抗癌药长春新碱及其与微管蛋白相互作用的电化学研究

在 0 0 5mol/LTris,0 15mol/LNaCl溶液中 ,用吸附伏安法研究长春新碱 (VCR) ,其峰电位在 -1 68V (vs .Ag/AgCl) ,峰电流与 1 0× 10 -8～ 2 0× 10 -7mol/LVCR浓度成正比 ,检测限为 7 0× 10 -9mol/L .用常规脉冲极谱法、线性扫描和循环伏安法等研究该体系的电化学行为 .实验表明 ,电极还原过程为具有吸附特征的不可逆过程 .VCR的吸附符合Frumkin吸附等温式 .也研究了VCR与微管蛋白的相互作用 .实验表明 ,VCR与微管蛋白形成一电活性的结合物 ,这一结合物具有吸附性 ,且还原过程也为不可逆过程     

茜素修饰碳糊电极吸附伏安法测定痕量铜

报道了采用茜素修饰碳糊电极测定痕量铜的阳极溶出伏安法。在浓度为0 .1 mol/L 的 HAc- Na Ac缓冲溶液 (p H4.5)中 ,于 +0 .1 0 V处富集 ,- 0 .30 V还原后再进行阳极化扫描 ,于 - 0 .0 5V处获得一灵敏的铜的溶出峰 ,二次导数峰电流与铜浓度在 1 .6× 1 0 -9mol/L～ 4.7× 1 0 -7mol/L范围内呈线性关系 ,检出限达 8.0× 1 0 -10 mol/L。同时 ,对电极反应机理进行了讨论。方法应用于锌合金中铜的测定。     

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     

单扫示波极谱法测定氧氟沙星

在 0 .1 5mol/L HAc- Na Ac( p H 3.64)中 ,采用单扫示波极谱法测定氧氟沙星 ,得到一良好的还原峰 ,峰电位 Ep=- 1 .45V( vs.SCE)。峰电流 IP与氧氟沙星的浓度在 3.0× 1 0 - 7～ 6.2× 1 0 - 6 mol/L范围内呈线性关系 ,相关系数 r=0 .9983,检出限为 7.0× 1 0 - 8mol/L。此法已用于片剂的测定。用线性扫描和循环伏安法研究了体系性质 ,结果表明 ,氧氟沙星的电极过程为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。     

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。     

聚吖啶橙修饰电极伏安法测定黄嘌呤

报道了聚吖啶橙 (POAO)修饰电极多阶半微分伏安法测定黄嘌呤 (Xa)。在pH 5 .3的磷酸盐缓冲溶液中 ,Xa在POAO电极上于 0 .8V处产生一灵敏的氧化峰 ,峰电流与其浓度在 7.8× 1 0 - 8～ 1 .1× 1 0 - 6mol/L和 1 .1× 1 0 - 6～ 1 .0×1 0 - 5mol/L范围内呈良好的线性关系 ,检出限为 7.8× 1 0 - 9mol/L。方法可用于人尿中Xa的测定     

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.     

二次微分简易示波伏安法用于葛根素测定

根据在 0 .1 mol/ L Na OH溶液中 ,葛根素在二次微分简易示波伏安图阴极支-0 .95V ( vs.SCE)产生一灵敏峰的示波特性 ,建立了二次微分简易示波伏安法测定药品中葛根素含量的新方法。线性范围为 2 .5× 1 0 - 6～ 3 .5× 1 0 - 5mol/ L,相关系数为 0 .9985,检出限为 1× 1 0 - 6mol/ L,对 9.0× 1 0 - 6mol/ L葛根素进行 5次测定的RSD为 1 .5%。利用该法测定中药葛根及心可舒片剂中葛根素的回收率分别为 1 0 0 .2 %和 96.9%。     

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 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。     

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。     

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.     

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.     

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。     

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。     

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。     

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.     

微分脉冲阴极吸附溶出伏安法测定利多卡因

用微分脉冲阴极吸附溶出伏安法测定了利多卡因针剂的含量。浓度与波高的线性范围为1×10~(-7)～3×10~(-4)mol/dm~3。最低检测限l×10~(-8)mol/dm~3。回收率98.07±0.05%。