Square Wave Voltammetry for Analytical Determination of Cadmium in Natural Water Using Ca10(PO4)6(OH)2-Modified Platinum Electrode

This paper reports on the development of a novel electrochemical assay for cadmium (II) in natural water, which involves the use of disposable hydroxyapatite modified platinum electrode (HAP/Pt). Cadmium (II) was preconcentrated on the surface of the modified electrode and adsorbed onto HAP and oxidized at E = –680 mV. The HAP-modified platinum electrode exhibited superior performance in comparison to the plati- num electrode and surprisingly, yielded a higher electrochemical response. The best defined anodic peak was obtained with 0.2 mol L-1 KNO3 pH 5.0 after 25 min of accumulation time. Using these conditions, the cali- bration plot was linear over the range 1 × 10?8 to 5 × 10?6 mol L-1 Cd2+. The precision was examined by car- rying out eight replicate measurements at a concentration of 2.5 ×10?5 mol L-1;the coefficient of variation was 2.9%. The method was applied to the determination of the analyte in river water samples. The interfere- ence of other metal ions on the voltammetric response of Cd(II) was studied. The HAP films was clearly ob- served in the SEM images and characterized by X-ray diffraction, IR spectroscopy and chemical analysis.

Osteryoung square wave voltammetric determination of lactose in food samples by a derivative procedure

A method for determination of lactose in food samples by Osteryoung square wave voltammetry （OSWV） was developed. It was based on the nucleophilic addition reaction between lactose and aqua ammonia. The carbonyl group of lactose can be changed into imido group, and this increases the electrochemical activity in reduction and the sensitivity. The optimal condition for the nucleophilic addition reaction was investigated and it was found that in NH4C1-NH3 buffer of pH 10.1, the linear range between the peak current and the concentration of lactose was 0.6-8.4 mg L-l, and the detection limits was 0.44 mg L- 1. The proposed method was applied to the ＇determination of lactose in food samples and satisfactory results were obtained.

Determination of ziram in vegetable samples by square wave voltammetry

The electrochemical behaviour and electrode reaction mechanism of ziram （zinc-dimethyl dithiocarbamate） on a hanging mercury drop electrode were investigated in Britton-Robinson （B-R） buffer by using cyclic and square wave voltammetry （SWV）. Based on these studies a voltammetric method for determination of ziram wasdeveloped and applied to determine the ziram in synthetic and spiked vegetable samples, satisfactory results were obtained in both cases.

现代方波伏安法(SWV)测定辉长石中微量钒的研究

本文使用美国ＰＡＲ公司ＥＧΣＧ３８４Ｂ多功能极谱仪建立了ＳＷＶ法测定辉长石中微量钒的方法。Ｎａ２Ｏ２溶样、水浸溶块、ＨＡｃ－ＮａＡｃ体系，起始电位－０．５０Ｖ，终止电位－１．５０Ｖ，钒峰电位－１．０４Ｖ，灵敏度比经典极谱法提高２个数量级，在所选测定体系条件下，钒峰高随浓度增大而明显增高，且峰电位再现性好、峰形稳定，并用该法对实际样品测定，效果满意。

多巴胺在FcA/Nafion/GCE上的电化学行为及其SWV测定应用

研究了多巴胺（Dopamine，DA）在二茂铁乙酸（Ferrocenyl Acetic Acid，FcA）和Nation聚合物薄膜修饰玻碳电极（FcA／Nation／GCE）上的电化学行为，测定了DA在该修饰电极上的动力学参数，并用方波伏安法（SWV）对DA在FcA／Nation／GCE上的测定应用进行了研究．结果表明，与GCE相比，DA在FcA／Nation／GCE上的峰电流增大约10倍，氧化峰电位负移60mV，表明FcA／Nation／GCE对DA有良好的电化学催化作用；同时测得DA在FcA／Nation／GCE上的电子转移系数口为0．44，反应速率常数k。为0．106cm／s，表观扩散系数D0为5．4×10^-6cm^2／s．用SwV方法测得DA浓度在1．0×10^-5～2．0×10^-3mol／L范围内氧化峰电流（Jpa）与其呈良好的线性关系，线性拟舍方程为Jpa（μA）=47．524＋16．508c（10mol／L），相关系数R=0．9989，检出限为1．0×10^-6mol／L，相对标准偏差为0．9％～1．1％，回收率为97．5％～100．1％．该测定方法简单快捷，测定结果令人满意．

