邻苯二酚紫修饰电极示差脉冲伏安法测定水中铝

利用吸附的方法在热解石墨电极上制得邻苯二酚紫(PCV)修饰电极。在NH~3.H~2O-NH~4Cl底液(pH8.5)中,该电极具有很好的电化学活性,其示差脉冲氧化峰电位为E~p~a=+80mV。对铝进行检测,只是峰电流降低,而峰电位不变,氧化峰电流的降低值与铝浓度在1×10^-^8-1×10^-^7mol.dm^-^3和1×10^-^7-1×10^-^6mol.dm^-^3范围内成正比,检测限为5×10^-^9mol.dm^-^3,标准偏差为5.0%(4×10^-^8mol.dm^-^3Al,n=8),对实际水样进行测定,结果令人满意。对其检测机理进行了研究后认为:(1)PCV修饰电极表面是PCV单分子层吸附,具有很好的电化学活性;(2)铝与PCV在电极表面形成一1:3的配合物,该配合物在修饰电极上本身没有电化学活性,仅覆盖住原有的PCV电活性点,从而使峰电流降低,而峰电位没有变化;因此,在有铝和无铝时,电极过程没有变化,都对应于PCV的电化学行为。我们用电化学方法、扫描电镜、X射线光电子能谱和X射线荧光光谱法对此进行了证明。     

氟哌啶的吸附溶出伏安法研究

在NH~3-NH~4Cl底液中, 氟哌啶(Dro)在汞电极上有一线性扫描还原峰。E~p~c=-1.46V(vs.饱和Ag/AgCl电极)。该峰具有明显的吸附性。当Dro浓度较小, 扫描速度较快, 搅拌富集时间较长时, 电极反应完全为吸附态的Dro的还原所控制。吸附粒子为Dro中性分子。测得Dro在汞电极上的饱和吸附量为1.12x10^-^1^0mol.cm^-^2, 每个Dro分子所占电极面积为1.48nm^2, 不可逆吸附的转移系数α为0.58。并建立了吸附溶出伏安法测定Dro的最佳条件, 最低检测限为1.0x10^-^9mol.dm^-^3。     

利凡诺的吸附溶出伏安法研究

在NH~3-NH~4Cl底液中,利凡诺(RIL)在汞电极上有一线性扫描还原峰,E~P~C=-1.42V(vs.饱和Ag/AgCl电极).该峰具有明显的吸附性.当RIL浓度较小,扫描速度较快,搅拌富集时间较长时,电极反应完全为吸附态的RIL的还原所控制.吸附粒子为RIL中的二氨基乙氧基丫啶中性分子.测得RIL在汞电极上的饱和吸附量为4.0×10^- ^1^0mol·cm^-^2,每个RIL分子所占电极面积为0.42nm^2,电子转移数n为2, 不可逆吸附的转移系数α为0.71.探讨了RIL在汞电极上还原的机理. 并建立了吸附溶出伏安法测定RIL的最佳条件,最低检测限为1.0×10^-^9mol·dm^-^3     

单分子聚苯胺膜电极上抗坏血酸的线性扫描催化氧化波研究

在苯胺浓度为1.0mol.dm^-^3的盐酸溶液中用电化学聚合法制得单分子聚苯胺膜电极。在该修饰电极上, 抗坏血酸在0.01mol.dm^-^3盐酸底液中有一线性扫描催化氧化波, 其峰电位为+0.270V(vs.SCE), 峰电流与抗坏血酸浓度在10^-^2～10^-^5mol.dm^-^3范围内呈线性关系。文中详细地探讨了该波的性质, 证实它是一个不可逆波, 并且测定了αAn, ks, DR值。     

肌红蛋白在磷脂-月桂酸修饰的玻碳电极上的电化学行为及其分析应用

报道了肌红蛋白(Mb)在磷脂、月桂酸修饰的玻碳电极上的电化学行为 ,在 +0.2～ -0.7V(vs.Ag/AgCl)电位范围内 ,于pH6.0的0.01mol·L-1的KH2PO4、Na2HPO4底液中 ,肌红蛋白产生不可逆的还原电流峰 ;还原峰电流与肌红蛋白浓度在2.25×10-8 ～1.40×10-6 mol·L-1 范围内呈良好线性关系 ;线性回归方程为Ip(μA)=-0.01419 +0.2382cMb(10 -7mol·L -1) ,线性回归系数r(10)为0.998 ,检出限为1.20×10 -8mol·L -1,该电极可作为检测肌红蛋白的新型的高灵敏度电化学生物传感器。     

