马兜铃酸极谱研究

用单扫示波极谱法研究马兜的电化学行为。在０．１ｍｏｌ／ＬＮａＯＨ底液中，马兜铃酸在－０．８９Ｖ产生一良好的二阶导数 极谱峰，线性范围为０．０３－３２ｍｇ／Ｌ检出限为０．０１ｍｇ／Ｌ。     

马兜铃酸的极谱研究

用单扫示波极谱法研究马兜铃酸的电化学行为．在０．１ｍｏｌ／ＬＮａＯＨ底液中，马兜铃酸在－０．８９Ｖ（ｖｓ．ＳＣＥ）产生一良好的二阶导数极谱峰，线性范围为０．０３～３２ｍｇ／Ｌ，检出限为０．０１ｍｇ／Ｌ．用该法测定中药关木通中马兜铃酸含量，结果满意．另外，还研究了马兜铃酸对由邻苯三酚自氧化产生的超氧自由基（Ｏ－·２）的清除作用．     

磺胺二甲嘧啶的极谱伏安行为

本文考察了磺胺二甲嘧啶在多种底液中的极谱伏安行为，发现其在ＢｒｉｔｏｎＲｏｂｉｎｓｏｎ（ＢＲ）缓冲溶液（ｐＨ２．２）中产生一个良好的还原峰，峰电位为－０．８５Ｖ（ｖｓ．ＳＣＥ），峰电流与磺胺二甲嘧啶浓度在１×１０－７３×１０－４ｍｏｌ／Ｌ范围内呈良好的线性关系，检出限为９×１０－８ｍｏｌ／Ｌ，大多数金属离子和无机阴离子不干扰测定，可望用于定量测定用多种电化学方法研究了该还原峰电流的性质，结果表明，它是具有吸附性质的不可逆还原峰     

头孢噻肟钠的极谱伏安行为及其单扫描示波极谱法测定

以多种电化学手段研究了头孢噻肟钠的极谱伏安行为，在磷酸盐缓冲溶液中，头孢噻肟钠产生了一个不可逆吸附不原波，其峰电位为－０．７７Ｖ（ｖｓ．ＳＣＥ）。有二个电子和一个质子参与了电极反应。电极反应速率常数Ｋｓ为９．０×１０＾－６ｃｍ．ｓ＾－１。     

博莱霉素A5的示波极谱行为及测定

在０．０５ｍｏｌ／Ｌ Ｈ２ＳＯ４支持电解质中，博莱霉素Ａ５出现二个示波极谱导数还原峰，峰电位Ｅｐ１＝－０．８２Ｖ和Ｅｐ２＝－１．０８Ｖ（ｖｓ．ＳＣＥ）。峰电流ｉｐ１比峰电流ｉｐ２小得多。ｉｐ２与博莱霉素Ａ５的浓度在５．０＊１０＾－８－４．０＊１０＾－６ｍｏｌ／Ｌ范围内呈线性关系；检出限为１．０＊１０＾－８用于老鼠血样中博莱霉素Ａ５含量的测定，得到满意的结果，对第二个峰的电化学行为作了初步探讨。     

肾上腺素的示波极谱行为及测定

以0.1 tool·L-1磷酸二氢钾-磷酸氢二钾缓冲溶液作底液,肾上腺素在示波计时电位图阴极支-0.45 V(vs.SCE)处生产生1个灵敏的切口,该切口深度随肾上腺素浓度增大而加深,基于此建立了测定针剂中肾上腺素的示波计时电位方法.试验结果表明:测定肾上腺素线性范围为2·0X10-5～2.0X10-4mol·L-1,线性回归方程为h=0.641 2.84X 103c(式中h为切口深度,单位V,C为肾上腺素浓度,单位mol·L-1),相关系数为0.996 1,检出限为6X 10-6mol.L-1;应用此方法测定了针剂试样中肾上腺素的含量,所得结果与标示值相符,其相对标准偏差(n=8)为2.5%,加入标准溶液作回收试验,测得回收率结果在98.0%～101.6%之间.     

示波极谱法测定聚碳酸酯塑料中双酚A

建立了聚碳酸酯塑料中双酚A的示波极谱测定法。聚碳酸酯塑料用蒸馏水浸泡 48h后 ,用二氯甲烷萃取 ,挥干二氯甲烷。样品中的双酚A在 80℃水浴中与硝酸反应生成硝基化合物。该化合物可在示波极谱仪上产生一灵敏的二阶导数吸附波。在 5～ 1 5 0 μg·L-1范围内峰电流与双酚A的含量呈良好线性关系。方法检出限为 2 μg·L-1,相对标准偏差为 0 .9%～ 8.5 % ,试验表明 ,方法所得结果与HPLC法所得结果间无显著差异     

