钒-5-溴水杨基荧光酮-氯酸盐体系极谱催化波的研究

在pH4.1的乙酸盐缓冲底液中,钒能与5-溴水杨基荧光酮形成络合物,并吸附在汞电极上,在氯酸盐存在下,在V(Ⅴ)的电极还原过程中形成催化波。用单扫二阶导数极谱法测定时,钒浓度在L.0×10-8～1.0×10-6mol·L-1范围内与峰高成正比关系,检出限为5.0×10-9mol·L-1。测得电活性络合物的组成为V(Ⅴ)5-Br-SAF＝11。平行催化反应的速率常数k=1.9×103(mol·L-1)-1·s-1。     

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。     

桑色素修饰碳糊电极吸附溶出伏安法测定人尿中痕量铅

制作了用桑色素作修饰剂的碳糊修饰电极 ,利用该电极为工作电极 ,建立了测定痕量铅的新方法。在甲酸钠 盐酸缓冲溶液 (pH 4 .9)中 ,在 - 0 .10V(vs .SCE)下搅拌富集 ,铅 (Ⅱ )与化学修饰碳糊电极表面的桑色素形成电活性络合物而吸附富集于电极表面 ,经 - 0 .85V(vs.SCE)静止还原后 ,阳极化线性扫描 ,在 - 0 .4 3V(vs .SCE)获得一灵敏的二次导数溶出峰。在最佳条件下分别富集 360s和 180s ,其二次导数峰电流与铅 (Ⅱ )浓度分别在 5 .0× 10 - 9～ 1.0× 10 - 7mol·L- 1和 2 0×10 - 8～ 1.0× 10 - 6 mol·L- 1两个范围内呈良好的线性关系 ,富集 6min ,检出限可达 1.0× 10 - 9mol·L- 1(S/N =3)。同时 ,探讨了电极反应机理。方法应用于尿铅测定 ,获得满意的结果     

流动注射不可逆双安培法测定二苯胺磺酸盐

通过配合0.5mol·L-1硫酸溶液中二苯胺磺酸根在一支铂电极上的氧化和0.05mol·L-1硫酸溶液中高锰酸根在另一支铂电极上的还原,构建了类似可逆电对的双安培检测体系,在两铂电极间电位差为OV时,实现了流动注射不可逆双安培法测定二苯胺磺酸盐。二苯胺磺酸盐溶液和高锰酸钾溶液被隔离在两个用盐桥相连的电极室中,以避免两者发生化学均相反应。在试验条件下,回路电流与二苯胺磺酸根的浓度在2.0×10-6-2.0×10-4mol·L-1范围内呈线性关系,检出限为7.0×10-7mol·L-1(S／N=3)。连续11次测定1.0×10-5mol·L-1二苯胺磺酸钠,电流值的RSD为0.52％。方法简单快速,可用于工业产品中二苯胺磺酸盐的测定。     

茜素紫修饰碳糊电极吸附阳极溶出伏安法测定痕量锑的研究

报道了采用茜素紫修饰碳糊电极测定痕量锑的阳极溶出伏安法。在 0 .0 3mol·L- 1邻苯二甲酸氢钾 盐酸缓冲溶液 (pH 2 .4 )中 ,通过开路富集 ,Sb(Ⅲ )与茜素紫形成络合物而富集于电极表面 ,然后交换介质至 0 .6mol·L- 1盐酸中 ,于 - 0 .6 0V还原后再进行阳极化扫描 ,于 - 0 .50V左右获得一灵敏的锑的溶出峰 ,二次导数峰电流与Sb(Ⅲ )的浓度在 4 .1× 10 - 9～ 2 .9× 10 - 7mol·L- 1范围内呈线性关系 ,检出限达 1.6× 10 - 9mol·L- 1。方法应用于水样中锑的测定 ,结果满意     

碳糊电极阳极溶出伏安法测定痕量铋(Ⅲ)