聚吖啶橙修饰电极上多巴胺的电化学行为及其伏安法检测

在玻碳电极上用电化学方法制备了聚吖啶橙修饰膜电极并研究了此电极上多巴胺的电化学行为及其检测。多巴胺在聚吖啶橙修饰电极上于0.50V和0.47V处出现一对灵敏、可逆的氧化还原峰。在最佳测试条件下,氧化峰电流与多巴胺浓度在2.8×10-7～5.3×10-3mol·L-1范围内呈良好的线性关系。0V处闭路富集150s,检出限为7.0×10-9mol·L-1,用于多巴胺针剂含量的测定,结果满意。     

司帕沙星的吸附伏安特性及其应用

在0.2mol·L-1 KH2PO4-K2HPO4(pH6.80)底液中,司帕沙星(sparfloxacin,简称SPFX)在汞电极上有一线性扫描还原峰,峰电位Vp= -1.40V(vsAg/AgCl),该峰具有明显的吸附性 ;吸附粒子为SPFX中性分子,测得SPFX在汞电极上的饱和吸附量Гs =5.08×10-11 mol·cm-2,每个SPFX分子所占电极面积为3.27nm2,SPFX在汞电极上的吸附符合Langmuir吸附等温式 ;测得吸附系数 β=1.04×106,25℃时的吸附自由能ΔGФ= -34.33kJ·mol -1,电极反应电子数n=2,不可逆体系动力学参量αnα=1.54,表面电极反应速率常量ks=0.29s -1 ;建立了吸附溶出伏安法测定SPFX的最佳条件,方法的检出限为2.0×10 -8mol·L -1。     

聚L-苏氨酸修饰电极对多巴胺和肾上腺素的电催化氧化

利用循环伏安法将L-苏氨酸聚合修饰在玻碳电极表面, 制成聚L-苏氨酸修饰电极. 实验表明, 该电极对多巴胺和肾上腺素都有较好的催化氧化效果. 运用循环伏安法详细研究了修饰电极的电化学性质. 在pH 2.5的磷酸盐缓冲溶液(PBS)中, 肾上腺素的电子传递系数为0.51, 表观反应速率常数为1.33 s-1; 在pH 7.5的PBS中, 多巴胺在电极上产生一对氧化还原峰, 多巴胺在电极上的电子传递系数为0.60, 表观反应速率常数为0.92 s-1. 该修饰电极对多巴胺和肾上腺素能够进行同时测定, 还原峰电流与多巴胺和肾上腺素浓度分别在1.0×10-6-5.0×10-4 mol·L-1和3.0×10-6-1.0×10-4 mol·L-1范围内呈现良好的线性关系.     

电聚合卟啉衍生物修饰的碘离子选择性电极

用电化学方法将α,β,γ,δ-四(4-氨基苯基)卟啉单体聚合在铂丝电极上, 可制备化学修饰型I^-选择性电极.质子化卟啉衍生物的立体交联高聚大环与I^- 的作用具有强的主客体效应,使电极对I^-具有高的选择性,并呈现与经典Hofmeister 系列及一般金属卟啉中性载体膜电极不同的阴离子选择性次序:I^-》SCN^-》ClO~4^->NO~2^->Br^->NO~3^->Cl^->SO~4^2^-.电极对1×10^-^1～2.6×10^-^6mol ·dm^-^3呈线性响应,检测下限8.2×10^-^7mol·dm^-^3,斜率61±0.2mV/pI^-(27℃).测试了电极膜的交流阻抗行为.电极具有内阻小,响应快,抗毒化能力强,制备简单等优点     

聚苯胺黄嘌呤氧化酶电极的生物电化学活性

用电化学方法将黄嘌呤氧化酶固定在聚苯胺中以制成聚苯胺黄嘌呤氧化酶电极。该电极呈现典型的酶催化反应动力学特性。且具有快速的生物电化学响应。固定化黄嘌呤氧化酶的表观米氏常数为21×10^-^6mol.dm^-^3, 最适pH为8.4,酶催化反应的活化能为85.1kJ.mol^-^1。酶电极具有较高的稳定性。使用聚苯胺黄嘌呤氧化酶电极能可靠地测定较低的底物浓度, 如2×10^-^6mol.dm^-^3黄嘌呤。     

Polarographic study of acrolein and its determination by flow injection with amperometric detection at a mercury electrode