邻苯二胺的示波极谱研究

邻苯二胺在含有Ｃｕ＾２＾＋及ＣＴＭＡＢ的ＮＨ４Ｃｌ－ＮＨ３．Ｈ２Ｏ缓冲溶液中，能被Ｃｕ＾２＾＋催化氧化，氧化产物在单扫描示波谱仪上产生灵敏的附还原波，峰电位为－０．４７Ｖ，邻苯二胺浓度在１０－２００ｎｍ／ｍＬ范围与峰电流呈良好的线性关系。本还探讨了邻苯了邻苯二胺氧化产物在滴汞电极表在贩吸附行为及其反应过程的机理。     

硫代硫酸根的溶出伏安吸附性质及应用

在 0 .0 1mol·L-1LiNO3介质中 (pH 2 .70 )S2 O32 -有一灵敏的阴极溶出峰( - 0 .42V) ,其峰电流与S2 O32 -浓度在 1× 1 0 -7mol·L-1～ 4× 1 0 -6mol·L-1范围内有线性关系。当富集 2 0 0s时 ,检测限可达 5× 1 0 -8mol·L-1。溶出峰具有吸附性质 ,在悬汞电极上的吸附符合Frumkin等温式。测得在悬汞电极上的饱和吸附量为 1 .0 3× 1 0 -9mol·cm-2 。该方法用于PbS2 O3溶度积的测定 ,结果与文献值基本一致。     

Characteristics of the voltammetric behavior of the hydroxide ion oxidation at disordered mesoporous titanium dioxide electrocatalyst

The alkaline water electrochemical splitting reactions need economical, very energetic, and durable catalysts. Here, a disordered mesoporous and highly defected titanium dioxide (dom-TiO₂) electrocatalyst for the oxidation of hydroxide ion was prepared via ligand-assisted evaporation-induced self-assembly. The (dom-TiO₂) electrocatalyst showed significant electrocatalytic performance for the oxidation of hydroxide ion compared to that of non-porous TiO₂ (bare-TiO₂) and highly-ordered hexagonal mesoporous (hm-TiO₂) electrodes. The chemical and electrochemical parameters of the diffusion (D), concentration in the bulk (C_b), the number of transferred electrons (n), rate constant of heterogeneous electron transfer (k_s), redox potential (E°), and homogeneous chemical rate constant (k_c) for the oxidation of hydroxide ion reaction at the porous TiO₂ electrodes were determined via the convolution–deconvolution voltammetry and competed against that of non-porous (bare-TiO₂) and hm-TiO₂ and catalysts. In addition to the effect of dom-TiO₂ film thickness and the type of supporting electrolytes on the electrochemical parameters of the electrocatalytic oxidation of OH^– ions have been estimated. The convolutive–deconvoluted results show that the dom-TiO₂ electrode catalyst exhibits a superior reaction rate constant among the studied electrodes that depend on the film thickness and type of supporting electrolyte.     

盐酸克伦特罗在玻碳电极上的伏安行为研究

采用电化学技术研究了盐酸克伦特罗(CLB)在玻碳电极上的电化学还原行为。在pH4.54的Britton Robinson缓冲液中,CLB于 0.38V(vs.Ag AgCl)左右处出现一个明显的方波溶出伏安还原峰,峰电流与CLB的浓度在3.0×10-7～1.0×10-5mol L范围内呈良好的线性关系,检出限为5.1×10-8mol L。该法可应用于模拟兔血清及尿样中CLB的测定。     

Polarographic and voltammetric behaviour of 2-hydroxy-3-tert-butyl-5-methylazobenzene

The polarographic and voltammetric behaviour of 2-hydroxy-3-tert-butyl-5-methylazobenzene has been studied in aqueous-ethanol mixtures of different pH using DCP and DPP polarographic and CV and SWV voltammetric methods. The reduction of the azo linkage takes place via two electrons at pH > 7, but four electrons at pH < 7 in aqueous-ethanol mixtures. It has been determined that there is a linear relationship between the current and concentration and the lowest detection limit has been found as 1 × 10^–7 M (for SWV).     

加雷沙星的吸附伏安法测定

在0.3mol·L-1KH2PO4-Na2HPO4(pH6.40)底液中,加雷沙星(Garenoxacin,简称GRX)在汞电极上有一线性扫描还原峰,峰电位EP=-1.12V(vsAg/AgCl),该峰具有明显的吸附性;吸附粒子为GRX中性分子,测得GRX在汞电极上的饱和吸附量Гs=3.92×10-11 mol·cm-2,每个GRX分子所占电极面积为1.94nm2,GRX在汞电极上的吸附符合Langmuir吸附等温式;测得吸附系数β=1.14×106,25℃时的吸附自由能ΔGθ=-29.62kJ·mol-1,电极反应电子数n=2,不可逆体系动力学参量αna=1.04,表面电极反应速率常量ks=0.25s-1;建立了吸附溶出伏安法测定GRX的最佳条件,方法的检出限为2.0×10-8 mol·L-1.     