在 0 .2mol·L-1盐酸底液中 ,铋 (Ⅲ )与桑色素所形成的铋 (Ⅲ ) 桑色素络合物吸附于碳糊电极上 ,在 0 .30V(vs.SCE)预富集后 ,在 - 0 .30V处静止还原 30s ,再从 - 0 .30V到 0 .30V进行阳极化扫描 ,在 - 0 .0 8V左右获得一灵敏的铋溶出峰 ,其二次导数峰电流与铋 (Ⅲ )浓度在 2 .0× 10 -9～6 .0× 10 -6mol·L-1范围内呈线性关系 ,检出限达 1.0× 10 -9mol·L-1。探讨了电极反应机理 ,方法应用于胃药和锰盐中铋的测定 ,结果满意     

顺、反丁烯二酸在铅电极上的电还原特性

采用循环伏安、计时电量及电化学阻抗等方法, 研究了顺、反丁烯二酸在铅电极上的电化学还原行为, 获取了传递系数、表观活化能和扩散系数等动力学参数, 并讨论了电化学还原机理. 结果表明, 顺、反丁烯二酸在铅电极上的电还原过程均为二电子不可逆反应, 扩散过程是速率控制步骤; 反丁烯二酸(FA)的还原电位要比顺丁烯二酸(MA)高约0.1 V, 较顺丁烯二酸难还原; 0.04 mol·L-1顺、反丁烯二酸在0.1 mol·L-1硫酸介质中的扩散系数分别为7.96×10^-6和6.72×10^-6 cm2·s-1. 电化学阻抗研究表明, 在铅电极上顺丁烯二酸较反丁烯二酸有更好的反应活性, 在较低偏置电压下FA和MA的电化学还原过程受电子转移控制, 随着偏置电压的增加, 逐渐转变为扩散控制. 顺丁烯二酸和反顺丁烯二酸的不同空间结构, 使顺、反丁烯二酸在铅电极表面电还原行为存在差异.     

吡啶阳离子表面活性剂的示波极谱测定方法研究

在 0 .0 4mol·L- 1Na2 HPO4 KH2 PO4 (pH 8.0 )底液中 ,氯化十六烷基吡啶在汞电极上峰电位 - 1.35V(vs .SCE)处产生灵敏的还原波 ,其浓度在 0～ 0 .6mg·L- 1范围内与极谱波二阶导数的峰高 (H)呈正比 ,检出限 (3S/k)为 0 .0 1mg·L- 1。该极谱波具有吡啶阳离子表面活性剂的典型特征 ,特异性强 ,多种共存物质无干扰。用于生活饮用水中吡啶阳离子表面活性剂总量的测定 ,获得了满意的结果     

流动注射安培法快速测定食盐中碘

报道了在酸性溶液中 ,IO- 3可被过量的I- 还原 ,FI流动注射安培法快速测定食盐中碘的方法。溶解于蒸馏水中的食盐样品 (30 μl)注入pH 1的 0 .1mol·L- 1NaCl + 1× 10 - 3mol·L- 1KI的载液中。自行研制的壁喷玻碳电极安培流通检测池作为工作电极 ,电位为 + 0 .2V(vs.SCE)。该系统和反向 (注入KI)系统的线性范围均为 1× 10 - 6 ～ 1× 10 - 4mol·L- 1,检出限为 5× 10 - 7mol·L- 1,相对标准偏差为 0 .8% (n =37) ,样品测定的回收率为 97.6 %～ 10 4 % ,采样频率 90样·h- 1。通过Bernoull恒流瓶可获得无脉冲载流。     