A study of the electrochemical behavior of acrolein at a dropping mercury electrode using different polarographic techniques is described. Theoretical studies of the reversibility of the wave of acrolein were carried out using two different polarographic techniques: direct current tast and differential pulse. Differential pulse polarography may be used to determine acrolein concentration in a Britton-Robinson buffer solution of pH 10 in the ranges 2 x 10(-7)10(-8) and 5 x 10(-8)-10(-4) mol dm(-3) and a coefficient of variation of 1.7% for a concentration of 10(-5)mol dm(-3). A flow injection method with amperometric detection at a potential of -1.4V using a mercury electrode is also described. Before each injection, any drop hanging from the tip of the capillary needs to be dislodged and a new electrode drop dispensed; three different drop sizes were tested. A linear relationship between peak intensity and acrolein concentration was obtained in the range 10(-5)-10(-7) mol dm(-3), with a detection limit of 9.8 x 10(-8) mol dm(-) 3 and a coefficient of variation of 2.9% for a 2 x 10(-7) mol dm(-3) concentration. Several organic and inorganic species were tested in order to ascertain whether they interfered with the signal for acrolein. The proposed methods were applied to the determination of acrolein in seawater samples.     

线性变位极谱法研究XX. 卷积和去卷积配位吸附不可逆波理论

本文提出线性变位极谱卷积和去卷积配位吸附不可逆波理论, 并进行了验证,实验结果与理论相符。     

Cathodic adsorptive stripping voltammetric determination of uranium with potassium hydrogen phthalate

The adsorption properties of dioxouranium (II)-Phathalate complexes onto hanging mercury drop electrode are exploited in developing a highly sensitive and selective stripping voltammetric procedure for the determination of uranium (VI). The reduction current of adsorbed complex ions of U(VI) was measured by both linear sweep (LSCSV) and differential pulse cathodic stripping voltammetry (DPCSV), preceded by a period of preconcentration onto the electrode surface. As low as 2x10(-9) mol dm(-3) (0.5 mug/l) and 2x10(-8) mol dm(-3) (4.8 mug/l) with accumulation time 240 and 120 s using DPCSV and LSCSV, respectively, have been determined successfully. The relative standard deviation of 2.2% at the 5 ppm level was obtained. The interferences of some metal ions and anions were studied. The application of this method was tested in the determination of uranium in superphosphate fertilizer.     

微环电极上常规脉冲伏安法可逆波理论及其验证

本文推导了微环电极上常规脉冲伏安法电流方程式,对伏安曲线的性质进行了探讨.利用K~4Fe(CN)~6·KCl体系及金和铂微环电极对理论进行了验证,理论与实验结果相符.     

Association interaction and voltammetric determination of 1-aminopyrene and 1-hydroxypyrene at cyclodextrin and DNA based electrochemical sensors

The aim of this work was voltammetric determination of 1-aminopyrene and 1-hydroxypyrene using carbon paste electrodes modified with cyclodextrin derivatives and double stranded deoxyribonucleic acid (dsDNA). The detection schemes based on a preconcentration and differential pulse voltammetric (DPV) determination at beta-cyclodextrin and gamma-cyclodextrin modified carbon paste electrode (beta-CD/CPE, gamma-CD/CPE), neutral beta-cyclodextrin polymer and carboxymethyl-beta-cyclodextrin polymer modified screen-printed electrode (beta-CDP/SPE, beta-CDPA/SPE) and dsDNA modified screen-printed electrode (DNA/SPE) are proposed for the trace determination of studied analytes within the concentration range from 2 x 10(-8) to 4 x 10(-7) mol dm(-3) and from 2 x 10(-7) to 4 x 10(-6) mol dm(-3) with the limits of quantification down to 10(-8) mol dm(-3). Depending on pH, 1-aminopyrene interacts with both surface attached CD and DNA by electrostatic bonds and supramolecular complexation while 1-hydroxypyrene associates with the CD hosts via complexation. The 1-aminopyrene interaction with dsDNA was confirmed by fluorimetric measurements in the solution phase using a competing DNA-TO-PRO-3 dye complex. In addition, the effect of temperature on this association was investigated using an electrically heated DNA-modified carbon paste electrode (DNA/CPE).     