Adsorptive stripping square-wave voltammetric behavior of rofecoxib

Adsorption and reduction of rofecoxib were investigated by cyclic and square-wave voltammetry on a hanging mercury drop electrode in electrolytes of various pH values. The reduction process on hanging mercury drop electrodes gave rise to a single peak within the entire pH range (2.0-11.5). In alkaline solutions, rofecoxib gave a sensitive adsorptive reductive peak; approximately 10 times larger than those obtained by applying a square-wave scan without prior accumulation. Application of the method to the determination of rofecoxib in two pharmaceutical products (Vioxx 12.5 and 25 mg), without sample pretreatment, resulted in acceptable deviation from the stated concentrations.     

Electrochemical behavior of atomoxetine and its voltammetric determination in capsules

In this work, the electrochemical behavior and the analytical application of atomoxetine, a selective noradrenaline reuptake inhibitor, are studied. Atomoxetine, studied by differential pulse voltammetry and cyclic voltammetry on a glassy carbon electrode, exhibited an anodic response in aqueous media with pH between 1.5 and 7. In non-aqueous medium (acetonitrile), the drug exhibited two irreversible oxidation peaks that are diffusion controlled. From chronocoulometric studies in acetonitrile, it was determined that each oxidation signal involves two and four electrons, respectively. For analytical purposes, a differential pulse voltammetry technique in 0.1 mol L⁻¹ perchloric acid was selected, which exhibited adequate figures of merit. The percent recovery was 96.6 ± 1.2 and the detection and quantitation limits were 6.9 × 10⁻⁵ and 1.0 × 10⁻⁴ mol L⁻¹, respectively. Also, results indicate that excipients do not interfere with the oxidation signal of atomoxetine, which leads to the conclusion that the developed method is satisfactorily selective for atomoxetine quantification in pharmaceuticals with no prior separation or extraction necessary. Finally, the proposed voltammetric method was successfully applied to both the assay and the uniformity content of atomoxetine in capsules. For comparison, high-performance liquid chromatography analysis was also performed.     

Study on the electrochemical behavior and differential pulse voltammetric determination of rhein using a nanoparticle composite film-modified electrode

A sensitive electrochemical method was developed for the differential pulse voltammetric determination of rhein at a glassy carbon electrode (GCE) modified with a nanoparticle composite film. In the present paper, multi-wall carbon nanotube (MWNT) was dispersed into dihexadecyl phosphate (DHP) to give a homogeneous suspension. After the solvent evaporation, a uniform film of MWNT-DHP composite film was obtained on the GCE surface. The MWNT-DHP composite film-modified GCE exhibited excellent electrocatalytic behavior toward the redox of rhein. Compared with an irreversible reduction of rhein at the bare GCE, a reversible redox behavior of rhein was observed at the MWNT-DHP composite film-modified GCE and the redox current was also enhanced greatly. Based on this, a cathodic differential pulse voltammetry (DPV) was applied for the determination of rhein. The experimental parameters, which influence the current of rhein, were optimized. Under optimal conditions, the cathodic DPV measurements were performed and a linear response of rhein was obtained in the range from 1.0 x 10(-8) to 5.0 x 10(-6) mol L(-1) and with a limit of detect (LOD) of 5.0 x 10(-9) mol L(-1). The proposed procedure was successfully applied to assay rhein in real samples with satisfactory results.     

2-氨基酚在离子液体-壳聚糖复合修饰电极上的电化学行为及其测定

本文采用离子液体1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)和壳聚糖(Chi)作为修饰剂,制备了新型修饰电极BMIMPF6-Chi/GCE,采用该修饰电极研究了2-氨基酚(OAP)的电化学行为,并对其进行了分析检测。实验结果表明,在pH=6.5的PBS缓冲液中,OAP于0.197V处出现一个明显的氧化峰,逆向扫描无还原峰,说明OAP在该电极上的电化学行为是不可逆的。OAP氧化峰电流与扫速的1/2次方在40～280 mV.s-1的范围内呈良好的线性关系,表明该电极过程受扩散控制。在最佳实验条件下,OAP峰电流与其浓度在4.0×10-7～2.0×10-4mol.L-1范围内呈良好的线性关系,Ipa(μA)=-0.534-18.424c(10-4mol.L-1),R=0.999,检出限1.4×10-7mol.L-1(S/N=3),回收率为96.8～103.7%。     

葛根素的循环伏安测定及其电化学行为研究

在0.02 mol/L NH4Cl-NH3.H2O(pH8.0)的底液中,采用循环伏安法测定葛根素,得到一良好的氧化峰,峰电位Ep=+0.57V,峰电流Ip与葛根素的浓度在1.046×10-7～5.767×10-5mol/L范围内成线性关系,相关系数r为0.9989,检出限为1.046×10-7mol/L.测定葛根中葛根素的含量,平均回收率在99.8%.并且研究了葛根素在玻碳电极上的电化学行为,结果表明葛根素的电极过程具有吸附性和不可逆性.