Showing papers on "Differential pulse voltammetry published in 1991"
TL;DR: In this article, an alizarin-modified electrode for the voltammetric determination of aluminium(III) is reported, which is simply prepared by dip-coating a high-density graphite electrode in an N,N -dimethylformamide solution of alizaran.
40 citations
TL;DR: In this paper, reversible electrochemical oxidation and reduction of PQQ were performed using a conductive polypyrrole film-coated electrode, and the electrochemical properties of entrapped pQQ are also characterized.
39 citations
TL;DR: Results from the spectroelectrochemical titration at carefully chosen wavelengths indicate that the intermediate- and low-potential couples obey simple Nernstian behavior.
Abstract: The electrochemical behavior of tetraheme cytochrome c554 from Nitrosomonas europaea has been studied by thin-layer spectroelectrochemistry, cyclic voltammetry, differential pulse voltammetry, and alternating current voltammetry. Three redox couples were detected. Midpoint potentials for the high-m intermediate-, and low-potential couples are +47, -147, and -276 mV, respectively, from the spectroelectrochemical measurements and +50, -120, and -225 mV, respectively, from the voltammetry measurements. A coulometric titration shows that two electrons are taken up by the high-potential couple and one each is taken up by the intermediate- and low-potential couples. Results from the spectroelectrochemical titration at carefully chosen wavelengths indicate that the intermediate- and low-potential couples obey simple Nernstian behavior. The electrochemical behavior of the high-potential couple is apparently not truly Nernstian but is most consistent with two sites exhibiting slight positive cooperativity. Spectral changes associated with the three couples reveal distinctive features in the reduced-minus-oxidized difference spectra. The difference spectrum of the high-potential pair of hemes suggest a mixture of a high-spin heme and a low-spin heme with maxima at 424 and 432 nm. The difference spectrum of the intermediate-potential heme is low spin with a split Soret with maxima at 414 and 424 nm. The difference spectrum of the low-potential heme also shows a split Soret with maxima at 418 and 432 nm.
32 citations
TL;DR: In this paper, a selective method based on the chemical reactivity of an immobilized modifier, 2,2-bipyridyl, toward cobalt (II) ion to yield the corresponding cation complex ((Bpy) 3 Co) 2+, which is taken up by another modifier, perfluoronated sulfonated polymer (Nafion).
Abstract: This selective method is based on the chemical reactivity of an immobilized modifier, 2,2-bipyridyl, toward cobalt (II) ion to yield the corresponding cation complex ((Bpy) 3 Co) 2+ , which is taken up by another modifier, perfluoronated sulfonated polymer (Nafion). Differential pulse voltammetry is employed, and the oxidation of the complex, at +0.1 V vs SCE, is observed. For a 5-min preconcentration period, a linear calibration curve is obtained for cobalt concentrations ranging from 7×10 −7 to 1×10 −5 mol/L, and the detection limit is 3×10 −7 mol/L
30 citations
TL;DR: Experiments performed in vitro and in vivo with amino acids, neuropeptides, or bacitracin support the view that Peak 5 is peptidergic, and peripheral administration of cysteamine and intrastriatal injection of specific somatostatin antisera both cause the eventual disappearance of Peak 5.
28 citations
TL;DR: The strong affinity of natural ionic polysaccharides for certain metal ions is exploited in the design of a new class of voltammetric sensing devices, using carbon-paste electrodes containing pectic and alginic acids for the nonelectrolytic collection and subsequent voltametric determination of copper and lead.
24 citations
TL;DR: In this paper, the use of Nafion-coated thin mercury film electrodes (NCTMFE) for determining trace amounts of Eu3+ and Yb3+ ions was examined.
24 citations
TL;DR: The experimental data obtained for this multi-redox center protein was deconvoluted in to the four redox components using theoretically generated cyclic voltammetry curves and the four mid-point reduction potentials determined.
Abstract: The direct unmediated electrochemical response of the tetrahemic cytochrome c3 isolated from sulfate reducers Desulfovibrio baculatus (DSM 1743) and D. vulgaris (strain Hildenborough), was evaluated using different electrode systems [graphite (edge cut), gold, semiconductor (InO2) and mercury)] and different electrochemical methods (cyclic voltammetry and differential pulse voltammetry). A computer program was developed for the theoretical simulation of a complete cyclic voltammetry curve, based on the method proposed by Nicholson and Shain [Nicholson, R. S. & Shain, I. (1964) Anal. Chem. 36, 706–723], using the Gauss-Legendre method for calculation of the integral equations. The experimental data obtained for this multi-redox center protein was deconvoluted in to the four redox components using theoretically generated cyclic voltammetry curves and the four mid-point reduction potentials determined. The pH dependence of the four reduction potentials was evaluated using the deconvolution method described.
