氟苯尼考的极谱法研究

应用循环伏安法、线性扫描伏安法和控制电位电解库仑法对氟苯尼考的电化学行为进行了研究。在0 .2mol/LNaOH NaH2 PO4(pH =7.6 )缓冲液中 ,对其进行扫描 ,发现于 - 0 .886V (vs.SCE)处产生一灵敏的还原峰 ,其峰电流与氟苯尼考的浓度在 1.0× 10 -5～ 7.0× 10 -4mol/L范围内呈良好的线性关系 (r =0 .9994 ) ;检出限为 1.0× 10 -6mol/L。对 1.0× 10 -4mol/L氟苯尼考溶液进行 10次平行实验 ,RSD为 0 .3%。实验结果表明 :氟苯尼考在极谱电极上有吸附性质 ;求得了电极反应的电子转移数为 2 ;研究了电极反应机理     

硒代胱氨酸在银电极上的电化学行为及其定量分析

研究了硒代胱氨酸 (SeCys)于0.03mol/L的硼砂 -NaOH( pH9.5)介质中在银电极上的电化学行为 ;实验发现在 -0.62V和 -0.68V(vsSCE)处存在一对氧化还原峰 ,其峰电流与硒代胱氨酸浓度具有良好的线性关系 ,由此建立了SeCys的电分析化学测定方法, (1)循环伏安法 ,其线性范围为8.6×10 -9～1.1×10 -7mol/L,检出限为4.3×10 -10mol/L, (2)二次微分线性扫描伏安法 ,其线性范围为2.2×10 -10～1.0×10 -8mol/L,检出限为8.6×10-11mol/L;该法应用于中药黄芪中SeCys含量的测定 ,结果令人满意 ;该文还探讨了硒代胱氨酸在上述条件下的电极反应机理     

呋喃丹的极谱法测定研究及应用

用循环伏安法(CV)、线性扫描伏安法(LSV)对呋喃丹的极谱伏安行为及其测定进行了研究。在0.2mol/L NH3-NH4Cl底液中(pH 8.8),对其进行扫描,发现于-1.21V(vs.SCE)处产生一灵敏的还原峰,其峰电流与呋喃丹的浓度在5.0×10-6-1.0×10-mol/L范围内呈良好的线性关系(r=0.9995)。对5.0×10-5mol/L呋喃丹溶液进行6次平行实验,RSD为0.2％。实验结果表明,呋喃丹在极谱电极上有吸附性质。同时对电极反应机理进行了研究。该方法对微生物降解呋喃丹进行监测取得满意的结果,96 h内呋喃丹的降解率为98％。     

舒乐安定在铂离子注入修饰电极上的电化学行为及其应用

舒乐安定在0.1 mol/L NH3-NH4Cl缓冲溶液(pH 9.40)中,用线性扫描伏安法,在Pt/GC离子注入修饰电极上,形成一良好的线性扫描伏安还原峰,峰电位Ep=-0.70V(vs.SCE)。其峰电流与舒乐安定浓度在3.0×10-9-1×107和1×10-7-1.5×10-6mol/L范围内呈线性关系,相关系数均为0.9999,检出限为3.0×10-9mol/L。并用于片剂的测定,回收率在96.5％～98.5％之间,结果是可靠的。用循环伏安法研究了体系的性质。实验表明,电极过程为不可逆吸附。用AES、XPS和SEM等表面分析方法证明,Pt离子确实注入到玻碳基体电极表面,Pt以原子态存在,催化了舒乐安定的还原。     

灰黄霉素的伏安行为及其测定的研究

灰黄霉素在0.1mol LHAc NaAc底液(pH5.0)中,产生灵敏的线性扫描极谱导数峰,峰电位为-1.28V(vs.SCE),峰电流与灰黄霉素浓度在2.0×10-7～2.0×10-6mol L范围内成线性关系。用于灰黄霉素片剂的测定。用线性扫描和循环伏安法等手段研究体系的伏安行为,结果表明,该体系属具有吸附性的不可逆过程。     