在二甲亚砜中La—Fe合金膜电化学制备的研究

研究了二甲亚砜 (DMSO)中La3 和Fe2 在Pt ,Cu和Ni电极上的电化学行为。Fe2 在Pt电极上一步不可逆还原为Fe ,La3 在Pt电极上表现为准可逆电极过程。在 2 98K时 ,利用循环伏安法测定了 0 0 1mol·L- 1 FeCl2 0 1mol·L- 1 LiCl DMSO溶液中Fe2 的扩散系数、传递系数分别为 2 5 4× 10 - 6 cm2 ·s- 1 和 0 2 4;利用计时电流法测定了 0 0 1mol·L- 1 LaCl3 0 1mol·L- 1 LiCl DMSO溶液中La3 的扩散系数为 3 10×10 - 6 cm2 ·s- 1 。在铜电极上于 -1 75 0～ -2 45 0V (vs .SCE)下恒电位电解 ,可获得La含量达 2 2 7%～ 3 7 1%的La Fe合金膜 ;应用脉冲电解技术于 2～ 6mA·cm- 2 也可获得La Fe合金膜。这些合金膜是均匀的 ,粘附性好并有金属光泽     

Electrodeposition of the Charge-Transfer Complex Generated during Electrooxidation of o-Tolidine and the Effects of Coexisting Chondroitin Sulfate

The electrochemical quartz crystal microbalance (EQCM) technique was used to investigate the electrodeposition of the charge-transfer complex (CTC) generated during electrooxidation of o-tolidine (o-TD) in Britton-Robinson buffers and the effects of coexisting chondroitin sulfate (CS). A V-shaped frequency response to the cyclic voltammetric switching of o-TD indicated the precipitation and dissolution of the poorly soluble CTC, an oxidation intermediate, formed at the Au electrode during the redox switching of o-TD in a neutral or a weakly acidic medium (pH=4.07-6.50). The effects of potential scan rate, solution pH, and several supporting electrolytes were examined. The depth of the V-shaped frequency curves (-Δf_0V) was related to the supporting electrolyte used, with a decreasing sequence for −Δf_0V as 0.20 mol·L⁻¹ NaNO₃ > 0.20 mol·L⁻¹ NaClO₄ > 0.10 mol·L⁻¹ Na₂SO₄. The −Δf_0V response to the redox switching of the CTC/o-TD “couple” was enhanced by the introduction of CS because of the formation of the CTC-CS adduct, as also characterized and supported by UV-Vis and FTIR spectrophotometry. The molar ratio (x) of the CTC to CS in the adduct and the electrode-collection efficiency of the CTC (η) were estimated using EQCM. The values of −Δf_0V increased with the increase in CS concentration, with a linear range from 0.75 to 15.2 μmol·L⁻¹, and a detection limit down to 50 nmol·L⁻¹. The new method proposed for CS assay was characterized by a dynamically renewed surface of the detection electrode.     

Electrochemical Quartz Crystal Microbalance Studies on the Codeposition of Dextran Sodium Sulfate with the Charge‐Transfer Complexes Generated During Electrooxidation of Benzidine Derivatives

The electrochemical quartz crystal microbalance (EQCM) technique was used to investigate the electrochemistry of three benzidine derivatives, o‐tolidine (o‐TD), 3,3′,5,5′‐tetramethyl‐benzidine (TMB) and o‐dianisidine (o‐DA), in Britton‐Robinson (B‐R) buffer solutions with and without coexisting dextran sodium sulfate (DSS), respectively. During the anodic potential sweep from 0.1 to 0.7 V vs. SCE in pH 5.0 B‐R buffer solution containing o‐TD, the EQCM frequency was decreased during the first‐step oxidation of o‐TD and then increased to some extent during its second‐step oxidation, implying that a poorly soluble charge‐transfer complex (CTC) was produced here as an oxidation intermediate, and its precipitation and then dissolution at the EQCM Au electrode decreased and then increased the frequency. The depth of the V‐shaped time‐dependent frequency response (?Δf_0V) to the redox switching of the CTC/o‐TD couple (0.1–0.37 V vs. SCE) was notably enhanced in the presence of DSS, being due to the formation of a mass‐enhanced CTC‐DSS adduct via electrostatic affinity. Similar phenomena were evident in the TMB system, but the CTC behavior was not observed during o‐DA oxidation in the absence of DSS, namely, the EQCM frequency kept decreasing all the time, due probably to the too high lability of the CTC from o‐DA oxidation, and the coexistence of DSS could well stabilize this CTC and turn on its CTC behavior. The o‐TD system showed the highest sensitivity to DSS and was thus examined in detail. The mechanism for the CTC‐DSS interaction is discussed from EQCM, FT‐IR and UV‐vis data. The CTC‐based EQCM determination of DSS, which is featured by a dynamically renewed surface of the detection electrode, was thus proposed, with a linear range from 0.002 to 1.6 μmol L^?1 and a detection limit down to 0.7 nmol L^?1 (o‐TD system).     