21 citations
TL;DR: In this paper, the electrochemical properties of 3′-azido-3′-deoxythymidine (AZT) were investigated using cyclic voltammetry, differential-pulse voltammetric and chronocoulometry.
15 citations
TL;DR: An electrochemical method based on differential pulse voltammetry is presented for the determination of AZT in whole blood of fasted subjects, which yields a recovery of 92.30 +/- 5.92% compared to the standard solution assay.
13 citations
TL;DR: In this article, a sensitive method for the determination of Dinoseb (2-sec-butyl-4, 6-dinitrophenol) at nanomolar levels by adsorptive stripping voltammetry (AdSV) at the hanging mercury drop electrode was described.
Abstract: A sensitive method is described for the determination of Dinoseb (2-sec-butyl-4, 6-dinitrophenol) at nanomolar levels by adsorptive stripping voltammetry (AdSV) at the hanging mercury drop electrode. Cyclic voltammetry studies showed two well-defined reduction peaks, at −0.21 and −0.36 V, and demonstrated the adsorption of Dinoseb and its intermediate reduction product on the electrode. A systematic study of the experimental parameters that affect the stripping response was carried out using differential pulse voltammetry. Using a 120 second adsorption time, the limits of determination and detection were 1.5 × 10−9 and 4.6 × 10−10 M, respectively, and the relative standard deviation (n = 10) was 3.9% at a concentration level of 6.0 × 10−9 M.
TL;DR: In this article, a method for the analysis of nitrite ion and metals in a single gunshot residue sample using electrochemical methods of detection is described, in which the ion present in the sample is chemically converted to a diazonium ion, which is then detected by differential pulse voltammetry.
Abstract: A method for the analysis of nitrite ion and metals in a single gunshot residue sample using electrochemical methods of detection is described. In this method, nitrite ion present in the sample is chemically converted to a diazonium ion, which is then detected by differential pulse voltammetry. The peak current for the reduction of the diazonium ion is proportional to the nitrite concentration up to 400 ppb nitrite (r = 0.9995), with an absolute detection limit of 0.01 μg nitrite. Lead ion present in the gunshot residue sample is detected in the same voltammetric scan, and antimony is subsequently detected by anodic stripping voltammetry. The method has been successfully applied to a number of samples obtained in test firings.
TL;DR: A voltammetric method based on the adsorption of tin(IV)-catechol complex on a hanging mercury drop electrode is described for the determination of ultra-trace amounts of tin in environmental samples as discussed by the authors.
Abstract: A voltammetric method based on the adsorption of tin(IV)-catechol complex on a hanging mercury drop electrode is described for the determination of ultra-trace amounts of tin in environmental samples. The interfacial accumulation of the analyte and the use of differential pulse voltammetry during the reduction step provide substantial gains in the sensitivity and permit selective determination of tin in the presence of other elements. Optimal conditions for this method are pH 4.2, 1×10-4M catechol, and accumulation with stirring at 0.0V versus Ag/AgCl. The detection limit based on the use of the tin peak which occurred at -0.3V versus Ag/AgCl was 5ng/L for an accumulation period of 180s and the relative standard deviation at 50ng/L was 2.2%. The successful application of the method to tin determination in water and sediment samples is reported.
TL;DR: In this paper, the behavior of oxazepam in adsorptive stripping voltammetry was studied taking into account those conditions which have an influence on the accumulation step (electrolyte, pH, time, potential, drop size and stirring rate), rest time and stripping step.
01 Jan 1991
TL;DR: In this paper, three classes of voltammetric methods are reviewed: steady-state voltammetry, potential step voltameters, and linear sweep voltametermetry.
Abstract: Three classes of voltammetric methods are reviewed: steady-state voltammetry, potential step voltammetry and linear sweep voltammetry. In the first class are included rotating disk electrode voltammetry and polarography. Normal pulse voltammetry, reverse pulse voltammetry and differential pulse voltammetry are included in the second category. The emphasis of the review is directed to the implementation of the techniques with electrodes of conventional size but the effect of spherical diffusion is introduced to portend the discussion of the methods as used with microelectrodes.
