Showing papers on "Polarography published in 1990"
TL;DR: In this paper, the electrocatalytic reduction of CO 2 on mercury with Ni(II)-cyclam was studied in detail by cyclic voltammetry, polarography and electrocapillarity of aqueous solutions with and without the catalyst under N 2, CO and CO 2.
87 citations
73 citations
TL;DR: In this article, the influence of the pH, reactant concentration and drop time on the different polarographic and kinetic parameters in the two electroreduction processes involved is studied, and experimental DP curves and the theoretical profiles corresponding to different mechanisms are compared.
35 citations
TL;DR: In this paper, the rate of reaction for a given supporting electrolyte was always slower in dimethylsulfoxide, a result which was attributed to the stronger solvating ability of this solvent for cations.
34 citations
TL;DR: In this paper, the complex formation of Zn(II) and Cd(II), with polymethacrylic acid (PMA), was studied by sampled direct-current, normalpulse and reverse-pulse polarography.
33 citations
TL;DR: In this paper, the use of a glassy carbon electrode coated with a Nafion perfluorosulphonate resin containing N,N′-bis(3-carboxysalicylidene)trimethylenediamine (a Schiff base) in anodic stripping voltammetry for the determination of trace amounts of mercury is described.
Abstract: The use of a glassy carbon electrode coated with a Nafion perfluorosulphonate resin containing N,N′-bis(3-carboxysalicylidene)trimethylenediamine (a Schiff base) in anodic stripping voltammetry for the determination of trace amounts of mercury is described. The coating procedure, performed by applying a solution of the polymer containing the Schiff base to the electrode surface, is convenient and fast. In comparison with the glassy carbon electrode, the main advantages of the modified electrode are improved resistance to interference from surface-active compounds and increased sensitivity and selectivity. The utility of the modified electrode was demonstrated by its application to samples of urine and natural water.
30 citations
TL;DR: In this article, a simple and rapid method for the determination of the antibiotic ciprofloxacin by differential pulse polarography (DPP) has been developed, and the changes in the voltammetric behavior of this drug compound with pH was studied.
Abstract: A simple and rapid method for the determination of the antibiotic ciprofloxacin by differential pulse polarography (DPP) has been developed. The changes in the voltammetric behavior of this drug compound with pH was studied, and the most suitable pH for analytical purposes was found to be pH 8.5. The DPP behavior of this compound at this pH exhibited two reduction waves at −1.44 and −1.64 V. The former wave could be used to determine ciprofloxacin between 5 × 10−7 and 3 × 10−5 M. The method was applied to the determination of ciprofloxacin in formulated tablets with a relative standard deviation of less than 0.4%.
30 citations
TL;DR: In this paper, a 25-μm diameter microelectrode is constructed from 80% platinum-20% iridium alloy, and steadystate reduction currents and sharp oxidation peaks are obtained for the determination of cadmium at the PtIr-based mercury film electrode.
29 citations
TL;DR: A single-sweep polarographic determination of nitrite in 0.2 M sulphuric acid medium containing nickel(II) sulphate and ammonium thiocyanate is described in this article.
28 citations
TL;DR: In this paper, the behavior of the complex of copper with 1,10-phenanthroline at a mercury electrode was investigated in acidic chloride media, and the effects of various operational parameters (pH, ligand concentration, potential and accumulation time) on the reduction current of the adsorbed chelate were discussed.
22 citations
TL;DR: Polarography based on the Clark oxygen electrode seems to be an easy, rapid, and sensitive technique for studying enzyme reactions consuming or evolving O2 in apolar media.
TL;DR: In this article, a single-sweep polarographic wave was used for the determination of trace amounts of nitrite in an acidic medium (pH 2) containing cobalt(II), thiocyanate and ascorbic acid.
TL;DR: Anodic waves of methimazole (I) (1-methylimidazole-2-thiol) and carbimazoles (II) on mercury electrodes correspond to mercury salt formation as mentioned in this paper.
