Amperometric detection of gold by differential pulse voltammetry using a DNA biosensor

A DNA biosensor with [Ru（DA-bpy）3]Cl2（DA-bpy：4,4＇-diamino-2,2＇-bipyridine） （RuL） as the electrochemical probe was prepared on pyrolytic graphite electrode （PGE） through the supramolecular interaction between RuL complex and DNA template. Cyclic voltammetry of RuL-DNA film showed a pair of stable and reversible peaks corresponding to the Ru（Ⅲ）/Ru（Ⅲ） redox potential of-0.165 V versus AglAgCl in pa 7.4 0.1 mol·L^-1Tris-HCl. The electron transfer was expected across the double-strand DNA by an ＂electron tunneling＂ mechanism. When the DNA biosensor was immerged in gold （Ⅲ） buffer solution, the current peak signal （I） of the RuL-DNA supramolecular depressed and △I was linear in the concentration range of Au ion from 1×10^-7 to 2×10^-5 mol·L^-1 with a regression coefficient of 0.9879. The detection limit was 5×10^-8 mol·L^-1. The developed procedures were applied to the analysis of synthetic samples of real materials with good sensitivity and selectivity.

Determination of trace amounts of morphine in human plasma by anodic adsorptive stripping differential pulse voltammetry

New adsorptive anodic differential pulse stripping voltammetry method for the direct determination of morphine at trace levels in human plasma of addicts is proposed.The procedure involves an adsorptive accumulation of morphine on a HMDE,followed by oxidation of adsorbed morphine by voltammetry scan using differential pulse modulation.The optimum conditions for the analysis of morphine are pH 10.5,Eacc of -100 mV（vs.Ag/AgCl）,and tacc of 120 s.The peak current is proportional to the concentration of morphine,and a Linear calibration graph is obtained at 0.01-3.10μg mL^-1.A relative standard deviation of 1.06%（n=5）was obtained,and the limit of detection was 3 ng mL^-1.The capabiLity of the method for the analysis of real samples was evaluated by the determination of morphine in spiked human plasma and addicts human plasma with satisfactory results.

Differential Pulse Voltammetric Simultaneous Determination of Paracetamol and Omnipaque on Boron Doped Diamond Electrode: Application to Natural Tomato, Carrot, Cucumber Juices and Wastewater

This article describes the use of a boron-doped diamond electrode (BDDE) as an electrochemical sensor for the simultaneous determination of omnipaque (OMP) and paracetamol (PCM) in perchloric acid medium (HClO4 0.1 M) and in complex matrices such as tomato, carrot and cucumber juices and waste water from the Treichville University Hospital. Voltammetric studies allowed us to have well-defined oxidation peaks at distinct potentials of OMP (E = 0.5 V/SCE) and PCM (E = 0.7 V/SCE). Under optimized conditions, well-defined quantities of OMP and PCM, introduced simultaneously by metered additions, gave linear responses in concentration ranges of 259.8 - 467.2 μM for OMP and 58.73 - 116.3 μM PCM. The detection limits obtained are 7.23 μΜ and 3.6 μΜ respectively for OMP and PCM with recovery rates between 85.8% ± 0.1% and 92.6% ± 0.1% for OMP and between 99.9% ± 0.1% and 101.2% ± 0.4% for the PCM. This technique has been successfully used to simultaneously detect these pharmaceuticals in these complex environments. It allows recovery of OMP and PCM respectively up to 97.5% ± 0.0% and 91.6% ± 0.3% in tomato juice;100.0% ± 0.0% and 95.2% ± 0.2% in carrot juice;101.4% ± 0.1% and 97.3% ± 0.3% in cucumber juice;100.1% ± 0.9% and 100.9% ± 0.1% in wastewater. The relevance of this technique for the simultaneous detection of OMP and PCM in tomato, carrot, cucumber juices and in waste water can be studied in the context of the contamination of certain fruits and vegetables by the substances organic pharmaceuticals released into the environment without prior treatment.

