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  • Polymer and Materials Science  (13)
  • Finite diffusion space  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Application of partial least-squares regression for signal resolution in differential pulse anodic stripping voltammetry of thallium and lead (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 309-312 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This work addresses the problem of signal resolution by partial least-squares regression (PLS) for differential pulse stripping voltammograms. The performance of PLS is demonstrated for an example of calibration with mixtures of two analytes (Tl+ and Pb2+) with strongly overlapping voltammograms. The accuracy of the determination of concentrations for validation mixtures was found to be considerably higher with PLS than with simple evaluation using currents observed at two potentials (requiring resolution of a system of two linear equations with two unknowns). Hence, PLS is recommended for computer-assisted, on-line voltammetric analysis of multicomponent systems.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140020408
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  • 2
    Digitale Medien
    Digitale Medien
    Optimization of parameters for differential pulse voltammetry at the hanging mercury drop electrode (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 437-440 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The detection limit of differential pulse voltammetry at a hanging mercury drop electrode is investigated. The most important result of this study is that very small pulse amplitudes considerably improve the signal-to-background ratio and lead to lower detection limits. Due to the fact that (in practice) the background current does not originate only from capacitive properties of the electrode, an optimal pulse duration also exists, which guarantees the highest signal-to-background ratio. It is shown that the background current consists of the capacitive current and a very noisy but, on average, constant component, presumably of a faradaic nature that originates from impurities. The effects of the prepulse time, the pulse amplitude, the pulse duration, the step height of the staircase ramp, and the duration of the current sampling time on the signal and background intensity and noise are described.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140010510
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  • 3
    Digitale Medien
    Digitale Medien
    Development of analytical procedures based on abrasive stripping coulometry and voltammetry for solid state phase microanalysis of natural and synthetic tin-, arsenic-, and antimony-bearing sulfosalts and sulfides of thallium, tin, lead, and silver (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 319-328 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Solid state electroanalysis ; Microanalysis ; Voltammetry ; Coulometry ; Minerals ; Sulfides ; Sulfosalts ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Analytical procedures are described for the solid state phase microanalysis of synthetic and natural tin-, arsenic-, and antimony-bearing sulfosalts and sulfides of thallium, tin, lead, and silver. In these procedures, abrasive stripping voltammetry and coulometry of the solid phases are applied. Trace amounts of the sample compounds were transferred onto the surface of a graphite electrode and the electrochemical reduction or oxidation was followed by voltammetric techniques. The most valuable technique for distinguishing different mineral phases is to record the anodic dissolution voltammograms after a preliminary electrolytic reduction of the sulfides or sulfosalts to the elementary metals which are still confined to the electrode surface. For various compounds an approach was developed in which the ratio of charges consumed during reduction and oxidation of the solid phases is used for unambiguous identification. Coulometric measurements are also used for the determination of the quantitative composition of the solid phases.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140070404
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  • 4
    Digitale Medien
    Digitale Medien
    Abrasive stripping voltammetric analysis of tin - bismuth (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 85-87 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The analysis of tin-bismuth alloys using a new stripping technique, abrasive stripping voltammetry, is described. Small amounts of the alloy are transferred by mechanical abrasion from the solid alloy onto the surface of a paraffin-impregnated graphite electrode. These traces are anodically stripped off with differential pulse voltammetry. The ratio of the tin and bismuth peak currents provide a measure of their relative content in the alloy. The determinations have standard deviations of about 5%. Peak potentials are reproducible within a 20-mV range.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140020116
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  • 5
    Digitale Medien
    Digitale Medien
    The standard potentials of the electrode “dissolved atomic mercury/dissolved mercury ions” (1996)
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 1075-1076 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Standard potentials ; Redox electrode ; Mercury ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The standard potentials of the redox electrodes “dissolved atomic mercury/dissolved mercury ions” are calculated to be E0(Hg0/Hg2+) = 0.661 V (vs. SHE and E0/Hg0 Hg22+) = 0.410V (vs. SHE). The standard potential of the electrode “metallic mercury/dissolved mercury ions” E0(Hg/Hg2+) = 0.8535V (vs. SHE) is the formal potential of the electrode “dissolved atomic mercury/dissolved mercury ions” at saturation activity of atomic mercury. In all calculations involving dissolved atomic mercury below saturation activity, the standard potentials E0(Hg0/Hg2+) and E0(Hg0/Hg22+) have to be used or the relation between them and E0(Hg/Hg2+) and E0(Hg/Hg22+) has to be taken into account.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140081118
