讨。     

槲皮素化学修饰碳糊电极吸附溶出伏安法测定痕量铅

建立了用槲皮素修饰碳糊电极测定痕量铅的新方法 ,在 0 .1 0mol L甲酸盐缓冲液 (pH 4.3 )中 ,于 -0 .1 0V(vs.SCE)搅拌富集 ,再在 -0 .70V静止还原 40s后 ,阳极化扫描 ,于 -0 .42V左右获得一灵敏的铅阳极溶出峰。在最佳条件下 ,富集不同时间 ,其二次导数峰电流与Pb2 + 在 1 .0× 1 0 - 8～ 8.0× 1 0 - 7mol L和 2 .0× 1 0 - 9～ 6.0× 1 0 - 8mol L两个范围内呈线性关系 ,检出限为 8.0× 1 0 - 1 0 mol L(S N =3 )。同时初步探讨了电极反应机理。     

邻苯三酚红修饰碳糊电极吸附伏安法测定痕量铋

报道了采用邻苯三酚红修饰碳糊电极测定痕量铋的方法。在０．３０ｍｏｌ／Ｌ的ＨＣｌ溶液中,于－０．１０Ｖ搅拌富集３ｍｉｎ,然后在－０．３５Ｖ静止还原６０ｓ,再进行阳极化扫描,在－０．１０Ｖ左右获得灵敏的铋溶出峰,二次导数民流与铋浓度在１．０＊１０＾－９－６．０＊１０＾－７ｍｏｌ／Ｌ范围内呈线性关系,同限为５＊１０＾－１０ｍｏｌ／Ｌ。对电极反应机理进行了讨论。     

茜素紫修饰碳糊电极阳极溶出伏安法测定痕量锡

研究了利用茜素紫修饰碳糊电极测定痕量锡的阳极溶出伏安法。在 0 1 5mol/L醋酸盐缓冲溶液 (pH 4 .8)中 ,通过开路富集 ,Sn 和茜素紫形成络合物富集于电极表面 ,然后经过介质交换至 3 0mol/L的盐酸溶液中 ,于 -0 .80V还原后再进行阳极化扫描 ,于 -0 .68V左右获得一灵敏的锡的溶出峰。二次导数峰电流与Sn 浓度在 8.4× 1 0 -9～ 1 .4× 1 0 -6mol/L范围内呈良好的线性关系。检出限达 4×1 0 -9mol/L ,同时对电极反应机理进行了讨论。     

溴邻苯三酚红修饰碳糊电极吸附伏安法测定痕量锑

研制了溴邻苯三酚红(BPR)作修饰剂的碳糊修饰电极,并采用所制备的电极做工作电极建立了测定锑的方法。测定了电活性络合物的组成,并探讨了电极反应机理。该方法已用于锌电解液中痕量锑的测定,结果满意,检出限为2.0×10-8 mol/L。     

Determination of Copper(II) Through Anodic Stripping Voltammetry in Tartrate Buffer Using an Antimony Film Screen-printed Carbon Electrode

The voltammetric performance of an in situ plated antimony film screen-printed carbon electrode in hydrochloric acid, acetate buffer, and tartrate buffer was evaluated for the detection of copper(II) with differential pulse anodic stripping voltammetry. The tartrate buffer was superior, providing high sensitivity and good separation of copper and antimony stripping peaks. The analytical conditions for the determination of copper(II) were optimized. The detection limit was estimated to be 0.14?µg?L^?1 copper(II) and the relative standard deviation for 2.5?µg?L^?1 copper(II) was 3%. The applicability of the method was illustrated by the analysis of soil conditioner samples.     

Discrimination of Beers by Cyclic Voltammetry Using a Single Carbon Screen-printed Electrode

A fast, simple and costless methodology without sample pre-treatment is proposed for the discrimination of beers. It is based on cyclic voltammetry (CV) using commercial carbon screen-printed electrodes (SPCE) and includes a correction of the signals measured with different SPCE units. Data are submitted to partial least squares discriminant analysis (PLS−DA) and support vector machine discriminant analysis (SVM−DA), which allow a reasonable classification of the beers. Also, CV data from beers can be used to predict their alcoholic degree by partial least squares (PLS) and artificial neural networks (ANN). In general, non-linear methods provide better results than linear ones.     