Electrochemical Determination of Alkaline Phosphatase in Human Serum by Differential Pulse Voltammetry

Differential pulse voltammetry(DPV) was applied to the determination of alkaline phosphatase(ALP) activity in human serum with phenyl phosphate as the substrate. Phenyl phosphate can enzymatically be hydrolyzed to produce phenol which is quantified by DPV at +660 mV(vs.Ag/AgCl) in the concentration range of 2.0_100 μmol/L. The standard curve for ALP is linear over the range from 0.06 to 1000 U/L with a relative standard deviation of 3.0%. The conditions for the enzymatic reaction and voltammetric detection were optimized and the kinetic constants were also examined.The human serum samples were tested by this method and the results were in good agreement with those obtained by the routine p-nitrophenyl phosphate spectrophotometric method.

Detection of Pesticide Metsulfuron-methyl in Drinking Water by Differential Pulse Cathodic Stripping Voltammetry

Differential pulse cathodic stripping voltammetry was used to determine pesticide metsulfuron-methyl on a suspended mercury electrode.Specific experimental parameters,such as the pH of Britton-Robinson buffer,accumulation time,accumulation potential,and initial potential were optimized.The results show that a typical reduction peak appeared when pH was 2.0-4.0 and initial potential ranged from-0.75 to-1.0 V.To obtain the stripping signal of the best reduction peak,it is determined that the best pH was 2.0.The detection limit of the method was only 0.04 mg/L,and it had good selectivity and high accuracy,so the method has high sensitivity.In the analysis of actual drinking water,the recovery rate of metsulfuron-methyl could reach 93%-101%.

Study on Water-Soluble Organic Reducing Substances. I. Determination of Organic Reducing Substances by Differential Pulse Voltammetry

A new method was proposed for study of organic reducing substances in soils.According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances,the working conditions of differential pulse voltammetry (d.p.v.)for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode,1M Ag-AgCl electrode with large area as reference electrode,0.2M NH4Ac as supporting from -0.5 to +1.2 voltage(vs.M Ag-AgCl).The peak current proportional to the concentration of reducing substances,and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base,respectively.These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.

Indirect Differential Pulse Voltammetric Determination of Aluminum by a Pyrocatechol Violet-Modified Electrode

A PCV-modified electrode was simply prepared by dip-coating a pyrolytic graphite electrode in a NaAc-HAc buffer solution of PCV. The peak currents of differential pulse voltammograms (DPV) decrease with the addition of Al and the peak potentials remain the same. The decreasing of Delta i(p) is linear with Al concentration in the range of 1 x 10(-8) similar to 1 x 10(-7) mol/L. The detection limit is 5 x 10(-9) mol/L and the relative standard deviation for 4 x 10(-8) mol/L Al is 2.9% (n=8). No serious interference was found. The determination of Al in water samples is reported.

4-methoxy-2,6-bis(3,5-dimethylpyrazoyl)-1,3,5-triazine modified carbon paste electrode for trace Cu(Ⅱ) determination by differential pulse volt-ammetry

A differential pulse voltammetric method was developed for the sensitive andselective determination of Cu(II) at 4-methoxy-2,6-bis(3,5-dimethylpyrazoyl)-l,3,5-triazine modifiedcarbon paste electrode in 0.05 mol/L KHC_8H_4O_4 solution (pH = 4.02). The oxidation peak of Cu(II)was observed at 0.065 V(vs Ag/AgCl) by scanning the potential in positive direction. The analysisprocedure consisted of an open circuit accumulation step in stirred sample solution. It was followedby medium exchange to a clean solution and subsequently an anodic potential scan was affected toobtain the voltammetric peak. The current was proportional to the concentration of the Cu(II) ion ina range of 1 X 10^(-7) -1 X 10^(-4) mol/L for 6 min accumulation; the most of metal ions did notinterfere with the determination. The developed method was applied to Cu (II) determination incoal-ash sample, the results agreed with that of atomic adsorption spectroscopy (AAS).