电解液组成对尖晶石LiMn_2O_4中锂离子嵌脱过程的影响

运用电化学阻抗谱(EIS)研究了尖晶石LiMn2O4正极在1mol·L-1LiPF6-EC(碳酸乙烯酯)∶DEC(碳酸二乙酯)∶DMC(碳酸二甲酯),1mol·L-1LiPF6-EC∶DEC∶EMC(碳酸甲乙酯)和1mol·L-1LiPF6-EC∶DMC三种不同电解液中,-20-20℃范围内的阻抗谱特征随温度的变化.研究结果表明,温度强烈影响尖晶石LiMn2O4正极的阻抗谱特征,而电解液组成对尖晶石LiMn2O4正极阻抗谱特征的影响较小,但电解液组成对锂离子在尖晶石LiMn2O4正极中嵌入脱出过程相关动力学参数影响较大.测得尖晶石LiMn2O4正极在上述三种电解液中,锂离子迁移通过固体电解质相界面(SEI)膜的离子跳跃能垒平均值分别为7.60、16.40和18.40kJ·mol-1;电子电导率的热激活化能平均值分别为44.77、35.47和68.06kJ·mol-1;嵌入反应活化能平均值分别为52.19、46.19和69.86kJ·mol-1.     

血红蛋白在月桂酸修饰玻碳电极的电催化行为

研究血红蛋白在月桂酸修饰电极上的电化学行为,在0.02mol.L-1KH2PO4-Na2HPO4(pH=7)的缓冲液中,+0.6～-0.7V(vs.Ag/AgCl)电位范围内,Hb于该修饰电极产生不可逆还原电流峰.还原峰电流ip与v1/2呈线性关系,ip随溶液pH值和血红蛋白浓度的增加而增大,其浓度在1.00×10-8～5.00×10-9mol.L-1和1.92×10-6～2.06×10-7mol.L-1范围内分段呈线性变化关系.实验数据经进一步分析拟合,得到更精确的信息.该电极可作为检测血红蛋白的新型电化学生物传感器.     

邻苯二胺的电聚合及膜氧化还原过程的研究

石英晶体微天平;循环伏安法;邻苯二胺的电聚合及膜氧化还原过程的研究     

EQCM Study of Iridium Anodic Oxidation in H2SO4 and KOH Solutions

In the present study anodic oxidation of iridium layer formed thermally on a gold‐sputtered quartz crystal electrode has been investigated by electrochemical quartz crystal microgravimetry (EQCM) in the solutions of 0.5 M H₂SO₄ and 0.1 M KOH. The emphasis here has been put on the microgravimetric behavior of iridium as a metal, because a few previous EQCM studies reported in literature have been devoted to iridium oxide films (IROFs). The objective pursued here has been to elucidate the nature of the main voltammetric peaks, which occur at different ranges of potential in the solutions investigated. It has been found that anodic oxidation of iridium electrode in 0.5 M H₂SO₄ and 0.1 M KOH solutions is accompanied by irregular fluctuations of the electrode mass at 0.4 V<E<0.8 V followed by regular increase in mass at 0.8 V<E<1.2 V. The cathodic process initially, at 1.2 V>E>0.9 V, proceeds without any or with slight increase in electrode mass, whereas at E<0.8 V a regular decrease in mass is observed. It has been found that mass to charge ratio characterizing the processes of interest is 2 to 3 g F^?1in acidic medium, whereas in the case of alkaline one it is 4 to 6 g F^?1. The main pair of peaks seen in the voltammograms of Ir electrode in alkaline medium at E<0.8 V is attributable to redox transition Ir(0)→Ir(III), whereas those observed in the case of acidic medium at E>0.8 V should be related to the redox process Ir(0)→Ir(IV) going via intermediate stage of Ir(III) formation. As a consequence of these redox transitions, the gel‐like surface layer consisting of Ir(III) or Ir(IV) hydrous oxides forms on the electrode surface.     