Abstract: Anodic waves of methimazole (I) (1-methylimidazole-2-thiol) and carbimazole (II) (1-ethoxycarbonyl-3-methyl-2-thio-4-imidazoline) on mercury electrodes correspond to mercury salt formation. Both compounds form in the thiono form a soluble complex at pH < 6, compound (I) at higher pH-values a slightly soluble salt of the thiol form. Electrode processes involving the thiol form are complicated by adsorption. Oxidation at solid electrodes occurs only at potentials more than 0.5 V more positive. For compound (I) spectrophotometry indicated pKa=12.0 ± 0.2. By d.c. polarography in 0.1 M H2SO4 containing 10% ethanol the determination of both compounds is possible between 4 × 10− and 1 × 10−3 M, by differential pulse polarography between 1 × 10− and 1 × 10−4 M, by differential pulse voltammetry at HMDE between 5 × l0−7 and 6 × 10− M.
TL;DR: Advantages of this technique compared with the use of polarography, differential pulse polarography and pH titrations are discussed, with the complexes formed by cadmium with glycine, alanine, valine and aspartic acid as examples.
TL;DR: In this article, the linearity ranges for bismuth and lead are 7 × 10 −8 −1 × 10−5 and 1 × 10 -7 −6 × 10-6M, respectively.
Abstract: Bismuth(III) and lead(II) can be reduced at –0.65 V (versus SCE) and –0.76 V (versus SCE), respectively, in a sodium hydroxide solution containing glyoxalbis(2-hydroxyanil)(GBHA)[2,2′-(ethanediylidenedinitrilo)diphenol] by using single-sweep polarography, based on their adsorptive GBHA complexes. Both waves are sensitive and selective and can be utilised for the simultaneous determination of these two elements. The linearity ranges for bismuth and lead are 7 × 10–8–1 × 10–5 and 1 × 10–7–6 × 10–6M, respectively. The sensitivity for bismuth can be increased ten-fold by using cathodic stripping voltammetry with a static mercury electrode. The proposed procedure was applied to the simultaneous determination of bismuth and lead in some ore and alloy samples. The mechanism of the electrode process has also been studied.
TL;DR: In this article, a highly sensitive differential-pulse polarographic method was developed for the determination of sub-micromolar concentrations of nitrite ion after diazotisation with sulphanilic acid at low pH and coupling with N-(1-naphthyl)ethylenediamine dihydrochloride.
Abstract: A highly sensitive differential-pulse polarographic method has been developed for the determination of sub-micromolar concentrations of nitrite ion after diazotisation with sulphanilic acid at low pH and coupling with N-(1-naphthyl)ethylenediamine dihydrochloride. At pH 2.0 and with 0.01 M potassium dihydrogen phosphate as the base electrolyte, the peak current at +0.020 V versus a saturated calomel electrode increases linearly in the concentration range 5 × 10–8–2.12 × 10–6M in simple aqueous solutions. The relative standard deviation is 3.3% for the determination of 1 × 10–7M nitrite.
TL;DR: Nicotinamide N 1 -oxide was studied by dc and DP polarography and voltammetry from strongly acidic solutions (5 M H 2 SO 4 ) to solutions of pH 12 as mentioned in this paper.
TL;DR: In this paper, the polarographic behavior of the pesticide Diazinon was investigated in water/methanol solutions and two methods were proposed for its determination: differential pulse polarography with a detection limit of 2.65 × 10−6 M, and the second is based on adsorptive stripping voltammetry at a hanging mercury drop electrode that yields a detection range of 4.01 × 10 −9 M.
Abstract: The polarographic behavior of the pesticide Diazinon was investigated in water/methanol solutions. Two methods are proposed for its determination. The first involves differential pulse polarography with a detection limit of 2.65 × 10−6 M, and the second is based on adsorptive stripping voltammetry at a hanging mercury drop electrode that yields a detection limit of 4.01 × 10−9 M.
TL;DR: In this article, a mechanism for the electrochemical reduction of tetrazolium blue (TB2+ ) on the surface of a dropping mercury electrode was proposed, which was performed in a heterogeneous solvent: non-ionic micelles of Triton X-100, in an aqueous buffer solution.