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。     

极谱催化波测定脉络宁口服液中的肉桂酸

应用线性扫描极谱法(LSV)、循环伏安法(CV),在1.0 mol/L HAc-NaAc(pH 4.1)含溶解氧的支持电解质中,对肉桂酸的电化学行为进行了研究。在该支持电解质中于-1.50 V(vs.SCE)处发现肉桂酸产生一灵敏的催化极谱还原峰,其峰电流与肉桂酸的浓度在2.5×10-6~7.5×10-4mol/L范围内呈良好的线性关系(r=0.999 1);检出限为8.0×10-7mol/L,对8.0×10-5mol/L的肉桂酸溶液进行11次平行测定,RSD为1.4%。并采用循环伏安法对肉桂酸的电极反应机理进行了探讨,结果表明该电极反应过程为不可逆过程。该方法已用于测定脉络宁口服液中的肉桂酸。     

单扫描示波极谱法同时检测哌拉西林钠和氯霉素

建立了一种同时测定哌拉西林钠和氯霉素的单扫描示波极谱法。在0.66 mol/L KCl(pH 7.20)底液中,氯霉素和哌拉西林钠在汞电极上均有一灵敏的导数还原峰,哌拉西林钠和氯霉素的峰电位分别为-1.230 V和-0.638 V,检出限分别为4.5×10-8和8.2×10-9mol/L,峰电流与浓度分别在9.0×10-6~7.0×10-8mol/L和4.0×10-6~4.0×10-8mol/L范围有良好线性关系,r均大于0.998。将该法应用于氯霉素滴眼液和注射用的哌拉西林钠中氯霉素及哌拉西林钠的测定。用单扫描示波极谱法和循环伏安法研究了哌拉西林钠和氯霉素的电化学行为,实验表明该体系为一具有吸附性的不可逆过程。     

核黄素的微分脉冲溶出伏安分析

采用循环伏安法和微分脉冲溶出伏安法,对核黄素在裸金电极和巯基化合物分子自组装膜修饰金电极上的电化学行为进行了研究,发现在pH4.8的B-R缓冲溶液中,核黄素在裸金电极和分子自组装膜修饰金电极上均于-0.35V左右产生一对可逆的氧化还原峰。核黄素在裸金电极和谷胱甘肽、三巯基丙酸、二巯基苯丙咪唑分子自组装膜修饰金电极上,其浓度分别在3.0×10-7～2.3×10-4mol/L、1.05×10-6～2.0×10-4mol/L、2.1×10-6～2.08×10-4mol/L、1.05×10-6～2.0×10-4mol/L范围内与微分脉冲伏安峰峰电流之间有良好的线性关系,其相关系数分别为0.9932、0.9909、0.9857、0.9832,核黄素的检出限为2.1×10-7mol/L、5.2×10-7mol/L、8.6×10-7mol/L、5.2×10-7mol/L。对浓度为1.0×10-5mol/L的核黄素进行10次平行测定,所得峰电流的相对标准偏差为2.0%。将该方法用于核黄素片剂和复合维生素B片剂的测定,结果令人满意。     

西维来司他的极谱伏安法研究

应用循环伏安法(CV)、线性扫描伏安法(LSV)、控制电位电解库仑法(BE)对西维来司他的电化学行为进行了研究。在0.2mol/LHAc-NaAc(pH=5.6)缓冲液中,对其进行扫描,发现于-1.29V(vs.SCE)处产生一灵敏的还原峰,其峰电流与西维来司他的浓度在1×10-5~2×10-4mol/L范围内呈良好的线性关系(r=0.9976);检出限为2.0×10-6mol/L。对5.0×10-5mol/L西维来司他溶液进行12次平行实验,RSD为0·56%。实验结果表明,西维来司他在极谱电极上有吸附性质,并为此求得了电极反应的电子转移数为4,同时对电极反应机理进行了研究。     