Determination of Caffeine Using a Simple Graphite Pencil Electrode with Square-Wave Anodic Stripping Voltammetry

A simple commercial graphite pencil electrode (GPE) was utilized for monitoring caffeine using the square-wave anodic stripping voltammetry (SWASV) method. This method was applied to determine the caffeine levels in several tea samples, which yielded a relative error of 1% in the concentrations. Caffeine was deposited at 0.0V (vs. Ag/AgCl), then reduced at +1.40V to strip it on the GPE. Optimal experimental conditions for the analysis were found to be as follows: pH value of 9 for the medium; deposition potential of 0.0V; deposition time of 120s; SW frequency of 25Hz; SW amplitude of 45mV, and step potential of 6mV. Given these optimum conditions, a linear range was observed within the concentration of 0500mgL^–1. At caffeine concentrations of 50.0, 250.0, and 500.0mgL^–1, the relative standard deviations in measured concentrations (n=12) were 0.19, 0.09, and 0.11%, respectively. The detection limit was found to be 9.2mgL^–1, which is comparable with the result obtained using a carbon paste electrode, equivalent to 8.2mgL^–1.     

Determination of Trace Tin by Anodic Stripping Voltammetry at a Carbon Paste Electrode

A sensitive and selective procedure for the determination of trace tin at a carbon paste electrode was described. Each measurement cycle consisted of three steps: accumulation, reduction and stripping. The tin complex with bromopyrogallol red (BPR) was accumulated on the electrode surface in 0.10 mol/L acetate buffer (pH 4.5). After electrochemical reduction of Sn(II) had been carried out, the reoxidation wave of Sn(0) appeared at ?0.69 V (vs. SCE) on scanning the potential in the positive direction in 4.0 mol/L HCl. For a preconcentration time of 2 min, the detection limit was 0.06 μg/L (5×10^?10 mol/L ) and the linear range was from 0.1 to 50 μg/L. The proposed method was applied to the determination of tin in canned food and waste water samples with satisfactory results.     

Determination of Trace Vanadium by Adsorptive Stripping Voltammetry at a Carbon Paste Electrode

A method for the voltammetric determination of vanadium using a carbon paste electrode (CPE) was described. The new procedure is based on the adsorptive accumulation of the V(V)‐alizarin red S(ARS) complex onto the surface of the CPE, followed by the electrochemical reduction of adsorbed species. The optimal experimental conditions include the use of 0.10 mol/L acetate buffer (pH 5.1), 1.0×10^?5 mol/L ARS, an accumulation potential of ?0.10 V (versus SCE), an accumulation time of 2 min, a scan rate of 200 mV/s and a second‐order derivative linear scan mode. The reduction peak for the complex appears at ?0.52 V. The peak current is proportional to the concentration of V(V) over the range of 0.10–15.0 μg/L, and the detection limit is 0.04 μg/L for a 2 min adsorption time. The relative standard deviations(n=8) for 2.0 and 0.50 μg/L V(V) are 3.1 and 4.7%, respectively. The proposed method was applied to the determination of vanadium in water samples.     

Electrochemical Determination of Capsaicin and Silymarin Using a Glassy Carbon Electrode Modified by Gold Nanoparticle Decorated Multiwalled Carbon Nanotubes

The goal of this study was to develop a suitable electroanalytical method for the determination of primary compounds in the extracts of capsaicin and silymarin. For this purpose, a glassy carbon electrode immobilized with multiwalled carbon nanotubes decorated with gold nanoparticles was characterized by high resolution transmission electron microscopy and attenuated total reflectance infrared spectroscopy. The developed electrochemical sensor had a linear dynamic range from 0.15 to 35.0 µM. In addition, the limits of quantification for silymarin and capsaicin with the gold nanoparticle decorated multiwalled carbon nanotubes were 0.1564 and 0.2761 µg L^?1 with relative standard deviations (n = 3) of 1.65% and 2.09% and equivalent mass percentages of 93.33% and 62.02%, respectively. The methodology may be employed for the determination of capsaicin and silymarin in pharmaceutical and food products.     