金电极上放线菌素D的电化学行为及分析测定

应用方波溶出伏安法研究了放线菌素D在KH2PO4-Na2HPO4缓冲溶液中于金电极上的电化学行为以及酸度、预富集沉积电位、预富集沉积时间、方波频率、方波幅度、电位增量等的影响,优化测定参数,建立一种直接测定放线菌素D的电分析测定方法.在0.1～10.0μmol.L-1浓度范围内,放线菌素D与其方波溶出伏安氧化峰电流呈良好的线性关系,相关系数0.9991,检测限1.0×10-8mol.L-1.     

Motion of redox molecules in solution monitored by the highly-sensitive EQCM technique

The behavior of redox molecules in solution that was not detected by electrochemical techniques was measured by a highly-sensitive electrochemical quartz crystal microbalance (EQCM) technique that has been improved in this study to obtain a high sensitivity of EQCM measurement in solution. The improved EQCM technique allowed to monitor the motion of a redox molecule, that is an access of the molecule to an electrode surface and repulsion from the surface during redox. An EQCM technique currently in use has measured adsorption of redox molecules on an electrode surface or polymerization on the surface caused by a chemical reaction following redox, which exhibits an enough large mass change response to detect with an EQCM measurement. However, access and repulsion of redox molecule, which is a slight motion of the molecule near on electrode surface, has not been detected and investigated by an EQCM technique, because the mass change response seems to be very small. In this study, the redox behavior of methyl viologen on a bare gold surface, pyridinethiol surface and methylpyridinethiol surface was investigated. Although the three electrodes give the same cyclic voltammogram of methyl viologen, the three are different in QCM response recorded at the same time as the voltammetry. Access/repulsion of methyl viologen within an electrical double layer was monitored by the highly-sensitive EQCM technique.     

CS2与亚硝酸水溶液复相体系的激光闪光光解

利用激光光解-瞬态吸收技术研究了氮气饱和条件下CS2与亚硝酸水溶液复相体系的355nm光解机理.瞬态吸收光谱分析结果表明:CS2与·OH自由基快反应生成CS2OH,产生的CS2OH继续与HONO反应生成CS2OH-HONO加合物,其吸收峰分别为285,305,475,490和980nm,反应CS2OH+HONOCS2OH-HONO的二级速率常数为(2.79±0.05)×108L/(mol·s);230nm处的吸收峰归属为CS2NO+,其一级衰减速率常数为1.28×105s-1.     

高浓度V-H2O体系的溶解组分优势区域图和Pourbaix图

对25 ℃, 总V浓度cT(V)=1.0×10^-3 mol·L-1时的V-H2O 体系可能存在的组分进行热力学和电化学分析, 计算了各溶解组分的浓度, 运用“浓度比较法”作为判据, 确定液相和液相、液相和固相以及各固相间的边界线, 绘制了cT(V)=1.0×10^-3 mol·L-1时V-H2O 体系的溶解组分优势区域图和Pourbaix图. 与低浓度(cT(V)=1.0×10^-5 mol·L-1)的优势区域图比较发现, 在一定的温度和压力下, 总钒浓度对于钒阳离子的优势区影响不大, 但对钒酸根阴离子的优势区影响显著; 随着总钒浓度的增大和酸化程度的逐步加强, 钒酸根阴离子会发生一系列复杂的质子化和聚合反应; 总钒浓度越高、酸性越强, 多核钒酸根阴离子越稳定.