阳极溶出催化伏安法的理论研究 Ⅱ.不可逆电极溶出

本文对在玻璃碳电极上不可逆溶出催化的理论进行了研究,推导了溶出催化过程的电流方程,峰电流和峰电势方程,并用微计算机模拟出各种关系曲线,从理论方程得知溶出催化伏安法所得的峰电流比溶出伏安法的峰电流提高了二个数量级。本文还用钯的溶出催化实验验证理论方程,所得的实验结果均与理论方程相吻合。     

阳极溶出催化伏安法的理论研究 Ⅰ.可逆电极溶出

本文推导了玻璃碳电极上可逆溶出催化过程的理论电流方程、峰电流及峰电势方程,得知溶出催化伏安法所得的峰电流比溶出伏安法的峰电流提高了数十倍,从而进一步提高了溶出伏安法的灵敏度。本文还用碲的溶出催化实验验证理论方程。所得实验结果均与理论方程相吻合。     

A complete numerical simulation of the techniques of alternating current linear sweep and cyclic voltammetry: analysis of a reversible process by conventional and fast Fourier transform methods

We describe the method of achieving the first completely general simulation of ac linear sweep and cyclic voltammetry making use of the fully implicit Richtmyer modification (FIRM) method. The simulation technique is applied to a reversible process under conditions where a sinusoidal waveform of any amplitude is superimposed onto the dc potential which is swept at a finite scan rate. Results, where possible, are compared with the existing theory derived at constant dc potential to confirm the fidelity of the simulation. In particular, we demonstrate excellent agreement with the results of Engblom et al. [J. Electroanal. Chem. xxx (1999) xxx] for large amplitude ac voltammetry described in the companion paper immediately preceding this article. The use of conventional and Fourier transform methods of data analysis are compared to highlight the advantages of the use of the fast Fourier transform algorithm in ac voltammetry.     

对位叠式循环方波伏安法：Ⅱ.平行催化体系

本文提出平行催化体系的对位叠式循环方波伏安法，并对共作了系统的研究，推导了这一方法的催化电流理论方程，并用验验证这理论的正确性，得到其各脉冲电流皆为同方向，对位叠式循环催化电流相当于将电流叠加４次，而波形不受方波幅度大小的影响，因而灵敏度和分辨率有较大提高，优于其它方波伏安法。     

Electroanalytical Determination of Morpholine as a Corrosion Inhibitor at a Cathodically Pretreated Boron-Doped Diamond Electrode

An electroanalytical method for the determination of morpholine, a corrosion inhibitor, was developed at a cathodically pretreated boron-doped diamond electrode (BDDE). The voltammetric response of morpholine at the BDDE in 0.1?mol L^?1 KCl (pH 10) shows an irreversible oxidation process at approximately 1.3?V vs. Ag/AgCl in 3.0?mol L^?1 KCl. Using cyclic voltammetry, the number of electrons involved in the morpholine electroxidation mechanism was found to be 1. The application of chronoamperometry showed that the apparent diffusion coefficient (D₀) was 2.99?×?10^?6 cm² s^?1. Using square wave voltammetry under the optimized conditions (frequency of 30.0?Hz, pulse amplitude of 100?mV and step potential of 20?mV at pH 10.0), the developed method provided limits of detection and quantification of 2.1 and 6.9?mg L^?1, respectively, with a linear range from 5.0 to 100.0?mg L^?1 (r?=?0.991). Intraday (n?=?10) and interday (two consecutive day) precision values assessed as the relative standard deviation for solutions containing 30.0, 60.0, and 90.0?mg L^?1 of morpholine were from 0.41 to 5.86% and 0.92 to 3.19%, respectively. The feasibility of the method for the interference-free determination of morpholine was verified by the analysis of synthetic boiler water samples containing CaCO₃, Na₂SO₃, Na₃PO_4, FeCl₃, and humic acid as organic matter. In addition, hydrazine was added as a possible interfering compound because of its widespread use in corrosion inhibition. Recovery values from 90.9 to 109.4% were obtained in the synthetic boiler water, thereby attesting to the accuracy of the method.     

