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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 529 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-4475
    Keywords: Keywords. Humic substances; Heavy metals; Solid phase extraction; Anodic stripping voltammetry.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Für die Festphasenextraktion von Humin- oder Fulvinsäure-Schwermetallkomplexen aus Wasser wurde ein Sorbens auf Basis eines Copolymeren von Styrol und Divinylbenzol entwickelt. Das Material wurde durch eine modifizierte mehrstufige Schwellmethode synthetisiert; die Anionenaustauschfunktionalitäten wurden durch chemische Modifizierung oder durch Belegung der Partikeloberfläche eingeführt. Diese Sorbentien ermöglichten die Extraktion von Huminstoffen bei ihren natürlichen pH-Werten; das Eluat oder die Festphase gemeinsam mit den Huminstoffen wurde mittels Schwefelsäure verascht (Trockenveraschung). Die Bestimmung der Metalle Cu, Zn, Pb und Cd erfolgte nach dem Verfahren der inversen Differentialpulsvoltammetrie. Mit dieser Methode konnten die vier Metalle mit Wiederfindungsraten zwischen 87 und 99% bei Konzentrationen bis hinunter zu 50 ng/l bestimmt werden.
    Notes: Summary.  A solid phase extraction material based on a copolymer of styrene and divinylbenzene was developed for the extraction of heavy metals complexed by humic and fulvic acids in water. The sorbent was synthesized by a modified multistep activated swelling polymerization procedure; anion exchange functionalities were introduced by chemical modification or by coating of the particle surface. These materials allowed the extraction of humic substances from water samples at their natural pH. The extract or the sorbent containing the humic substances was digested by dry ashing with sulfuric acid, and the metals Cu, Zn, Pb, and Cd were determined by differential pulse anodic stripping voltammetry. With this method, the four metals could be determined with recoveries between 87 and 99% at concentrations down to 50 ng/l.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Analytical methods are described for the quantitative determination of putrescine, cadaverine, spermidine, spermine and the acetylated derivatives of spermidine and spermine in biological fluids using pre-column derivatization with either benzoyl chloride or 3,5-dinitrobenzoyl chloride, which were added to each sample as solutions in diethyl ether. Putrescine, spermidine and spermine can be analysed in seminal plasma at nanogram levels when benzoyl chloride is used as derivatizing agent. In the analysis of putrescine, cadaverine, spermidine and acetyl derivatives of spermidine and spermine, higher sensitivity is obtained with 3,5-dinitrobenzoyl-chloride. This method can readily be used in the determination of acetylated polyamines in urine samples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 30 (1990), S. 469-470 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 5-5 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 131-136 
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Kraft process liquors ; Inorganic anions ; Sulfur specification ; Direct and indirect detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various sulfur containing anions (sulfate, sulfite, and thiosulfate) in Kraft pulping process liquors are determined by capillary electrophoresis. In addition, other inorganic anions (hydroxide, chloride, oxalate, carbonate) are analyzed with the developed method. Through optimization of the separation conditions it is possible to simultaneously determine these anionic species in pulping liquors with direct and indirect UV detection at 185, 214, and 254 nm. To ensure short separation times a migration of the anionic analytes in the same direction as the electroosmotic flow (co-electroosmotic CE) is established by reversal of the electroosmotic flow with 1,5-dimethyl-1,5-diazaundecamethylene polymethobromide (hexadimethrine bromide; HDB; polybrene™) which is added to the electrolyte as EOF modifier. The impact of acetonitrile as organic modifier to improve the selectivity of the anionic analytes is also investigated. The developed method is then applied to analyze and quantify various anions in pulping liquors (white and black liquors). By simultaneously determining the hydroxide concentration it is possible to calculate effective alkalinity and sulfidity with the measured concentrations without the need of volumetric methods.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 177-179 
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Chromium speciation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 3-10 
    ISSN: 0935-6304
    Keywords: Co-electroosmotic capillary electrophoresis ; high performance liquid chromatography ; phenolic lignin degradation compounds ; inorganic anions ; organic modifiers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Two methods are presented for the quantitative capillary electrophoretic (CE) determination of phenolic lignin degradation compounds as well as of inorganic anions and organic acids in Kraft black liquors. Important phenolic lignin degradation compounds can be rapidly separated by co-electroosmotic CE after acidification of the liquors and subsequent extraction of the compounds with chloroform. A capillary electrophoretic separation of phenolic compounds is performed by using a phosphate/borate electrolyte system and UV detection at 214 nm. In addition, a HPLC method using a gradient with water, methanol, and acetic acid is also developed. Inorganic ions which are of importance to the pulping process can be determined by simply diluting the black liquors after sampling and subsequent analysis with a chromate electrolyte system and indirect UV detection at 185 nm. In addition, the concentration of low molecular aliphatic carboxylic acids can be determined simultaneously within the same run. By method optimization it is possible to separate the anions within one minute and, at the same time, to increase the resolution of the solutes. The electrolyte systems for the CE separations were optimized by varying the pH value and by adding organic solvents. Short separation times are obtained by adding a polycationic EOF modifier (hexadimethrine bromide) to the electrolyte which reverses the electroosmotic flow. A migration of the anionic analytes in the same direction as the electroosmotic flow is thus established.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 35-38 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Combining the effects of electrophoresis and electroendosmosis, flavonoids were separated in less than ten minutes in a fused silica capillary tube with a borate buffer adjusted to pH 10. An increase in the concentration of borate from 0.1 to 0.2 M resulted in longer migration times due to a decrease in electroosmotic flow, but also in improved selectivity and higher resolution of flavonoids. The calibration curve of rutin showed a detection limit of 0.02 mg/mL and linearity over its pharmaceutical concentration range. Using an internal standard of known concentration, the content of rutin in a methanolic extract of Sambuci flos could be determined with a coefficient of variation as small as 3.8% by the molar ratio - peak area ratio method.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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