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.

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.

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.

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.

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, 1 M Ag-AgCl electrode with large area as reference electrode, 0.2 M NH4AC as supporting electrolyte and pH buffer solution, pulse amplitude (AE) of 25 mV, scan rate at 2 mV·S-1and scan potential ranging 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.

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%.

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,

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).

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。

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。

Simultaneous determination of three 5-nitroimidazoles in foodstuffs by differential pulse voltammetry and chemometrics

The voltammetric behaviour of three 5-nitroimidazoles,metronidazole,tinidazole and ornidazole,was investigated,and a method was developed for the simultaneous determination of these compounds,based on their reduction at a hanging mercury drop electrode（HMDE） in pH 8.95 buffer with differential pulse voltammetric（DPV） approach.Well defined voltammetric waves with peak potentials of -692,-640 and -652 mV were observed for these compounds,respectively.It is difficult to determine them individually from their mixtures without preseparation,for their voltammetric peaks overlapped seriously,so the chemometrics were used to resolve the overlapped voltammogram and quantify the mixtures.The proposed method was successfully applied to the determination of three 5-nitroimidazoles in milk and honey samples.

Application of differential pulse stripping voltammetry and chemometrics for the determination of three antibiotic drugs in food samples

A reliable method for simultaneous determination of three antibiotic drugs（levofloxacin,gatifloxacin and lomefloxacin） by differential pulse stripping voltammetry（DPSV） in Britton-Robinson buffer（pH 7.96） was presented.The method is based on adsorptive accumulation of the antibacterial drugs on a hanging mercury dropping electrode（HMDE）,followed by the reduction of the adsorptive species by the technique of DPSV.Optimal conditions,the deposition time of 80 s,the deposition potential of—1250 mV,and the scan rate of 25 mV/s,were obtained.The linear concentration ranges of 0.010-0.080μg/mL were obtained for all these three antibiotic drugs,while the detection limits were 2.38,3.20 and 1.60ng/mL for levofloxacin,gatifloxacin and lomefloxacin,respectively.In this work,chemometrics methods,such as classical least squares（CLS）,partial least squares（PLS）, principle component regression（PCR） and radial basis function-artificial neural networks（RBF-ANN）,were used to quantitatively resolve the overlapping signals.It was found that PCR gave the best results with total relative prediction error（RPE_T） of 7.71%.The proposed method was applied to determine these three drugs in several commercial food samples with spiked method and yielded satisfactory recoveries.

Determination of trace Pb(II), Cd(II) and Zn(II) using differential pulse stripping voltammetry without Hg modification

In this work,we reported a simultaneous determination approach for Pb(II),Cd(II)and Zn(II)atμg L 1concentration levels using differential pulse stripping voltammetry on a bismuth film electrode(BiFE).The BiFE could be prepared in situ when the sample solution contained a suitable amount of Bi(NO)3,and its analytical performance was evaluated for the simultaneous determination of Pb(II),Cd(II)and Zn(II)in solutions.The determination limits were found to be 0.19μg L 1for Zn(II),and0.28μg L 1for Pb(II)and Cd(II),with a preconcentration time of 300 s.The BiFE approach was successfully applied to determine Pb(II),Cd(II)and Zn(II)in tea leaf and infusion samples,and the results were in agreement with those obtained using an atomic absorption spectrometry approach.Without Hg usage,the in situ preparation for BiFE supplied a green and acceptability sensitive method for the determination of the heavy metal ions.

Automated Determination of Cd^(2+) and Pb^(2+) in Natural Waters with Sequential Injection Analysis Device Using Differential Pulse Anodic Stripping Voltammetry

An electrochemical flow device has been developed for the determination of heavy metal ions(HMI)in water using multiwalled carbon nanotubes(MWCNTs)/Nafion(NA)/Hg electrode,by mean of diff erential pulse anodic stripping voltammetry coupled with sequential injection analysis.The accuracy of the determination was ensured by the great electrical conductivity of MWCNTs and the high adsorption capacity of Hg.NA was used for MWCNTs immobilization for the long-term application of the electrode.The mercury film was cleaned after determination and another one would form during deposition.A lower limit of detection and a wider determination range of Cd^(2+)and Pb^(2+)could be achieved using the automatically analytical device combining with the MWCNTs/NA/Hg-modified electrode.The real-time monitoring of Cd^(2+)and Pb^(2+)in fresh water using this device continued for 10 days.The results indicated that the method was potential for on-site and real-time determination of HMI in water samples.

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。

稀土基金属有机框架材料的制备及其对Pb^(2+)的电化学检测

室温下以硝酸钬为金属源,均苯三甲酸为有机配体,通过--步共混法制备出形貌均一的棒状稀土基金属有机框架材料(Ho-MOF),在玻碳电极基底上,采用两步滴涂法制备Ho-MOF-NIP复合修饰电极,成功构建了用于检测Pb^(2+)的电化学传感器(Ho-MOF-NIP/GCE)。采用差分脉冲阳极溶出伏安法(DPASV)研究了Pb^(2+)在该修饰电极上的电化学行为。实验结果表明:该电极对Pb2的检测灵敏度显著提升,在0.1~1 mmol.LI范围内,氧化峰电流值与Pb^(2+)的浓度呈现良好的线性关系,检测限为7 pumol.L'(S/N=3),该方法可用于水样中Pb^(2+)的快速检测。

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。

基于玉米秸秆和荔枝树枝生物炭的电化学传感器对水中镉离子的检测

以玉米秸秆和荔枝树枝为原料,500℃下制备生物炭。采用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和傅里叶变换红外(FTIR)光谱仪对两种生物炭进行表征。通过滴涂法将两种生物炭材料分别修饰在玻碳电极(GCE)表面,成功构建了Y-BC/GCE和L-BC/GCE电化学传感器,并在醋酸盐缓冲液中用微分脉冲伏安法(DPV)研究了镉金属离子(Cd^(2+))在不同电极上的电化学行为。结果表明,两种生物炭修饰电极对Cd^(2+)的检测都取得较好的效果。在最优条件下(Y-BC/GCE:沉积电位-1.6 V、沉积时间100 s、pH=4;L-BC/GCE:沉积电位-1.3 V、沉积时间100 s、pH=5),两种生物炭传感器在浓度范围为0.2~20μmol/L内都有良好的线性关系,Cd^(2+)检出限分别低至0.06和0.05μmol/L。同时这两种生物炭传感器具有良好的稳定性、重复性以及抗干扰性,对实际样品中的Cd^(2+)具有良好的回收率(Y-BC/GCE:96.97%~102.57%;L-BC/GCE:97.01%~99.10%)。

光催化降解苯酚污染物的电化学监测——推荐一个分析化学综合实验

针对目前高校开展的分析化学实验教学内容单一,侧重常规分析方法以及仪器基本原理介绍等问题,将综合性实验教学项目引入到教学中,能够增强学生独立探索、主动思考和分析问题的能力。本文设计了基于纳米TiO2光催化剂催化降解苯酚的综合性实验方案,涉及光催化降解和电化学监测的原理,以及光催化降解和电化学装置的搭建等。