Iron(III)‐mediated Electrochemical Detection of Levofloxacin in Complex Biological Samples

We report the design of an electrochemical sensor capable of detecting levofloxacin (LEVX) in complex biological samples. This detection strategy is simple, fast, and does not require sample pretreatment or electrode modification. Unlike previously developed electrochemical LEVX sensors that require direct oxidation of LEVX, the sensing mechanism is based on the complexation reactions between LEVX and iron(III), resulting in a concentration‐dependent decrease in the iron(III) reduction peak current and a shift in the peak potential. These changes are presumably attributed to the decrease in the concentration of uncomplexed Fe(III) in the solution. The concentration‐dependent change in both the current and potential can be used for quantification of LEVX in various samples, including 50 % synthetic urine and 25 % synthetic human saliva. The limit of detection was estimated to be in the range of 1.5 to 2.3 μM, concentrations that are much lower than the concentration of LEVX found in urine and saliva samples of patients administered this drug for conditions such as urinary tract infection. With further optimization, this sensing strategy could find applications in clinical pharmacokinetic studies.     

线性扫描伏安法研究司帕沙星的电化学行为

采用线性扫描伏安法和循环伏安法研究司帕沙星的电化学行为。在0.05 mol·L~(-1)硫酸溶液中,司帕沙星于-1.29 V(vs.Ag/AgCl)处产生一灵敏的还原峰,司帕沙星的浓度在1.0×10~(-6)～1.5×10~(-4)mol·L~(-1)范围内与其峰电流呈线性关系,检出限(3S/N)为2.0×10~(-7)mol·L~(-1)。该法用于司帕沙星片剂的分析,回收率为96.2%～105.0%,相对标准偏差(n=6)为2.4%。试验证实:司帕沙星在电极上产生的峰为具有吸附性的完全不可逆的还原峰。     

Graphene oxide modified glassy carbon electrode for determination of linagliptin in dosage form,biological fluids,and rats' feces using square wave voltammetry

An applicable square wave anodic adsorptive stripping voltammetric (SWAdASV) technique was utilized for linagliptin determination. A glassy carbon electrode was modified with graphene oxide to increase the electrode reactivity. The method is cheap, accurate, precise, and selective, with a good linearity range and a low detection limit. The proposed method was the first one to determine linagliptin in the feces, which is the main route for excreting the drug from the body. The electrode was characterized using various techniques, including Scanning Electron Microscope (SEM), Fourier-transform infrared (FTIR), and X-ray powder diffraction (XRD), and the oxidation mechanism of the drug was examined. The proposed method has a linear range of 9.45–103.96 ng mL^?1. The detection limit was 4.0 ng mL^?1. The modified electrode was employed efficiently to determine the drug in tablet formulations, spiked human urine, plasma, and rats' feces with high recoveries. The proposed method's results were statistically compared with those of another previously published method.     

微电极研究(Ⅹ)——微盘电极上稳态过程导数伏安法

本文研究了微盘电极上单扫描、一次导教、二次导数及三次导数的稳态扩散电流方程,一次导数的电流峰与扫描速率v成正比,二次导数及三次导数的电流峰分别与v²、v³成正比,从而提高了响应灵敏度,通过它们的波形可以很方便地求得电极反应的标准电极电位,判断反应的可逆性,用碳纤维微盘电极进行了验证,结果与理论方程一致。     

The surface catalytic mechanism: a comparative study with square-wave and staircase cyclic voltammetry

A pseudo-first-order catalytic mechanism in which both reactant and product of a redox reaction are strongly immobilized on an electrode surface is theoretically analysed under conditions of square-wave (SWV) and staircase cyclic voltammetry (SCV). A mathematical procedure is developed under diffusionless conditions. The relationships between the properties of the voltammetric response and both the kinetic parameters of the redox reaction and the parameters of the excitation signal are studied. The phenomenon of the quasi-reversible maximum is discussed. A comparative study between SWV and SCV is presented and the limitations and advantages of both techniques, from analytical and kinetic points of view, are discussed. The theoretical predictions are experimentally confirmed by the redox reaction of azobenzene in the presence of hydrogen peroxide as an oxidizing agent. Electronic Publication