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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemometrics and Intelligent Laboratory Systems 8 (1990), S. 79-86 
    ISSN: 0169-7439
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemometrics and Intelligent Laboratory Systems 24 (1994), S. 197-203 
    ISSN: 0169-7439
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytica Chimica Acta 219 (1989), S. 273-279 
    ISSN: 0003-2670
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract For successful application of simultaneous ICP atomic emission spectrometry for major component determinations in multi-component materials the accuracy of the method has to be improved. As a contribution to solve this problem a combined procedure for multi-component standard sample preparation, optimum calibration and different variations of internal standard corrections is described. Variance-weighted multi-line calibrations give most accurate results. Internal standard corrections are effective, if the time-dependent spectral line intensity fluctuations of the standard and the analyte elements are well correlated. Their sensitivities against some responsible device parameter variations are investigated. On the basis of multi-line measurements of the analyte and internal standard elements a “group-selected internal standard correction” (GS-ISC) method is applied and results in relative errors of less than 1% even for extreme fluctuations of the raw intensities. For rapid routine determination methods of materials with variable element compositions the added line intensities of the internal standard element can be used to correct the added analyte line raw intensities (“intensity addition internal standard correction” (IA-ISC) method). These accuracy optimization procedures are applied for the analysis of the soft magnetic material permalloy using the internal standard element In.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 366 (2000), S. 146-151 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract For quality tests of ceramic Bi-Pb-Sr-Ca-Cu-O superconductor materials (precursors and final products) accurate stoichiometric determinations of the metallic major components are necessary. Three methods were developed during the last decade in our group. Their properties and the results obtained are compared. The first classical analytical procedure requires to much manpower. The second combined chemical-spectrometric procedure is a routine method today, but also unsuitable for rapid tests. A new fully spectrometric procedure was recently developed using a simultaneously working Echelle spectrometer with CID detector, autosampler and a special self-made data evaluation software. The basis of this method are multi-line measurements of each analyte element, a new method of spectral line selection for main component precision determinations, multi-component calibrations, and frequent external standardizations. For this method the sum of the confidence intervals of all element determinations was less than 1%, and no systematic error was detected.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 69-73 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  To characterize the real stoichiometry of ceramic high-temperature superconductors of the Y-Ba-Cu-O type and the Bi(Pb)-Ca-Sr-Cu-O type complex, chemical methods including digestion, separation and subsequent titrimetric determination of the elemental components were investigated. Using optimized automatic titration procedures with photometric, potentiometric or voltametric equivalence point detection, a high accuracy of the analytical results could be achieved. The random as well as the systematic errors are less than 0.5%. The exact stoichiometric coefficients of the components and thereby the phase compositions or the single phase character of the materials were determined and compared with the results of X-ray diffraction measurements.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 249 (1970), S. 22-25 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Oxydation von Tiron mit Wasserstoffperoxid wird zur Bestimmung von Kobaltspuren nach einer integralen kinetischen Methode verwendet. Eichkurven in den Bereichen 12-1, 1,2-0,1 und kleiner als 0,12 ng Kobalt/ml werden durch Messung der Extinktion des Tiron-Oxydationsproduktes bei 336 nm nach festgelegten Reaktionsdauern von 4 min, 1 und 24 h in Abhängigkeit von der Kobaltkonzentration erhalten. Die Standardabweichungen für die drei Meßbereiche betragen 0,5, 0,04 und 0,016 ng Kobalt/ml, und die Erfassungsgrenze des Verfahrens liegt bei 0,03 ng Kobalt/ml. Zur Bestimmung von Kobaltspuren in Molybdän werden die Matrix und die störenden Spurenelemente Eisen und Nickel mit Hilfe eines stark basischen Anionenaustauschers abgetrennt. Auf diese Weise können 4,8·10−6% Kobalt in Molybdän bestimmt werden.
    Notes: Abstract The oxidation of tiron by hydrogen peroxide is applied to the determination of trace concentrations of cobalt by means of an integral kinetic method. Calibration curves in the intervals of 12-1, 1.2-0.1 and less than 0.12 ng cobalt/ml are obtained by measuring the extinction of the oxidation product of tiron at 336 nm after fixed reaction times of 4 min, 1 and 24 h, respectively, as a function of the cobalt concentration. The corresponding standard deviations amount to 0.5, 0.04 and 0.016 ng cobalt/ml and the limit of identification („Erfassungsgrenze“) of the method amounts to 0.03 ng cobalt/ml. For the determination of cobalt traces in molybdenum the matrix and the interfering trace elements iron and nickel are separated by means of a strong basic ion exchanger. In this way 4.8×10−6% cobalt in molybdenum can be estimated.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The applicability of simultaneous ICP-OES for the accurate analysis of soft magnetic alloys has been investigated. Long-time signal variations of up to 40% can be observed under normal operating conditions. The scattering of the values can largely be compensated by a correction procedure with internal and external standardization where the intensity value of the analytical signal is first rationed to the simultaneously measured intensity of an internal standard line and after that recalibrated with an external standard. Not only the trueness but also the precision could be improved by using Cd as a real-time internal standard. This is attributed to a compensation for instrumental fluctuations as a result of the simultaneous measurement of both emission signals.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 355 (1996), S. 281-283 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A study has been made of the feasibilities of automatic microwave-heated acid digestion and simultaneous inductively coupled plasma optical emission spectrometry (ICP-OES) for highly accurate analysis of soft magnetic alloys. The results of the analysis of a nanocrystalline soft magnetic alloy for Fe, B, Si, Cu and Nb were compared to those obtained by the classical chemical analysis methods. It can be shown that the automated digestion and simultaneous ICP-OES fulfil the accuracy requirements in most cases. Moreover, it is demonstrated that the analysis by automated digestion and simultaneous ICP-OES is considerably faster and has a reduced chemical consumption.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 314 (1983), S. 555-559 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Analysenbedingungen für die Zinkbestimmung in Zinkoxidkristallen durch komplexometrische Rücktitration eines etwa 10 %-igen DCTE-überschusses mit aus Reinstzink hergestellter Ma\lösung werden aus den Ergebnissen der Computersimulationen der Titrationskurven (Teil I dieser Publikation) und den gegebenen apparativen Voraussetzungen abgeleitet. Die Titrationen erfolgen bei pH 5,3 mit Xylenolorange als Indicator und photometrischer Indication eines vorgewÄhlten Endpunktes. Die absolute Standardabweichung des Bestimmungsverfahrens betrÄgt 0,03 %. Das Verfahren ist geeignet, die HomogenitÄt von Zinkoxid-Halbleiterkristallen bezüglich Verunreinigungen, z.B. eingeschlossener Fremdphasen, zu charakterisieren. Die Analysen von undotiertem einphasigen Zinkoxid der oberen und der unteren Phasengrenze ergeben jedoch keinen signifikant unterschiedlichen Zinkgehalt.
    Notes: Summary The conditions for the procedure of zinc determination in zinc oxide crystals by complexometric back titration of a 10% DCTA excess with a standard solution prepared from high-purity zinc are derived from the results of computer simulation of titration curves (part I of this paper) and from the apparative suppositions. The titrations are carried out at pH 5,3 with xylenol orange as indicator and with photometric indication of a pre-set end-point. The absolute standard deviation is 0.03%. The method is suitable for characterizing the homogeneity of zinc oxide semiconductor crystals regarding contaminants, for example enclosed foreign phases. However, no significantly different zinc concentrations are obtained from the analyses of undoped single-phase zinc oxide of the upper and the lower phase boundary.
    Type of Medium: Electronic Resource
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