Zr(Ⅳ)-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(Ⅱ)-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6.0×10-9～2.0×10-6 mol/L呈线性而测定Zr;检出限为3.0×10-9 mol/L(S/N=3).最佳测定条件为2.0 mol/L HCl、1.0×10-5 mol/L桑色素;富集电位为0V(vs.SCE);扫描速度为250 mV/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.     

碳糊电极阴极吸附伏安法测定橙皮甙

在0.4mol/L的NH4Cl-NH3(pH9.0)缓冲液中,使用JP-303极谱分析仪,橙皮甙在碳糊电极(CPE)上有一灵敏的吸附伏安还原峰,峰电位为-1.2V(vs.SCE).该还原峰的二阶导数峰电流与橙皮甙的浓度在2.0×10-8～1.0×10-6mol/L(富集90s)范围内成良好的线性关系,相关系数为0.9963,检出限为1.0×10-8mol/L(S/N=3,富集110s).探讨了橙皮甙在碳糊电极上的伏安性质和电极反应机理,并且成功应用于中草药桔皮中橙皮甙含量的测定.     

锆(Ⅳ)-邻苯二酚紫络合物碳糊电极阳极吸附伏安法研究

研究了锆(Ⅳ)-邻苯二酚紫(PV)络合物在碳糊电极上的吸附伏安行为。测定锆最佳条件为:0.08mol/L的HNO3为底液,于0.4V富集50s,从0.4至1.4V以100mV/s的速率线性扫描。在0.85V(vs.SCE)的二次导数氧化峰电流与锆的浓度在3.0×10-9～5.0×10-8mol/L(5.6×10-7mol/LPV)和1.0×10-8～1.0×10-7mol/L(5.6×10-6mol/LPV)成线性关系。富集80s,检出限为1.0×10-9mol/L(S/N=3)。该法用于标准岩石样品中锆的测定,不需萃取分离和掩蔽,直接测定,结果满意。铪(Ⅳ)在同样的实验条件下也于0.85V产生一络合吸附峰,灵敏度稍低于锆。     

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。     

镓(Ⅲ)-茜素氨羧络合剂在碳糊电极上的阳极吸附伏安法研究及应用

研究了镓(Ⅲ)-茜素氨羧络合剂(ALC)在碳糊电极上的阳极吸附伏安行为,并以此建立了一种高灵敏度、高选择性测定镓的吸附伏安法.在0.12 mol/L HAc-NaAc-0.24 mol/L邻苯二甲酸氢钾底液(pH 4.5)中,-0.10 V (vs.SCE) 富集90 s (或180 s),以250 mV/s扫速线性扫描至0.90 V, Ga3+-ALC在碳糊电极上产生灵敏的与ALC的峰电位相差近230 mV的吸附氧化峰,其二次导数峰电流与镓浓度在5.0×10-10～8.0×10-7 mol/L范围内呈线性关系;富集240 s检出限达3.0×10-10 mol/L(S/N=3).探讨了电极反应机理.该法用于粮食样品中镓的测定,结果满意.     

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     

碳糊电极上吸附伏安法测定痕量钪的研究

研究了钪(Ⅲ) 茜素氨羧络合剂(ALC)络合物在碳糊电极正电位区的吸附伏安行为,利用该络合物产生的二次导数吸附氧化峰电流与钪浓度成正比测定钪。其线性范围为2.0×10-9～6.0×10-7mol/L;富集120s,检出限达1.0×10-9mol/L(S/N=3)。探讨了电极反应机理。在同一支电极同一表面上15次连续测定4.0×10-8mol/L的Sc(Ⅲ),方法的相对标准偏差为3.7%。该法用于矿石样品中钪的测定,结果满意。     

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。     

钒-茜素S络合物在碳糊电极上的吸附伏安法研究

研究了钒-茜素S络合物在碳糊电极上的吸附伏安行为.在pH 5.1的NH4OAc-HOAc缓冲溶液中,钒-茜素S络合物在-0.52V(vs.SCE)产生一灵敏的吸附还原峰,峰高与钒的浓度在2.0×10-9～1.0×10-7mol@L-1范围内呈线性关系,检出限为8.0×10-10mol@L-1(富集240s).讨论了电极反应机理,方法已用于水样中痕量钒的测定,结果满意.     

锆-茜素红络合物在多壁碳纳米管修饰碳糊电极上的阳极吸附伏安法研究

制备了多壁碳纳米管修饰碳糊电极并研究了锆-茜素红络合物在该电极上的阳极吸附伏安行为,采用二阶导数线性扫描伏安法进行分析,实验结果表明,在0.128 mol/L氨基乙酸-0.048 mol/L邻苯二甲酸氢钾缓冲液(pH 4.0)中,在200 mV富集60 s,在200~1200 mV范围内以200 mV/s的速率线性扫描,络合物吸附在该修饰电极表面,于832 mV(vs.SCE)处产生一个灵敏的氧化峰,为络合物中配体茜素红的氧化所产生。络合物的峰电流与锆的浓度在1.0×10-11~2.0×10-7mol/L范围内呈良好的线性关系;检出限(S/N=3)为6.0×10-12mol/L(富集时间180 s)。方法用于岩矿样品中痕量锆的测定,结果满意。     

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%。