TL;DR: In this paper, the electrochemical reduction of benzil to benzoin, was studied in strongly acid and alkaline media, at DME, and convolution potential step voltammetry (CPSV) was applied to determine kinetic constants corresponding to the ketolization reaction undergone by the stilbenediol.
TL;DR: Differential pulse voltammetry at the hanging mercury drop electrode was used to determine the reduction potentials, E 1 2, of the aromatic structures containing a basic nitrogen substituent in the asphaltene fractions of coal derived liquids as mentioned in this paper.
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TL;DR: This chapter presents an overview of in vivo voltammetry technique, a technique allowing repetitive measurements of transmitter release/metabolism to be made in vivo without the need to extract samples or sacrifice the animal.
Abstract: Publisher Summary This chapter presents an overview of in vivo voltammetry technique. Voltammetry is a means of measuring the concentration of compounds based on their redox characteristics. In voltammetry, electrons are added to or removed from compounds by electric fields. This field is generated by application of voltage across an electrode/solution interface. At a critical voltage—dependent on the compound, electrode, and electrolyte—the chemical present at the electrode surface surrenders its electrons to the electrode, resulting in a small flow of current. If the polarity of the field is reversed, the electrons can be returned from the electrode to the oxidized compound, reverting it to its original state. In vivo voltammetry is a technique allowing repetitive measurements of transmitter release/metabolism to be made in vivo without the need to extract samples or sacrifice the animal. The high spatial and temporal resolution of the methodology allow data to be obtained in tiny nuclei or subregions. Fast cyclic voltammetry, and differential pulse voltammetry, are complementary techniques, both using carbon fiber microelectrodes and generating information about related aspects of neuronal function.
TL;DR: In this article, the potentials of the four oxidation-reduction states were calculated by simulations using two models and compared with corresponding values from the mediated spectropotentiometric titration.
TL;DR: In this article, a carbon-paste electrode containing octadecylamine was used for voltammetric determination of pyridoxal in aqueous solutions, and a linear calibration curve was obtained in a concentration range of 1×10-5 -to 2×10 -4M.
Abstract: A carbon-paste electrode containing octadecylamine was used for voltammetric determination of pyridoxal in aqueous solutions. After chemical deposition of pyridoxal on the modified electrode through Schiff base formation, differential pulse voltammetry exhibited a well-developed reduction wave at +0.52V vs. Ag/AgCl, due to the electrooxidation product of the Schiff base or pyridoxal which was regenerated by hydrolysis. No reduction wave was detected for compounds bearing a formyl group except for salicylaldehyde, which showed an analogous reduction wave at a potential of +0.80V. This fact suggests that the electrode can be used for selective determination of pyridoxal. A linear calibration curve was obtained in a concentration range of 1×10-5 -to 2×10-4M.
TL;DR: In this paper, the results obtained by differential pulse voltammetry allowed the development of a method for the determination of this antiseptic in the ranges 8.0×10−7 − 10.0 × 10−7, 1.0x10−6 − 10 × 10 − 6, and 1. 0×10 −5 − 7.0 x 10−5 mol l−1, using ΔE=50 mV.
Abstract: An electroanalytical study of the 4-chloro-3-methylphenol oxidation process at a glassy carbon electrode in aqueous solution has been carried out using different voltammetric techniques. The results obtained by differential pulse voltammetry allowed the development of a method for the determination of this antiseptic in the ranges 8.0×10−7 – 10.0×10−7, 1.0×10−6 – 10.0×10−6 and 1.0×10−5 – 7.0×10−5 mol l−1, using ΔE=50 mV. The coefficient of variation is 2.3% for a concentration of 5.0×10−6 mol l−1, with a limit of detection of 2.0×10−7 mol l−1. Good results were obtained by applying the proposed differential pulse voltammetric method to the determination of 4-chloro-3-methylphenol in pharmaceutical and cosmetric samples initially containing or spiked with this compound.
TL;DR: In this article, a fast scan differential pulse voltammetry at a hanging mercury drop electrode was used to determine 4-nitrobiphenyl in the concentration range (2 − 10). 10 -9 mol l -1 with five-minute accumulation in stirred solution, with the advantage of a smoother baseline and smaller interference from substances that yield only tensametric peaks.
