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  • 1
    Electronic Resource
    Electronic Resource
    Site preference of metastatic tumours of the brain (1988)
    Springer
    Virchows Archiv 412 (1988), S. 493-498 
    Details
    ISSN: 1432-2307
    Keywords: Brain neoplasms ; Secondary tumours of the brain ; Primary tumour dependent site preference ; Metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Amongst 15000 autopsies performed between 1969 and 1984 in the Department of Pathology of the University Hospital of Innsbruck (Austria) 237 cases (1.6%) with brain metastases were found. The mean age of patients was 61.2 years and 148 patients out of 230 cases with satisfactory records were male (64.3%). Multiple lesions were found in 58%. In absolute figures carcinoma of the lung, followed by malignant melanoma and breast carcinoma were, as in other series, the most frequent primary site for brain metastases. The relative frequency of brain metastases in various anatomical regions of the brain showed that malignant melanoma tends to metastasize to the frontal and temporal lobes, breast carcinoma to the cerebellum and the basal ganglia, large cell carcinoma of the lung to the occipital lobe and squamous cell carcinoma of the lung to the cerebellum. Metastases of small cell carcinoma of the lung were found equally distributed in all regions of the brain. Our study supports the results of several experimental investigations, suggesting the possibility that specific cell surface properties of metastasizing tumour cells and particular properties of the vascular endothelium of the target organs of metastasis are responsible for the location of metastases. The results of this study suggest that there are substantial differences in regard to these properties even within one target organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750584
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  • 2
    Electronic Resource
    Electronic Resource
    A Potentiometric Detection Technique for Chelating Agents after Separation by Capillary Zone Electrophoresis (1998)
    Springer
    Monatshefte für Chemie 129 (1998), S. 811-816 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Capillary electrophoresis; Potentiometric detection; Chelating agents; Aminopolycarboxylic acids.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Für die Bestimmung von Chelatbildnern wie Diethylentriaminpentaessigsäure wurde die Kombination der Kapillarzonenelektrophorese mit einer selektiven potentiometrischen Detektionstechnik untersucht. Der Detektor beinhaltet eine metallische Kupferelektrode mit einem Durchmesser von 100 μm, welche in einer end-capillary-Anordnung positioniert ist. Das Elektrodenpotential hängt von der Konzentration freier Kupferionen an der Elektrodenoberfläche ab und sinkt daher, wenn komplexierende Analyte die Elektrode passieren. In Verbindung mit einer UV-Detektion ist die simultane Erfassung von freien Liganden und deren Metallkomplexen möglich.
    Notes: Summary.  The combination of capillary zone electrophoresis with potentiometric detection has been investigated for the determination of chelating agents such as diethylenetriaminepentaacetic acid. The detector consists of a metallic copper electrode with a diameter of 100 μm arranged in an end-capillary configuration. The electrode potential depends on the concentration of copper ions at the electrode surface and therefore decreases when chelating agents pass the electrode. In combination with UV detection, both free ligands and metal complexes could be detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013488
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  • 3
    Electronic Resource
    Electronic Resource
    Capillary Electrochromatography of Pyrimidine Derivatives Using UV and Mass Spectrometric Detection (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 155-163 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Capillary electrochromatography; Pyrimidines; Atmospheric pressure ionization mass spectrometry; Capillary coupling.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The separation of pyrimidine derivatives by capillary electrochromatography (CEC) using either UV or mass spectrometric detection is described. For UV detection an aqueous phosphate carrier electrolyte containing acetonitrile is employed. The results are compared to the analysis of the same compounds by micellar electrokinetic chromatography in terms of selectivity, migration times, linearity, and detection limits. For the combination of CEC and mass spectrometry (MS) an inexpensive way to couple commercially available instruments is presented; the interface consists of an electrically grounded stainless steel connector (containing a stainless steel frit) serving as the electrode and coupling the CEC capillary with a fused silica transfer capillary to the MS instrument. Alternatively, a PEEK adapter combining the CEC capillary and a grounded stainless steel transfer capillary serving as the electrode is employed. To avoid the formation of hydrogen gas at the coupling piece or the transfer capillary, p-benzoquinone is added to the carrier electrolyte consisting of aqueous ammonium acetate and acetonitrile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007060050016
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  • 4
    Electronic Resource
    Electronic Resource
    Anion Exchange Solid Phase Extraction of Humic Substances for the Determination of Complexed Heavy Metals in Natural Waters with High Dissolved Organic Carbon Contents (1998)
    Springer
    Monatshefte für Chemie 129 (1998), S. 597-605 
    Details
    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
    URL: http://dx.doi.org/10.1007/PL00013463
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  • 5
    Electronic Resource
    Electronic Resource
    Electrochemical detectors – tailormade techniques for liquid chromatography and capillary electrophoresis? (1996)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 354 (1996), S. 797-802 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Electrochemical detectors for liquid chromatography and capillary electrophoresis are reviewed with special emphasis on electrode materials that allow the amperometric detection of otherwise non-electroactive compounds such as aliphatic alcohols, carbohydrates or amino acids. Noble metal electrodes can catalyze the oxidation of aliphatic compounds in alkaline media if multistep potential-time waveforms are employed. Various metal and metal oxide electrodes such as Ni, Cu or Co allow the detection of carbohydrates and similar compounds under constant potential conditions. Metallic copper electrodes operating in an amperometric mode or in a potentiometric mode can also serve as selective detectors for complexing species. A range of applications in combination with chromatography and electrophoresis is summarized. The current state of electrochemical detectors indicates that both amperometric and potentiometric detectors are on the verge of becoming tailormade detectors for micro-separation techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0021663540797
