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  • Electronic Resource  (12)
  • Chemistry  (12)
  • 1
    Electronic Resource
    Electronic Resource
    Immobilized enzyme carbon paste electrodes as amperometric sensors (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 319-323 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The construction and performance of new carbon paste enzyme electrodes as amperometric sensors is described. Xanthine oxidase and alkaline phosphatase have been adsorbed on a carbon paste electrode (CPE), and physically entrapped with a semipermeable membrane. The product of enzymatic reaction, uric acid or p-nitrophenol, was electrochemically oxidized versus an Ag/AgCl electrode at +0.4 or +0.8 V, respectively, yielding a steady-state current directly related to the substrate concentration. Response characteristics as well as kinetic parameters have been evaluated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030412
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Direct determination of bentazepam in a biological sample with a sepiolite-modified carbon paste electrode (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 643-646 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon paste electrodes (CPEs) modified with sepiolite are employed for adsorptive accumulation and voltammetric determination of the drug bentazepam. Response variables are explored, and measurements in urine samples are illustrated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020812
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of different cross-linking systems on properties of highly saturated nitrile rubber compounds (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1073-1078 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The peroxide curing of highly saturated nitrile rubber was analyzed. Reactions such as chain scission occurred that account for the drop in physical properties. The results are compared with an alternative cross-linking that is currently being assessed. With a new curing agent the chain-scission reaction was not present and the properties of the compounds were improved. Finally, an estimation of the free volume of the materials tested was attempted by using the WLF equation. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070540809
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  • 4
    Electronic Resource
    Electronic Resource
    Direct determination of indole-3-acetic acid in plant tissues by electroanalytical techniques using a carbon paste modified with OV-17 electrode (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 577-583 
    Details
    ISSN: 1040-0397
    Keywords: OV-17 carbon paste modified electrode ; Differential pulse voltammetry ; Indole-3-acetic acid determination ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical behavior of indole-3-acetic acid (IAA) with a silicone OV-17 modified carbon paste electrode was explored for the determination of this compound in plant tssues. Under optimum conditions, the procedure gave a linear concentration range up to 0.6 μg mL-1 detection of 0.053 μ mL-1 containing the preconcentration solution 0.08M Hac/Ac- buffer (pH4) and 0.4 M phosphate buffer (pH12) as a supporting electrolyte in the measurement cell. The accumulation time was 10 minutes and the sweep potentials were carried mV s-1 with a pulse amplitude (ΔE) of 100 mV. This method is available for the determination of IAA in plant tissues.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060708
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of dimethoate in water by cathodic stripping square-wave voltammetry (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 51-55 
    Details
    ISSN: 1040-0397
    Keywords: Cathodic stripping square-wave voltammetry ; Dimethoate ; River water ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes the direct-determination of the pesticide dimethoate In river water in an alkalin media and accumulaton medium through cathodic stripping voltammetry. By employing an alkaline potential of 30 mV, reduction peak appears at -0.7 V. The detection limit is 1 ng ml-1.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060110
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  • 6
    Electronic Resource
    Electronic Resource
    Indirect determination of ephedrine in urine by differential pulse polarography (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 1214-1218 
    Details
    ISSN: 1040-0397
    Keywords: Ephedrine ; N-Nitrosoephedrine ; Differential pulse polarography ; Nitrosation ; Urine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nitrosation of ephedrine and the electrochemical reduction of N-nitrosoephedrine were investigated by differential pulse polarography and have been optimized in order to attain the optimum analytical signal. Reduction of the N-nitrosoephedrine was carried out in one irreversible, diffusion-controlled step using potassium chloride-hydrochloric acid. In 0.1 M hydrochloric acid the N-nitrosoephedrine shows a well-defined reduction peak at -0.77 V (vs. Ag/AgCl/ 3 M KCl). An indirect differential-pulse polarographic method is described for the determination of ephedrine at levels higher than 2.5 μg per mL of urine. An extraction procedure with C18 cartridge and a fast and easy nitrosation reaction with sodium nitrite in 0.2 M phthalate potassium hydrogen is also described. Determination of 5 μg/mL of N-nitrosoephedrine in urine samples of 4 mL was possible using the standard addition method, with a relative error of -4.0% and relative standard deviations no higher than 2.1%.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140091518