Abstract: Optimum conditions were found for the determination of 4-nitrobiphenyl by fast scan differential pulse voltammetry at a hanging mercury drop electrode in the concentration range 1 . 10 -5 to 2 . 10 -7 mol l -1 . A further increase in sensitivity was attained by adsorptive accumulation of this substance on the surface of the working electrode, permitting determination in the concentration range (2 – 10) . 10 -8 mol l -1 with one minute accumulation of the substance in unstirred solution or (2 – 10) . 10 -9 mol l -1 with three-minute accumulation in stirred solution. Linear scan voltammetry can be used to determine 4-nitrobiphenyl in the concentration range (2 – 10) . 10 -9 mol l -1 with five-minute accumulation in stirred solution, with the advantage of a smoother baseline and smaller interference from substances that yield only tensametric peaks.
TL;DR: In this article, differential pulse polarography at various pH values at 25, 37, and 50°C was used to study the thienodiazepine Clotiazepam in an alkaline medium, with two well-defined polarographic peaks attributed to the azomethine group and the carboxylic group of the hydrolysis product.
Abstract: The hydrolysis reaction in an alkaline medium of the thiendodiazepine Clotiazepam has been studied by differential pulse polarography at various pH values at 25, 37, and 50°C. In an alkaline medium, Clotiazepam exhibits two well-defined polarographic peaks, attributed to the azomethine group of the parent compound and the carboxylic group of the hydrolysis product, with a potential difference of 0.160 V, practically constant in the pH range studied. Kinetic studies of the reversible hydrolysis process based on the current changes with time of the first polarographic peak in indicate that the process is a pseudo-first-order reaction with a rate constant dependent on hydroxide ion concentration. Arrhenius parameters were also calculated. A voltammetric study of the hydrolysis product has been carried out, and determination methods have been developed by differential pulse voltammetry and differential pulse polarography.
TL;DR: Polarographic reduction of the genotoxic N,N’-dinitrosopiperazine was studied and its mechanism was suggested in this paper, where the optimum conditions were established for the determination of this substance by tast polarography over the concentration region of 1. 10 -3 to 1. 10 -6 mol l -1 and by differential pulse polarography on the conventional dropping mercury electrode or by fast scan differential pulse voltammetry and linear sweep voltammetric on a hanging mercury drop electrode over a
Abstract: Polarographic reduction of the genotoxic N,N’-dinitrosopiperazine was studied and its mechanism was suggested. Optimum conditions were established for the determination of this substance by tast polarography over the concentration region of 1 . 10 -3 to 1 . 10 -6 mol l -1 and by differential pulse polarography on the conventional dropping mercury electrode or by fast scan differential pulse voltammetry and linear sweep voltammetry on a hanging mercury drop electrode over the concentration region of 1 . 10 -3 to 1 . 10 -7 mol l -1 . Attempts at increasing further the sensitivity via adsorptive accumulation of the analyte on the surface of the hanging mercury drop failed. The methods are applicable to the testing of the chemical efficiency of destruction of the title chemical carcinogen based on its oxidation with potassium permanganate in acid solution.
TL;DR: In this paper, a fast scan differential pulse voltammetry at a hanging mercury drop electrode in the concentration range 1 10 -5 -2 10 -7 mol l -1 was used for the determination of N-nitroso-N-methyl aniline and its derivatives substituted in the 4 position by -CH 3, OCH 3, Cl, -CN, -OH or -NO 2 groups.
Abstract: Optimum conditions were found for the determination of N-nitroso-N-methyl aniline and its derivatives substituted in the 4 position by -CH 3 , -OCH 3 , -Cl, -CN, -OH or -NO 2 groups by fast scan differential pulse voltammetry at a hanging mercury drop electrode in the concentration range 1 10 -5 -2 10 -7 mol l -1 . It was demonstrated that these techniques are useful for the analysis of a mixture of the test substances either directly or after separation by thin-layer chromatography and that false positive results can be eliminated by UV irradiation of the test sample. An attempt to further increase the sensitivity by adsorptive accumulation of the test substances on the surface of the hanging mercury drop electrode was not successful as the test N-nitroso compounds are practically not adsorbed on this electrode.
TL;DR: Evidence was obtained that peptides alter the recording properties of the microelectrodes when present at sufficient concentrations and such an effect may explain the result obtained in vivo.