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  • 6
    Digitale Medien
    Digitale Medien
    What makes the anodic stripping voltammetry of mercury at a trace level possible? (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 1189-1196 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Mercury ; Analysis ; Adsorptive accumulation ; Anodic stripping voltammetry ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For thermodynamic reasons it is impossible to describe the anodic stripping voltammetry (ASV) of mercury at concentrations below 10-7 mol/L as involving a simple deposition and dissolution of metallic mercury. That follows from the finite solubility of elemental mercury in water at ambient temperature. Instead, it is a more or less strong adsorption of mercury atoms on the electrode surface which makes ASV possible. At these low concentrations, the atomic mercury in the solution can no longer be neglected. A theoretical description for staircase cyclic voltammetry of the reaction Hgads0 ⇌ Hgnq0 ⇌ Hgaq2+ + 2e- has been developed and it is discussed with respect to the ASV of mercury. The adsorption of atomic mercury is considered for the case of different electrode materials and adsorption constants have been estimated from underpotential deposition peaks. The distribution of the following mercury species is given for different electrode potentials and total mercury concentrations: Hg22+, Hg2+, Hgaq0, Hgads0 and Hgmet0.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140091513
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  • 7
    Digitale Medien
    Digitale Medien
    Electrochemistry and analytical application of the tin(IV) complex of N-benzoyl-N-phenylhydroxamic acid in 2-propanol solution (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 230-236 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Tin ; N-Benzoyl-N-phenyl-hydroxamic acid ; Mechanism ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The tin(IV) complex of N-benzoyl-N-phenyl-hydroxamic acid (HX) and chloride ions [SnIVX2Cl2]0 is reduced in 2-propanol solution via two different pathways depending on the scan rate. At scan rates higher than 20 mV/s, the reduction proceeds via [SnIIX2Cl2]2- and [Sn0X(H2O)2]-, and at slower scan rates the reduction proceeds via [SnIIXCl3]2- and [Sn0Cl(H2O)2]-. This is the first time that experiments have indicated the existence of tin0 complexes. The studied tinIV complex can be used for the determination of tin traces in aqueous solutions. Therefore the tinIV complex is preliminarily extracted from aqueous solution and the differential pulse anodic stripping voltammograms are recorded in the organic solution after addition of 2-propanol. The 3σ limit of detection is 4 × 10-8 mol/L.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140070306
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  • 8
    Digitale Medien
    Digitale Medien
    Staircase voltammetry with finite diffusion space (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 575-577 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Staircase voltammetry ; Thin-layer cell ; Finite diffusion space ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A theory of the staircase voltammetry in a thin-layer cell is developed. The influence of the cell thickness and the redox reaction rate constant on the current and the peak potentials is analyzed. For moderately thick cells, the kinetic maximum is predicted. The relationship between peak currents and the square root of the scan rate is not linear and the response may entirely vanish if the redox reaction is fast, the cell is very thin and the scan rate is slow.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140090715
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  • 9
    Digitale Medien
    Digitale Medien
    The application of abrasive stripping voltammetry for a simple and rapid screening of pesticides (1996)
    Weinheim : Wiley-Blackwell
    Electroanalysis 8 (1996), S. 955-958 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Abrasive stripping voltammetry ; Screening ; Chlorothion ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Abrasive stripping voltammetry has been employed to describe a simple and rapid solid-state voltammetric procedure for the screening of pecticides. A particular case of chlorothion studied on cucumber and lettuce is discussed in this communication. The procedure described provides a semiquantitative assessment and obviates the need to bring the substrate into solution.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140081021
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  • 10
    Digitale Medien
    Digitale Medien
    A graphite silver(I) hexacyanoferrate(III) composite electrode for the determination of iron (III) ions (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 922-925 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Iron ; Reactive electrode ; Silver hexacyanoferrate ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A reactive electrode (reactrode) made of silver(i) hexacyanoferrate(III) (Ag-hcf), graphite and paraffin has been developed for the determination of iron(III) ions in solutions down to a concentration of 0.12 mg L-1. Silver ions are reduced to Ag0 and the liberated hecacyanoferrate ions react with iron(III) ions from the solution to form Prussian blue. After this preconcentration step, the iron ions can be determined electrochemically by the characteristic signals of Prussian blue in differential pulse voltammetry. A nonlinear calibration plot is obtained which has a standard deviation of 13%. Pb2+, Cu2+ and Ni2+ interfere when they are at the same concentration as iron(III), whereas Cd2+ does not interfere even at higher concentrations. The incorporation of an active reagent into the electrode material remarkably facilitates the analytical procedure and makes the use of a mercury electrode unnecessary.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140091211
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