CuO-nanoparticles modified carbon paste electrode for square wave voltammetric determination of lidocaine: Comparing classical and Box–Behnken optimization methodologies

In this research, copper oxide nanoparticles modified carbon paste electrode was developed for the voltammetric determination of lidocaine. The square wave voltammogram of lidocaine solution showed a well-defined peak between ＋0.5 and ＋1.5 V. Instrumental and chemical parameters influencing voltammetric response were optimized by both one at a time and Box–Behnken model of response surface methodology. The results revealed that there was no significant difference between two methods of optimization. The linear range was 1–2500 μmol L^-1（Ip= 0.11 C（LH）＋ 17.38, R^2= 0.999）. The LOD and LOQ based on three and ten times of the signal to noise（S/N） were 0.39 and 1.3 μmol L^-1（n = 10）,respectively. The precision of the method was assessed for 10 replicate square wave voltammetry（SWV）determinations each of 0.05, 0.5 and 1 μmol L^-1 of lidocaine showing relative standard deviations 4.1%,3.7% and 2.1%, respectively. The reliability of the proposed method was established by application of the method for the determination of lidocaine in two pharmaceutical preparations, namely injection and gel.

Electrooxidation of sulfanilamide and its voltammetric determination in pharmaceutical formulation,human urine and serum on glassy carbon electrode

For the first time, sulfanilamide(SFD) was determined in otologic solution, human urine and serum by electroanalytical techniques on glassy carbon electrode(GCE). The cyclic voltammetry(CV) experiments showed an irreversible oxidation peak at t 1.06 V in 0.1 mol/L BRBS(p H ? 2.0) at 50 m V/s. Different voltammetric scan rates(from 10 to 250 m V/s) suggested that the oxidation of SFD on the GCE was a diffusioncontrolled process. Square-wave voltammetry(SWV) method under optimized conditions showed a linear response to SFD from 5.0 to 74.7 μmol/L(R ? 0.999) with detection and quantification limits of 0.92 and3.10 μmol/L, respectively. The developed SWV method showed better results for detection limit and linear range than the chronoamperometry method. It has been successfully applied to determine SFD concentration in pharmaceutical formulation, human urine and serum samples with recovery close to 100%.

ADDITIVE SQUARE WAVE VOLTAMMETRY FOR COMPLEXING ADSORPTIVE CATALYTICAL SYSTEMS

The voltammetry for complexing adsorptive catalytical systems (CACS) has high sensitivity due to the coexistence of the adsorptive reducing current and the catalytical current. However, no study has been made on the case in which square wave voltammetry is used.

Ac voltammetric and square wave voltammetric study of the self-assembled monolayers of thiol-functionalized viologen derivative

Electroactive self-assembled monolayers (SAMs) containing viologen group are formed through the adsorption of thiol-functionalized viologen compound CH3(CH2)(9)V2+(CH2)(8)SH, where V2+ is N,N'-dialkylbipyridinium (i.e. a viologen group), onto gold electrodes from methanol/water solution and its electrochemical behavior is investigated ty Ac voltammetry and square wave voltammetry, which have the high sensitivity against background charging. The viologen SAM formed is a sub-monolayer and the normal potentials corresponding to the two successive one-electron transfer processes of the active centers (viologen) are -360 mV and -750 mV (vs. Ag/AgCl) in 0.1 mol/L phosphate buffer solutions (pH 6.96) respectively, and the standard electron transfer rate constant is 9.0 s(-1). The electrochemical behavior of this SAM in various solutions has been preliminarily discussed.

基于刃天青的电化学方波伏安法快速鉴别大肠杆菌的耐药性

目的:评价5株食源性大肠杆菌临床分离株对环丙沙星、庆大霉素和氨苄西林的抗生素耐药性。方法:基于细菌能量代谢过程中的电子传递理论,引入刃天青作为氧化还原探针,建立了一种基于刃天青介导的大肠杆菌耐药性快速鉴别的电化学方波伏安法(square wave voltammetry,SWV)。结果:在1.69×10^(2)~1.69×10^(8)CFU/mL范围内,大肠杆菌浓度与刃天青氧化峰电流(I)之间存在较好的线性关系,回归方程为Y=-0.1560 X-2.9655,R^(2)=0.9775;在进行大肠杆菌耐药性测定时,参考美国临床和实验室标准协会制定的药敏试验标准,以刃天青的氧化峰电流(I_(0))和大肠杆菌直接与刃天青作用后得到的氧化峰电流(I_(-a))作为对照,测定大肠杆菌用抗生素处理后与刃天青作用得到氧化峰电流(I_(+a)),引入细菌活性值V_(ETA)作为电化学方波伏安法鉴别细菌耐药性的指标,建立了刃天青介导的大肠杆菌电化学快速药敏试验方法;运用建立的方法检测了5种食源性大肠杆菌临床分离株对3种抗生素的耐药性,以V ETA=50作为判断细菌敏感和耐药的临界值,均得到与纸片扩散法结果相符的药敏试验结果,而纸片扩散法报告结果需18 h,该法仅需2 h。结论:建立的基于刃天青介导的大肠杆菌耐药性快速鉴别的电化学方波伏安法能够准确且快速检测5株食源性大肠杆菌临床分离株对环丙沙星、庆大霉素和氨苄西林的抗生素耐药性。