DIFFERENTIAL PULSE VOLTAMMETRIC DETERMINATION OF 3,3'5,5'-TETRAMETHYLBENZIDINE AND ITS ANALOGUES WITH A GLASSY CARBON ELECTRODE

The differential pulse voltarametric ( DPV ) method with a glassy carbon electrode was used for the determination of 3,3' 5,5'-tetramethy lbenzidine ( TMB ) , o-tolidine and benzidine in the acidic media. The pulse amplitude, interval time and scan rate of DPV are optimized to be 50 mV, 0.5 s and 10 mV/s, respectively, The peak current is proportional to the concentration of TMB and its analogues, the linear range is from 10^-8mol/l to 10^-4 mal/l, The electrochemical behaviour of the compounds is discussed, The chemical poisons can be determined directly, or indirectly by the extraction in the waste water of chemical industry and laboratory,

差分脉冲伏安法间接检测氯吡脲

氯吡脲可以抑制铁氰化钾的还原反应,基于此建立了差分脉冲伏安法(DPV)间接测定氯吡脲浓度的新方法。为减小试验工作量,本文选取试验次数少、可靠性强的均匀设计法,采用其中的表U1*0(108),对包括支持电解质硫酸钾浓度、铁氰化钾浓度、多壁碳纳米管的浓度、铅笔芯的有效长度、扫描电位范围和富集时间等6个条件进行了6因素10水平优化试验。在最佳条件下,铁氰化钾的DPV还原峰电流下降值ΔI与氯吡脲浓度在0.75~1.75μmol/L范围成正比,检测限为4.20×10^(-2)μmol/L,氯吡脲体系可能共存的物质不干扰测定。采用本方法对施加过氯吡脲的猕猴桃果实进行测定,与标准方法LC-MS的检测结果一致。

改性氮化碳/铜基MOF纳米复合材料修饰电极对草甘膦的电化学检测研究

使用铜基MOF材料(Cu-BTC)和含羰基杂环的介孔氮化碳(CN)合成的纳米复合材料修饰电极构建了电化学传感器,采用差分脉冲伏安法检测水环境中的草甘膦。该传感器的检测机理是通过Cu^(2+)与草甘膦发生络合反应,使得响应电流发生降低。所制备的材料通过扫描电子显微镜、透射电子显微镜、X射线衍射技术、X射线光电子能谱和傅立叶变换红外光谱等进行表征,确认了其形貌与结构。实验结果表明,该传感器具有高的灵敏度,检出限为0.1576 pg/L,线性范围为10^(-6)~10^(-12)g/L,对草甘膦具有良好的选择性。当评估该传感器以检测实际水样中的草甘膦时,回收率达到94%~107%,表现出很高的准确性和实用性。

基于差分脉冲伏安法快速检测花椒油树脂中的麻味物质

麻味物质含量是花椒油树脂的重要品质指标,文章基于电化学原理中的差分脉冲伏安法首次建立了一种采用未修饰的丝网印刷电极测定花椒油树脂中麻味物质的快速检测方法,通过优化电化学工作站中的富集时间、电压以及待测液中的甲醇占比、pH值,并以紫外分光光度计检测法为对照构建出了该方法。结果表明,以未修饰的丝网印刷电极检测花椒油树脂中麻味物质的适宜条件:富集时间为120 s,富集电压为0.2 V,甲醇在待测液中占比小于5%,pH值为1,2,3,山椒素的电流值与其浓度在2~50 mg/L范围内呈良好的线性关系(R^(2)=0.999),加标回收率在97.60%~108.40%之间,检出限为0.22 mg/L。经验证,该方法与行业标准GH/T 1290—2020方法具有良好的检测一致性(RSD=4.75%),建立的快速检测方法既具有操作简单、方便快速的优点,又兼具传统方法的准确性与重复性,因此可以作为花椒及其制品中麻味物质的快速检测方法进行科学研究与企业生产实践,且有望基于该方法开发出便携式麻味物质快速检测仪器。

大肠杆菌快速检测系统设计与实现

食品安全是民生问题之一,与人们的生活密不可分。大肠杆菌O157:H7是一种典型的致病菌,传统的大肠杆菌检测方式比较耗时且需专业的操作人员,如何能进行大范围、快速、易操作的大肠杆菌检测是亟待解决的问题。通过差分脉冲伏安法检测大肠杆菌浓度与电流的关系,设计电化学横向流动免疫分析平台,提出基于电化学和嵌入式单片机技术的快速检测方法。经测试,该系统的检测误差小于4.5%,系统重复误差小于3.7%,最低检测浓度达到102 CFU/mL,检测时间为10 min,可有效用于大肠杆菌的快速检测。