TL;DR: In this paper, a convolution method is described that converts current-voltage curves obtained at spherical mercury electrodes into the classical wave shape that is familiar from polarography, and the wave shape is then converted to the polar wave shape.
Abstract: Linear-scan staircase voltammetry and cyclic staircase voltammetry generate unsatisfactory current-voltage curves even for reversible electrode processes. A convolution method is described that converts such curves, obtained at spherical mercury electrodes, into the classical wave shape that is familiar from polarography
TL;DR: The transfer of I−, BF4−4, ClO−4 and RSO−3 was investigated at the aqueous/nitrobenzene or 1,2-dichloroethane interface in the temperature range from 4 to 80°C.
TL;DR: In this paper, the a.c. polarographic behavior of methotrexate (MTX) was studied and the nature of the process taking place at the dropping mercury electrode was elucidated.
TL;DR: In this paper, the electroreduction of p-nitrosodiphenylamine (p-NDPA) in an alkaline aqueous solution containing cetyltrimethylammonium bromide (CTAB) as a cationic surfactant was investigated by polarography, cyclic and rotating disc voltammetry.
TL;DR: In this article, le dosage est base sur l'accumulation du complexe germanium (IV)-diol par adsorption sur une electrode goutte de mercure.
Abstract: Le dosage est base sur l'accumulation du complexe germanium (IV)-diol par adsorption sur une electrode goutte de mercure, suivie de l'analyse voltammetrique. Les diols utilises sont le catechol ou le pyrogallol; dans ce derniers cas, la limite de detection est de 0,1 ng/ml
TL;DR: In this article, a well-defined cathodic wave was produced over the entire pH range 5-10, and the wave was characterized as being diffusion-controlled, although adsorption phenomena played a limited role in the reduction process.
TL;DR: In the presence of polyethylene glycol monostearate (PEGMS), the reduction potentials for In(III) and Cd(II) become well separated in 0.1 mol dm −3 potassium chloride medium.
TL;DR: In this paper, an electrode process mechanism is proposed in which the formation of a catalytic complex between aquo-nickel and veronalate-Nickel (II) on the one hand and unprotonated pilocarpine adsorbed on the electrode surface on the other is followed by the reduction of nickel(II) in the complex and the release of the catalytic ligand.
TL;DR: Ceftriaxone is a member of the "third generation" of cephalosporin antibiotics which adsorbs strongly onto a mercury electrode and by accumulating this compound at a static mercury dropping electrode prior to differential pulse voltammetric measurements, very high sensitivities can be readily achieved.
TL;DR: The electrochemical behavior of zinc(II) dithiocarbamate complexes (Zn(RRdtc) 2 ) has been investigated at both platinum and mercury electrodes and compared with that of the analogous cadmium complexes as mentioned in this paper.
Abstract: The electrochemical behavior of zinc(II) dithiocarbamate complexes (Zn(RR'dtc) 2 ) has been investigated at both platinum and mercury electrodes and compared with that of the analogous cadmium complexes (Cd(RR'dtc) 2 ) Reduction processes for Zn(RR'dtc) 2 are less affected by the choice of electrode material than are the oxidation processes At both platinum and mercury electrodes, the major reduction process occurs at very negative potentials and yields elemental zinc or zinc amalgam, respectively, and free dithiocarbamate
TL;DR: Using a static mercury drop electrode, a current vs potential scan was performed between −0.7 and −1.10 vs an Ag/AgCl reference electrode as mentioned in this paper, and the reduction potential for diacetyl was − 0.83 V.
Abstract: Reconstituted single strength orange juice was distilled to recover diacetyl. 0.5 mL of 1N LiOH was added to 4.5 mL of distillate. Using a static mercury drop electrode, a current vs potential scan was performed between −0.7 and −1.10 vs an Ag/AgCl reference electrode. The reduction potential for diacetyl was −0.83 V. Peak heights were proportional to concentration throughout the test range (8.3 ppb to 1 ppm). Diacetyl recoveries were approximately 85%.