Application of electrochemical impedance spectroscopy to the study of dioleoyl phosphatidylcholine monolayers on mercury

Electrochemical impedance spectroscopy has been applied to the analysis of the behavior of monolayers of dioleoyl phosphatidylcholine (DOPC) on a mercury electrode. Experiments were carried out in electrolytes KCl and NaCl (0.1 mol dm(-3)) and Mg(NO3)2 (0.05 mol dm(-3)), and the frequency dependence of the complex impedance was estimated between 65 000 and 0.1 Hz at potentials -0.4 to -1.5 V versus Ag/AgCl 3.5 mol dm(-3) KCl at uncoated and coated electrode surfaces. Experiments were also carried out in the presence of gramicidin A (gA). Between the potentials of -0.4 and -0.7 V, the DOPC monolayer behaves as an almost ideal capacitor with little frequency dispersion. At more negative potentials, the impedance data show the formation of defects (-0.7 to -0.85 V), ingression of electrolyte into the layer (capacitance peak approximately -0.935 V), reorientation of phospholipid-water structures (capacitance peak approximately -1.0 V), and initiation of phospholipid desorption (approximately -1.3 V). gA interaction with the phospholipid monolayer at -0.4 V is shown as an additional low-frequency element. A general "one capacitor model" in a RC series equivalent circuit is developed incorporating the frequency dispersion of the capacitance, distribution of the time constants of the dispersion, and a coefficient related to the interface between the solution and the coated electrode. This latter coefficient is the most robust and decreases at potentials approaching those coincident with the DOPC phase transitions.     

二(乙基黄原酸基)金属配合物为中性载体高选择性碘离子电极的研究

本文研究了二(乙基黄原酸基)金属配合物为中性载体的阴离子选择性电极,其中二(乙基黄原酸基)钴(Ⅱ)对碘离子有高的选择性, 且电极呈现反Hofmeister行为, 其选择次序是: I^->SCN^->NO2^->Br^->ClO4^->SO4^2^->NO3^->Cl^-, 采用交流阻抗和光谱分析技术研究了电极的响应机理, 并将电极用于药品分析,结果令人满意。     

长链四烷基锡作中性载体的亚硝酸根选择性电极的研究

用亲脂的长链四烷基锡作中性载体制备亚硝酸根选择性电极. 其选择性模式与经典的阴离子交换剂相比有显著不同, 相对硝酸根的电位选择性系数改善约4个数量级. 线性响应区间为1x10^-^1-2x10^-^5mol.dm^-^3, 检测下限为5x10^-^6mol.dm^-^3. 电极斜率在弱性介质中为Nernst响应, 在弱酸性介质中为两倍Nernst响应. 紫外光谱研究发现酸度影响载体与阴离子的多级配位平衡. 电极斜率的变化与此平衡密切相关, 在此基础上给出了对电极斜率的异常变化及电位-pH     

Potentiometric PVC membrane sensor for the determination of scopolamine in some pharmaceutical formulations.

A novel PVC membrane electrode for the determination of scopolamine ion based on the formation of an ion-association complex of scopolamine with the phosphotungstate counter anion as an electroactive material dispersed in a PVC matrix is described. The sensor shows a fast, stable, near-Nenstian response for 1 x 10(-2) mol dm(-3) to 1 x 10(-6) mol dm(-3) scopolamine at 25 degrees C over the pH range of 3 - 7 with a cationic slope of 54.5 +/- 0.5 mV/decade. The lower detection limit is 8 x 10(-7) mol dm(-3) and the response time is 15 -45 s. The selectivity coefficients for scopolamine relative to the number of interfering substances were investigated. There was negligible interference from the studied cations, anions, and pharmaceutical excipients. The determination of scopolamine in aqueous solution shows an average recovery of 100.0% and a mean relative standard deviation (RSD) of 1.5% at 500 microg/cm3. The direct determination of scopolamine in some formulations (scopolamine injection and eye drops) gave results that compare favorably with those obtained by the United State of Pharmacopoeia method. Potentiometric titration of scopolamine with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the developed scopolamine electrode as an end point indicator electrode.     

Voltammetric determination of niclosamide at a glassy carbon electrode

A very sensitive and selective procedure was developed for the determination of niclosamide based on square-wave voltammetry at a glassy carbon electrode. Cyclic voltammetry was used to investigate the electrochemical reduction of niclosamide at a glassy carbon electrode. Niclosamide was first irreversibly reduced from NO2 to NHOH at -0.659 V in aqueous buffer solution of pH 8.5. Reversible and well defined peaks at -0.164 V and -0.195 V (vs. Ag/AgCl) were obtained that are responsible for two electron peaks between NHOH and NO. Following optimisation of the voltammetric parameters, pH and reproducibility, a linear calibration curve over the range 5 x 10(-8)-1 x 10(-6) mol dm(-3) was achieved. The detection limit was found to be 2.05 x 10(-8) mol dm(-3) niclosamide. For eight successive determinations of 5 x 10(-7) mol dm(-3) niclosamide, a relative standard deviation of 2.4% was obtained. This voltammetric method was applied to the direct determination of niclosamide in tablets. The results of the analysis suggest that the proposed method has promise for the routine determination of niclosamide in the products examined.