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 betwee...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.展开更多
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 ...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.展开更多
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 o...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.展开更多
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 pr...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.展开更多
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 pro...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.展开更多
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 wo...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.展开更多
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,accumula...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%.展开更多
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 o...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.展开更多
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_...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).展开更多
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)...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.展开更多
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 ...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,展开更多
Even in small concentrations,toxic metals like lead,cadmium,and mercury are dangerous to the environment and human health.Environmental monitoring depends on precisely identifying these heavy metals,particularly cadmi...Even in small concentrations,toxic metals like lead,cadmium,and mercury are dangerous to the environment and human health.Environmental monitoring depends on precisely identifying these heavy metals,particularly cadmium ions(Cd(Ⅱ)).In this study,we present a novel screen-printed carbon electrode(SPCE)modified with single crystallineα-Fe_(2)O_(3)nano-hexagons that functions as a sensor for detecting Cd(Ⅱ).The performance of the fabricated sensor was thoroughly assessed and compared with unmodified SPCE using the voltammetric method.The crystalline structure of the synthesizedα-Fe_(2)O_(3)nano-hexagons was confirmed through XRD,and surface analysis revealed an average diameter and thickness of 86 nm and 9 nm,respectively.Theα-Fe_(2)O_(3)modified SPCE yields a 7-fold enhanced response(at pH 5.0 vs.Ag/AgCl)to Cd(Ⅱ)than bare SPCE.The modified electrode effectively detects Cd(Ⅱ)with a linear response range of up to 333.0μmol/L and a detection limit of 0.65 nmol/L under ideal circumstances.This newly fabricated sensor offers significant potential for environmental monitoring applications by providing outstanding practicality,anti-interference ability,and repeatability for detecting Cd(Ⅱ)in water samples.展开更多
基金This study is financially supported by the National Natural Science Foundation of China (No. 60508012)the Natural Sci-ence Foundation of Zhejiang Province (No. Y106725)+1 种基金the Natural Science Foundation of Ningbo (No. 2006A610048)the Scientific and Technological Project Funding of Zhejiang Province (No. 2006C31040).
文摘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.
文摘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.
文摘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.
基金support by the National Natural Science Foundation of China (No21065007)the State Key Laboratory of Food Science and Technology of Nanchang University(SKLF-MB-201002 and SKLF-TS-200919)
文摘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.
基金the National Natural Science Foundation of China(No.2 0 0 75 0 13) and China Postdoctoral Science Foun-dation(No.2 0 0 30 33492 )
文摘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.
文摘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.
文摘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%.
文摘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.
文摘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).
文摘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.
文摘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,
文摘Even in small concentrations,toxic metals like lead,cadmium,and mercury are dangerous to the environment and human health.Environmental monitoring depends on precisely identifying these heavy metals,particularly cadmium ions(Cd(Ⅱ)).In this study,we present a novel screen-printed carbon electrode(SPCE)modified with single crystallineα-Fe_(2)O_(3)nano-hexagons that functions as a sensor for detecting Cd(Ⅱ).The performance of the fabricated sensor was thoroughly assessed and compared with unmodified SPCE using the voltammetric method.The crystalline structure of the synthesizedα-Fe_(2)O_(3)nano-hexagons was confirmed through XRD,and surface analysis revealed an average diameter and thickness of 86 nm and 9 nm,respectively.Theα-Fe_(2)O_(3)modified SPCE yields a 7-fold enhanced response(at pH 5.0 vs.Ag/AgCl)to Cd(Ⅱ)than bare SPCE.The modified electrode effectively detects Cd(Ⅱ)with a linear response range of up to 333.0μmol/L and a detection limit of 0.65 nmol/L under ideal circumstances.This newly fabricated sensor offers significant potential for environmental monitoring applications by providing outstanding practicality,anti-interference ability,and repeatability for detecting Cd(Ⅱ)in water samples.