ITO电极在水中超低水平Cd^(2+)检测中的应用

为了检测水质中痕量水平的Cd^(2+),以氧化铟锡(ITO)薄膜电极为工作电极,铂片和饱和甘汞电极(SCE)分别为对电极和参比电极,构建了针对Cd^(2+)的化学传感器。采用差分脉冲伏安法(DPV)对构筑的化学传感器在含Cd^(2+)的乙酸溶液(pH=4.5)中的灵敏度、选择性、检出限和长期稳定性进行了评价。研究结果表明,所构筑的化学传感平台对Cd^(2+)的灵敏度为24.61μA/μmol/L,Cd^(2+)的校准曲线方程为Y=24.61X+11.145,相关系数(R2)为0.994,检出限(LOD)为0.06μmol/L;干扰性实验结果表明,Zn^(2+)、Cu^(2+)、Pb^(2+)、Ag^(+)4种金属离子对Cd^(2+)的检测干扰较小;稳定性实验结果表明,所构建的针对Cd^(2+)的化学传感器具有良好的稳定性;实际水样检测表明,构建的化学传感器可以用来对自来水中Cd^(2+)进行检测。研究显示,所构建的针对Cd^(2+)的化学传感器可以用来检测水质中痕量Cd^(2+)。

基于Pd/g-C_(3)N_(4)的电化学传感器同时检测木犀草素和香兰素

石墨相氮化碳(g-C_(3)N_(4))是近年来被广泛关注的非金属半导体材料,其化学性质稳定、制备简单、成本低,但比表面积小,导电性能不理想限制了它在电化学传感器中的应用。为解决这一问题本工作通过掺杂改性的方式在g-C_(3)N_(4)表面修饰金属纳米颗粒。首先,以热缩聚合成法制备管状g-C_(3)N_(4),再通过水热法制备钯(Pd)掺杂g-C_(3)N_(4)(Pd/g-C_(3)N_(4))复合材料,并构建Pd/g-C_(3)N_(4)修饰电极应用于木犀草素(LU)和香兰素(VA)的同时测定。采用扫描电镜(SEM)、能谱(EDS)、X-射线衍射(XRD)对Pd/g-C_(3)N_(4)的形貌、结构、纯度进行表征。采用循环伏安法(CV)、差分脉冲伏安法(DPV)对LU和VA在Pd/g-C_(3)N_(4)修饰电极上的电化学行为进行研究。在最优条件下,采用DPV法同时检测LU和VA,峰电流与浓度呈线性关系,线性范围均为0.5~10μmol/L,检出限均为0.1μmol/L。

Cu@ZIF-67纳米材料的制备及其电化学传感应用

本研究采用化学法合成了Cu@ZIF-67纳米复合材料,使用能谱仪和扫描电镜对其化学组成和表面形貌进行了表征。将该纳米复合材料修饰在玻碳电极表面,构建了一种电化学传感器。通过循环伏安法和差分脉冲伏安法测定了该电化学传感器的性能,结果表明,该传感器对多巴胺(DA)具有良好的催化活性,检测DA的线性范围在0.1~800μmol·L^(-1),检出限为0.03μmol·L^(-1)(S/N=3)。本研究构建的电化学传感器具有线性范围宽,检测限低,稳定性高等优点,为人体内多巴胺含量的检测提供了一种有效的方法。

