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  • 1985-1989  (8)
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Year
  • 1
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    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: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 60 (1988), S. 2567-2572 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 324 (1986), S. 832-838 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Experiments are carried out where hydrides are collected in a cold trap, revolatilized, and conducted into a heated quartz tube with a controlled stream of pure or mixed gases. In the presence of hydrogen, atomization proceeds via hydrogen radicals formed in the quartz tube in a rather restricted area. Lifetime of the analyte atoms is at least three orders of magnitude longer than that of the H radicals. In the absence of hydrogen the hydrides are thermally decomposed but only in part atomized. The species formed during the thermal decomposition, probably an oxide and/or the element, are retained in the heated quartz tube to essentially 100%. The deposited species can be re-volatilized and atomized in part when hydrogen enters the heated quartz tube at a later time.
    Notes: Zusammenfassung Es wurden Versuche durchgeführt, bei denen die Hydride in einer Kühlfalle gesammelt, wieder verflüchtigt und mit einer kontrollierten Strömung reiner oder gemischter Gase in ein beheiztes Quarzrohr geleitet werden. In Gegenwart von Wasserstoff erfolgt die Atomisierung über H-Radikale, die sich in einer begrenzten Zone in dem Quarzrohr bilden. Die Lebensdauer der Analytatome ist mindestens drei Größenordnungen länger als die der H-Radikale. In Abwesenheit von Wasserstoff werden die Hydride thermisch zersetzt, aber nur teilweise atomisiert. Die bei der thermischen Zersetzung gebildete Substanz, wahrscheinlich ein Oxid oder das Element, verbleibt praktisch zu 100% in dem beheizten Quarzrohr. Die abgelagerte Substanz kann teilweise wieder verflüchtigt und atomisiert werden, sobald Wasserstoff in das beheizte Quarzrohr gelangt
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 327 (1987), S. 246-252 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of glassy carbon as a tube material in electrothermal atomic absorption spectrometry requires modifications to the power supply if temperatures and heating rates comparable to those for graphite tubes are to be obtained. Glassy carbon tubes frequently have a longer lifetime than pyrolytic graphite coated tubes made of polycrystalline electrographite. Peak height sensitivity for glassy carbon is better by a factor of two for some volatile elements, but up to a factor of five inferior for less volatile elements than that for pyrolytic graphite coated tubes. Peak area sensitivity is generally inferior by about a factor of two. Sample volume is limited to 5–10 μl because of the smooth surface. From the signal shape it can be deduced that adsorption of analyte atoms at the tube wall plays an important role in glassy carbon, and is responsible at least in part for the lower sensitivity. Non-spectral interferences can be less pronounced in glassy carbon tubes for those interferents which interact with graphite tube surfaces. Glassy carbon is, however, no alternative to pyrolytic graphite coated tubes.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 325 (1986), S. 95-101 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The analyte addition technique is frequently used in atomic absorption spectrometry, and is often applied routinely to avoid errors in graphite furnace and other techniques for trace element determination. In fact, however, the analyte addition technique can be applied reasonably only if certain prerequirements are fulfilled. The two most important basic rules are that the analyte addition technique can only correct for multiplicative but not for additive systematic errors, and that the added analyte element and the element present in the sample must behave in an analytically identical manner. Careful isoformation is typically required in the graphite furnace technique to fulfil this second requirement. Doing so, however, completely eliminates numerous interferences if at the same time proper atomization conditions and evaluation of integrated absorbance signals are used. This means that the analyte addition technique has become redundant in this case, and that the analytical curve technique can be used for evaluation.
    Notes: Zusammenfassung Das Additionsverfahren wird in der Atomabsorptionsspektrometrie sehr häufig verwendet und in der Graphitrohrofentechnik und anderen Techniken der Spurenelementbestimmung oft routinemäßig zur Vermeidung von Fehlmessungen eingesetzt. In Wirklichkeit ist das Additionsverfahren aber nur dann sinnvoll einsetzbar, wenn gewisse Vorbedingungen erfüllt sind. Die zwei wichtigsten Grundregeln sind, daß das Additionsverfahren nur multiplikative, nicht aber additive, systematische Fehler beseitigen kann sowie daß sich der zugesetzte Analyt und der in der Probe vorhandene analytisch identisch verhalten müssen. Um diese zweite Bedingung zu erfüllen, muß bei der Graphitrohrofentechnik üblicherweise eine sorgfältige Isoformierung erfolgen. Dadurch werden aber, bei gleichzeitigem Einhalten günstiger Atomisierungsbedingungen und Auswertung der integrierten Extinktion, zahlreiche Störungen vollständig beseitigt. Das bedeutet, daß das Additionsverfahren in diesem Fall überflüssig geworden ist und die Auswertung nach dem Standard-Kalibrierverfahren erfolgen kann.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 331 (1988), S. 324-329 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sodium tetrahydroborate(III) is equivalent to or better than tin(II) chloride as a reducing agent for mercury in cold vapor atomic absorption spectrometry using collection on gold. Concentrations of copper, silver, nickel, iodide, antimony, arsenic, bismuth and selenium typically found in water or waste water do not interfere. Prerequirements for satisfactory performance are that the gold is at a temperature below 100
    Type of Medium: Electronic Resource
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