基于氮掺杂介孔碳修饰玻碳微球糊电极的双酚A电化学传感器的构建及性能研究

制备了一种由氮掺杂介孔碳修饰的玻碳微球糊电极,用于双酚A的灵敏、快速检测。利用循环伏安法对修饰电极进行了表征,采用方波伏安法研究了双酚A在修饰电极上的电化学行为;根据不同扫速下峰电流与扫速的关系讨论了双酚A在电极表面的反应过程。在最优的实验条件下,双酚A的响应电流与浓度在0.3~2μM和2~30μM范围内时呈线性关系,检测限是0.01μM(S/N=3)。该方法具有良好的重现性和抗干扰性,可用于实际样品的检测,样品回收率为97.5%~101.5%。

基于Fe_(3)O_(4)-MoS_(2)-全氟磺酸纳米复合材料的铅离子电化学传感器

采用Fe_(3)O_(4)-MoS_(2)-全氟磺酸复合材料修饰玻碳电极(GCE),基于电化学传感原理,使用阳极方波伏安法检测水中微量的铅离子。通过扫描电子显微镜(SEM)、能量色散X射线光谱仪(EDS)、Raman光谱分析仪和X射线光电子能谱仪(XPS)进行物理表征。结果表明Fe_(3)O_(4)已较均匀地分布在MoS_(2)上。为了得到良好的实验效果,优化醋酸盐(Hac-NaAc)缓冲溶液的pH值为3.6,最佳沉积时间为120 s,最佳沉积电位为-0.6 V,在滴加5μL的Fe_(3)O_(4)-MoS_(2)和5μL的全氟磺酸条件下进行测试,实验结果表明在0.1~0.6μmol·L^(-1)铅离子浓度范围,Fe_(3)O_(4)-MoS_(2)-全氟磺酸-GCE传感器的线性度良好,灵敏度和检测限分别为25.05μA/(μmol·L^(-1))和0.11μmol·L^(-1)。该检测方法快速便捷,具有低成本、高效率和易操作的特点。

Indirect Electroanalysis of 3-Methyl-4-Nitrophenol in Water Using Carbon Fiber Microelectrode Modified with Nickel Tetrasulfonated Phthalocyanine Complex

Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.

Square wave volt-coulometry

FOR a long time, people pay particular attention to the way to decrease the charging current and improve the Faraday current in the modern square wave voltammetry (SWV), but the effects of random noise on analytical result are ignored. However, it is impossible to avoid the random noise absolutely in the measuring process. Especially, when the concentration is low, the signal is affected seriously by the random noise and it is difficult to get a lower detection limit. So it is necessary to know how to decrease the random noise in order to get a lower detection limit, while trying to find out how to decrease the charging current. A new sampling technique using the square wave potential scan is proposed to smooth the random noise and decrease the detection limit in SWV. The foundation of this new method comes from one of the laws of mathematical statistics; that is, the positive and negative probable errors in a group of detected data exist equally and then the sum of all the errors is ze-

尿酸在普鲁士蓝修饰电极上的电化学行为及其分析应用

用恒电位电解法制备了普鲁士蓝修饰玻碳电极,研究了尿酸(UA)在该电极上的电化学行为,并提出了一种新的用于检测UA的方法.在0.1 mol/L(pH 5.0 )的醋酸缓冲溶液中,0.100 mol/L KCl 作为支持电解质,UA在普鲁士蓝修饰电极上于0.470 V处产生一灵敏的氧化峰,方波伏安法测定其氧化峰电流与UA浓度在2.5×10-6～2.0×10-4 mol/L范围内呈良好的线性关系,相关系数为0.9986,检出限为1.1×10-6 mol/L.该电极制作简单,重现性良好,可用于UA的测定.