差分脉冲伏安法对果蔬中亚硝酸盐和抗坏血酸的同时测定

采用对苯二酚(Hydroquinone,HQ)催化甲烷氧化菌素(Methanobactin,Mb)还原氯金酸合成纳米金(Gold Nanoparticles,AuNPs),利用电沉积法将Mb@AuNPs修饰到裸金电极表面,制备Mb@AuNPs/Au电极。采用差分脉冲伏安法对亚硝酸盐和抗坏血酸进行同时测定并对条件进行优化,结果表明:电极组装条件为电沉积扫速100 mV/s、扫描圈数为40圈;检测体系为浓度0.20 mol/L pH6.5的磷酸盐缓冲溶液,在2~5600μmol/L和1~6000μmol/L的线性范围内,Mb@AuNPs/Au对亚硝酸盐和抗坏血酸同时检测的氧化峰电流与浓度呈良好的线性关系(R^(2)>0.9928),检出限分别为0.31和0.57μmol/L。实际样品中亚硝酸盐和抗坏血酸的加标回收率范围分别为92.59%~109.26%、90.01%~103.51%,表明该方法具有良好的重现性和稳定性,可用于果蔬中亚硝酸盐和抗坏血酸的同时测定。

便携式黄曲霉毒素B1检测系统设计与试验

为实现农副产品中黄曲霉毒素B1 (AFB1)的现场快速检测,设计了一款基于差分脉冲伏安法(Differential pulse voltammetry,DPV)、以STM32F103ZET6为核心处理器的便携式检测系统。系统主要包括硬件检测设备和手机App两部分,二者通过Wi-Fi通信连接。硬件检测设备主要包括DPV波形生成电路、恒电位电路及微电流检测模块;上位机App在安卓环境下开发,主要完成信号采集、数据存储等任务。应用实验室自制的AFB1传感器,在0.1 fg/ml~100 pg/ml范围内系统可以对AFB1实现有效检测。标准溶液中的测试结果与电化学工作站CHI760e相比,最大相对误差为7.37%。对加入不同浓度AFB1的花生油样品进行检测,以CHI760e检测结果为标准,回收率为96.8%~106%;对发霉程度不同的花生样品中进行测试,与CHI760e相比,最大相对误差为7.10%。本便携式检测系统在农副产品中AFB1的现场快速检测中具有广阔的应用前景。

基于纳米复合材料修饰的玻碳电极检测血清中糖类抗原125

构建基于氮掺杂还原氧化石墨烯@羧基化多壁碳纳米管(N-rGO@CMWCNT)和壳聚糖@金纳米颗粒(CS@AuNP)修饰的电化学免疫传感器检测血清中糖类抗原125(CA125)。将N-rGO@CMWCNT和CS@AuNP依次修饰在玻碳电极表面,二者可通过化学作用稳定结合;再将CA125抗体孵育在电极表面,抗体与AuNP形成金硫键(Au—S),可用于检测CA125抗原,采用差分脉冲伏安法(DPV)检测不同浓度CA125所对应的电信号。扫描电子显微镜(SEM)图显示N-rGO@CMWCNT和CS@AuNP的成功合成,Raman光谱表明氮元素成功掺杂于碳纳米复合材料,线性循环伏安法(CV)曲线显示免疫传感器的成功构建。在最优实验条件下,该传感器对CA125检测线性范围为1 mU/mL~100 U/mL,检出限低至0.4 mU/mL,样品的加标回收率在94.5%~107.7%之间,同时其可在10天内保持稳定。该方法精密性好、准确度高、抗干扰能力强,可应用于肺癌患者血清中CA125的检测。

β-环糊精/还原氧化石墨烯复合电极的制备及其在氟虫腈电化学传感中的应用

先通过循环伏安法(CV)将氧化石墨烯(GO)电还原沉积在玻碳电极(GCE)上,然后通过CV将β-环糊精聚合在电还原氧化石墨烯(ErGO)之上而得到β-环糊精/还原氧化石墨烯复合电极(β-CD/ErGO/GCE),用作氟虫腈(FIP)电化学传感器。采用扫描电镜(SEM)、CV、电化学阻抗谱(EIS)和差分脉冲伏安法(DPV)对复合电极的表面形貌和电化学性能进行表征和测试。结果表明,该复合电极的修饰层厚度可控,不易脱落,稳定性好。FIP与β-CD形成超分子包合物,能有效识别FIP,传感器选择性好。FIP在0.01~20μmol/L范围内与电极响应有良好的线性关系,检出限为0.0073μmol/L,灵敏度高。该传感器在低温保存30 d后的响应电流仅下降17.5%,稳定性好,在实际水样检测中的加标回收率为96%~104%。