碳糊电极吸附伏安法测定痕量钒

研究了钒 荧光镓(LMG)络合物在碳糊电极上的吸附伏安行为,发现其在+0.81V(vs.SCE)的阳极二次导数峰电流与钒(V)的浓度在一定范围内呈线性关系。在pH=4.3的0.26mol/L的HAc NH4Ac缓冲溶液中,于+0.4V富集,从+0.4至+1.4V以300mV/s线性扫描,方法线性范围为4.0×10-9～1.0×10-7mol/L(5.0×10-7mol/LLMG)和1.0×10-7～1.2×10-6mol/L(2.0×10-6mol/LLMG),检出限为1.0×10-9mol/L(S/N=3)。该法用于煤飞灰,粉煤灰和水样中钒的测定,结果满意。     

用聚吡咯修饰碳糊电极测定食盐中碘

在碱性条件下 ,利用还原剂硫酸肼将加碘盐中碘酸根离子还原成碘负离子 ,在饱和氯化钠溶液介质中 ,用聚吡咯修饰碳糊电极 ,采用差分脉冲伏安法测定碘离子,峰电位Ep = 0.409V(vs.SCE),峰电流与碘负离子浓度有良好线性关系 ,线性范围6.0×10-5 ～2.2×10-3 mol/L,检出限2.0×10-5 mol/L ,并对实际样品进行了回收率测定 ,取得较好结果。该法具有快速、灵敏、高效、简单的特点。     

Catalytic Adsorptive Stripping Voltammetry at a Carbon Paste Electrode for the Determination of Amiodarone

Voltammetry using solid electrodes usually suffers from the contamination due to the deposition of the redox products of analytes on the electrode surface. The contamination has resulted in poor reproducibility and overelaborate operation procedures. The use of the chemical catalysis of oxidant on the reduction product of analyte not only can eliminate the contamination of analyte to solid electrodes but also can improve the faradaic response of analyte. This work introduced both the catalysis of oxidant K2S2O8 and the enhancement of surfactant Triton X-100 on the faraday response of amiodarone into an adsorptive stripping voltammetry at a carbon paste electrode for the determination of amiodarone. The method exhibits high sensitivity, good reproducibility and simple operation procedure. In 0.2 mol·L^-1 HOAc-NaOAc buffer （pH=5.3） containing 2.2×10^-2 mol·L^-1 K2S2O8 and 0.002% Triton X-100, the 2.5th-order derivative stripping peak current of the catalytic wave at 0.3 V （vs. Ag/AgCl） is rectilinear to amiodarone concentration in the range of 2.0×10^-10-2.3×10^-8 mol·L^-1 with a detection limit of 1.5×10^-10 mol·L^-1 after accumulation at 0 V for 30 s.     

碳糊电极阳极吸附伏安法测定环丙沙星

报道了用碳糊电极阳极吸附伏安法测定环丙沙星的新方法.在 0. 40mol/L的NH4Ac HAc(pH4. 30)缓冲液中,使用JP 303极谱分析仪,环丙沙星在碳糊电极 (CPE)上有一灵敏的吸附伏安氧化峰,峰电位为1. 12V(vs.SCE).该氧化峰的二阶导数峰电流与环丙沙星的浓度在 8. 0×10-9 ~8. 0×10-7 mol/L(富集 90s)范围内成良好的线性关系,相关系数为 0. 998 8,检出限为 4. 0×10-9 mol/L(S/N=3,富集 110s).探讨了环丙沙星在碳糊电极上的伏安性质和电极反应机理,并且成功应用于人体尿样中环丙沙星含量的测定.加入回收实验,回收率在95. 5%至 103. 9%之间.