安乃近在蒙脱土修饰电极上的电化学行为及测定

制备了蒙脱土修饰电极，并采用循环伏安法研究了安乃近在该电极上的电化学行为。结果表明，该电极过程是一受扩散控制的不可逆过程。用方波溶出伏安法优化了实验参数，测定了浓度与峰电流Ipa的线性关系，发现Ipa与安乃近浓度在2．0×10^-6～8．0×10^-5mol·L^-1之间呈良好的线性关系，其线性回归方程为：Ipa（μA）=0．07784—15443．54c（μmol·L^-1），r=-0．9993，检出限可达1．12×10^-6mol·L^-1，回收率为94．0％～108．25％。该方法可用于药物中安乃近含量的测定。

方波伏安法间接测定壳聚糖的研究

建立了以茜素红(AR)为电活性探针方波伏安法间接测定无电活性的壳聚糖(CS)的新方法。在0 1mol/LHAc＿NaAc(pH4 5)缓冲溶液中,AR与CS＿AR在GCE上均能形成一准可逆的吸附伏安峰(Vpc=-0 46V,Vpa=-0 41V)。实验表明,CS在低浓度(1 25×10-8～2 5×10-7mol/L)和高浓度(2 5×10-7～1 25×10-5mol/L)的条件下对体系的峰电流分别具有线性增敏和减敏效应。采用标准加入法测定了不同样品中壳聚糖的含量,其回收率在97 33%～102 00%之间,结果满意。

银掺杂改性蒙脱土修饰电极上对苯二酚的电化学行为与测定

利用十八烷基三甲基溴化铵（STAB）和银氨溶液制备了银掺杂改性蒙脱土，并用X射线衍射法、扫描电镜法和交流阻抗法对其进行表征。用循环伏安法（CV）研究了对苯二酚在银掺杂改性蒙脱土修饰电极上的电化学行为，测定了部分动力学参数。结果表明，对苯二酚在电极上的阳极过程受吸附-扩散混合控制，阴极过程受扩散控制，转移的电子数n和质子数m均为2，传递系数α=0．6588，β=0．3412，电极有效面积Aeff=0．0264cm^2，扩散系数D=6．34×10^-5cm^2／s。用方波伏安法（SWV）研究了对苯二酚浓度与峰电流之间的线性关系，在优化实验条件下，对苯二酚浓度在4．0×10^-6-5．0×10^-4mol／L范围内与峰电流呈线性关系，检出限为1．13×10^-7mol／L，用该方法测定了实际水样中对苯二酚的含量，加标回收率为100％～108％。该修饰电极具有良好的重复性与稳定性。

碳纳米管传感器方波伏安法检测环境水样中的百草枯

制备了多壁碳纳米管修饰玻碳电极，采用循环伏安法等方法研究了农药百草枯在修饰电极上的电化学特性，建立了一种新的检测百草枯的电化学分析方法。在最佳实验条件下，用方波伏安法检测百草枯，其响应电流与百草枯的浓度在5．38×10^-7～2．37×10^-4mol／L范围内有很好的线性关系，检出限为5．0×10^-7mol／L。用此方法检测了环境水样中的百草枯。

铂纳米颗粒修饰电化学DNA传感器检测大豆中转基因成分

用电沉积方法将铂纳米颗粒修饰在玻碳电极表面,然后将花椰菜花叶病毒35S启动子ssDNA片段直接吸附在铂纳米颗粒上,制成特异的电化学DNA传感器。用扫描电子显微镜和循环伏安法对修饰铂纳米颗粒电极进行了表征。ssDNA探针与互补目的ssDNA杂交,以[Co(phen)3]3+(phen=1,10-Phe-nanthroline)为杂交指示剂,用方波伏安法进行检测,表现出良好的响应信号。与在裸玻碳电极上修饰的探针相比,测定目的基因的灵敏度显著提高。传感器对互补目的ssDNA检测的线性范围为2.14×10-9～2.14×10-7mol/L;检出限为1.0×10-9mol/L,与3个碱基错配的DNA序列杂交,观察不到明显的杂交信号。样品DNA经HindⅢ非限制性内切酶酶切后测定,杂交检测信号增大。用传感器检测含量不同的转基因大豆DNA和非转基因大豆DNA的混合溶液,杂交前后的电流差与转基因DNA的含量呈良好线性关系。连续5次测量含有100%转基因大豆DNA杂交后的电信号,相对标准偏差为5.89%,固定探针的电极再生后可重复使用8次。