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of paraquat by cathodic stripping voltammetry after accumulation through the formation of an ion pair on a hanging mercury drop electrode (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 79-83 
    Details
    ISSN: 1040-0397
    Keywords: Stripping voltammetry ; Ion pair ; Paraquat ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of ion pairs is used to greatly enhance the sensitivity of cathodic stripping measurements at the hanging mercury drop electrode (HMDE). Such a scheme is illustrated for the trace determination of paraquat. Factors affecting the response are explored.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050112
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  • 8
    Electronic Resource
    Electronic Resource
    Electroanalytical determination of lormetazepam in pharmaceutical preparations and human urineDedicated in memory of Prof. G. Patriarche. (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 811-817 
    Details
    ISSN: 1040-0397
    Keywords: Lormetazepam ; voltammetry ; urine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical properties of the drug lormetazepam have been studied at the mercury electrode. A method for determination of the drug in commercial preparations by differential pulse polarography has been devised, with mean relative errors lower than 1.4% and relative standard deviations lower than 3.3%. Controlled adsorptive accumulation of lormetazepam at a hanging mercury drop electrode (HMDE) provided the basis for its determination by stripping voltammetry at nanomolar concentration levels. The adsorptive stripping response was evaluated with respect to experimental conditions and parameters such as electrolyte, pH, accumulation potential, accumulation, time and concentration. A drug determination method for use in urine with previous extraction (98% recovery) has been developed, with a detection limit of 23 ngm·1-1 (40 second accumulation time) and a relative standard deviation around 6.8%.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040812
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of silica by acid dissolution of sepiolite and study of its reinforcing effect in elastomers (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 103 (1982), S. 51-60 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Herstellung von amorpher Kieselsäure durch saure Behandlung von Sepiolit, einem natürlichen Magnesiumsilikat, und ihre Verwendung als verstärkender Füllstoff für Naturkautschuk- und Styrol-Butadienkautschuk-Mischungen wurden untersucht. Die Geschwindigkeitskonstante der Magnesiumextraktion durch Salpetersäure bei verschiedenen Temperaturen und Säurekonzentrationen und die Aktivierungsenergie wurden ermittelt.Das Endprodukt besteht weitgehend aus amorpher Kieselsäure (92,5% SiO2), wie durch Röntgenanlyse bestätigt wurde; die faserige Morphologie des Ausgansminerals wird beibehalten. Wie eine kurze technologische Untersuchung zeigte, ist die erhaltene Kieselsäure als verstärkender Füllstoff für Allzweckkautschuke geeignet; die Ergebnisse wurden mit jenen aus handelsüblicher gefällter Kieselsäure verglichen. Die Einwirkung von Silan-Haftvermittlern auf die neue Kieselsäure wurde ebenfalls untersucht.
    Notes: The preparation of amorphous silica by acid treatment of a natural magnesium silicate and its use as reinforcing filler for NR and SBR compounds are studied. Limited to the treatment with nitric acid, the rate constants at different temperatures and acid concentrations and the activation energy are calculated, as a function of percentage of extracted magnesium.The resulting material is basically an amorphous silica (92.5% SiO2), as shown by X-ray analysis, that keeps the fibrous morphology of the original mineral. According to a preliminary technological study the resulting silica is a suitable reinforcing filler for general purpose rubbers; a comparison between the experimental results and those obtained with a commercial fine particle precipitated silica was made. Using a SBR compound the effect of silane coupling agents on the new silica was studied.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051030105
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of mineral filler sepiolite on sulphur-free thiuram vulcanization of natural rubber (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 104 (1982), S. 189-201 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von Sepiolit auf die schwefelfreie Vulkanisation von Naturkautschuk durch Tetramethylthiuramdisulfid, mit und ohne Aktivator (Triethanolamin), wurde untersucht. Dabei wurde der Sepioliteinfluß auf die a) kinetischen Vulkanisations-Parameter, b) Vernetzungsdichte, c) Art der Vernetzungsbrücken, d) Vernetzungs-ausbeute E und e) Bildung von Zinksulfid studiert. Mit zunehmendem Sepiolit-Anteil wächst die Vulkanisationsgeschwindigkeit, während die Vernetzungsdichte abnimmt. Aufgrund dieser Ergebnisse wird der Mechanismus der Vulkanisation diskutiert.
    Notes: The effect of sepiolite on the sulphurless vulcanization of NR by tetramethylthiuram disulphide, with and without activator (triethanolamine) was studied. The influence on: a) kinetic vulcanization parameters, b) crosslinking density, c) crosslinking types, d) efficiency factor E and e) zinc sulphide formation was considered. The vulcanization rate increases with increasing sepiolite level but crosslinking density is reduced. Based on these results a vulcanization mechanism is proposed and discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051040116
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