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  • 6
    Electronic Resource
    Electronic Resource
    Metal ion capillary zone electrophoresis with direct UV detection: Separation of metal cyanide complexes (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 153-156 
    Details
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Metal cyanide complexes ; Metal ion analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of cyanide complexes of iron(III), copper(I), iron(II), nickel(II), chromium(III), mercury(II), palladium(II), silver(I), cadmium(II), zinc(II), cobalt(II), and cobalt(III) have been separated by capillary zone electrophoresis using a fused silica capillary and 20 mM phosphate buffers containing 1-2 mM sodium cyanide. The complexes were detected by direct UV absorpticn at 214 nm; detection limits are in the mid ppb range for all metals except cadmium and zinc. The different detectability of various metal cyanide complexes enables the application of the method to the analysis of complex matrices such as cyanide plating bath solutions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160304
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of Low-Molecular-Mass Phenolic and Non-Phenolic Lignin Degradation Compounds in Wood Digestion Solutions by Capillary Electrophoresis (2000)
    Springer
    Microchimica acta 135 (2000), S. 45-53 
    Details
    ISSN: 1436-5073
    Keywords: Key words: Capillary electrophoresis; lignin degradation; wood digestion.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract.  Different capillary electrophoretic techniques were investigated and compared for the separation of low-molecular-mass phenolic and neutral lignin degradation compounds. Simple capillary zone electrophoresis (CZE) was not suited for this problem. Switching to micellar electrokinetic capillary chromatography (MEKC) by adding micelle-forming reagents to the carrier electrolyte enhanced the separation performance considerably. Alternatively, microemulsion electrokinetic chromatography (MEEKC) was investigated. This is a CE technique in which analytes interact with moving oil droplets present in a microemulsion buffer. Using the optimized carrier electrolyte systems and a 60 cm×50 μm I.D. bubble cell capillary it was possible to analyse solutions of different wood digestion procedures and to investigate differences in lignin degradation products during use of different kinds of wood (eucalyptus, beech, scotch pine and acacia).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006040070017
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  • 8
    Electronic Resource
    Electronic Resource
    Trace analysis of ioxynil and bromoxynil using HPLC with electrochemical and UV detection (1984)
    Springer
    Microchimica acta 82 (1984), S. 53-61 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine Methode für die Bestimmung von Rückständen von Bromoxynil und Ioxynil in Gerstenmatrices wird beschrieben. Die Proben werden mit Aceton extrahiert; Verteilung zwischen Wasser und Chloroform/Dichlormethan, Gelchromatographie an Polystyrol-Divinylbenzol-Gel und Flüssigkeitschromatographie an nitrilmodifiziertem Kieselgel werden zur Reinigung der Extrakte verwendet. Die Verbindungen werden mittels Umkehrphasen — HPLC mit elektrochemischer und UV-Detektion bestimmt. Die Bestimmungsgrenzen liegen bei 50 ppb.
    Notes: Summary A method for the determination of residues of bromoxynil and ioxynil in barley matrices is described. Samples are extracted with acetone; partition between water and chloroform/dichloromethane, gel permeation chromatography on a polystyrene-divinylbenzene gel and liquid chromatography on nitrile-modified silica are used for clean up of the sample extracts. The compounds are determined by reversed phase HPLC with electrochemical and UV-detection. Determination limits are in the range of 50 ppb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01202161
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of chelating agents and metal chelates by capillary zone electrophoresis (1995)
    Springer
    Microchimica acta 119 (1995), S. 103-111 
    Details
    ISSN: 1436-5073
    Keywords: aminopolycarboxylic acids ; metal chelates ; capillary zone electrophoresis ; waste water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Aminopolycarboxylic acids such as diethylenetriaminepentaacetic acid (DTPA) are commonly used as chelating agents in many pulp and paper industries, particularly as scavengers of metal ions which catalyze the decomposition of hydrogen peroxide used as a bleaching agent. Concern for the effect of waste DTPA in the aquatic environment has led to a need for the development of methods to determine its levels in waste water. This paper describes the determination of free DTPA and several metal-DTPA complexes in water and waste water by capillary zone electrophoresis. The optimization of separation conditions included the selection of an appropriate carrier electrolyte composition (pH, organic solvents, ion-pairing reagents) and the systematic investigations of selective complexation of free DTPA as well as metal exchange reactions for metal-DTPA complexes in order to achieve selective and sensitive direct UV detection. The determination of DTPA in waste water from a paper mill was possible in the low ppm range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244859
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of free fatty acids by capillary zone electrophoresis (1996)
    Springer
    Microchimica acta 122 (1996), S. 45-52 
    Details
    ISSN: 1436-5073
    Keywords: free fatty acids ; dairy products ; capillary electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Capillary zone electrophoresis was investigated for the separation of free fatty acids as an alternative to well established techniques such as GC or HPLC. The analysis was performed with indirect UV detection in a counterelectroosmotic flow mode using a diethylbarbiturate carrier electrolyte at a pH between 10 and 11 in a mixed aqueous-organic solvent. Separation of saturated and unsaturated fatty acids could be achieved after bromination of the double bonds. Problems with wall adsorption of fatty acids could be overcome by increasing the temperature and using a high concentration of a zwitterionic reagent to inactivate the silica surface. Increased sensitivity could be achieved after preconcentration on alumina. The method was applied to the determination of free fatty acids in dairy products. The advantages compared to traditional methods include short analysis times and simple preparation steps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01252404
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