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  • 1990-1994  (13)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 338 (1990), S. 891-894 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A combined procedure enabling simultaneous multielement analysis of trace impurities in high-purity iron is presented. After removal of the iron matrix by solvent extraction with methyl isobutyl ketone, the trace elements Ti, V, Cr, Mn, Ni, Cu, Pb and Bi are determined by means of total reflection X-ray fluorescence analysis. Detection limits are found in the range of 100 ng/g. The reliability of the method is verified by the analysis of commercial high-purity iron and by the comparison of analytical data obtained by ICP-AES.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 342 (1992), S. 569-580 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Four independent procedures including one using slurry nebulization ICP-AES were developed for the trace analysis of ZrO2 powders. They were evaluated with respect to detection limits, blank values, interferences, accuracy and precision. For the procedures I–III ZrO2 powder was decomposed by fusion with a 10-fold excess of NH4HSO4 and subsequent dissolution of the melt in either water or, after evaporation of NH4HSO4, in diluted HNO3. In procedure I the solution was directly analyzed by ICP-AES, which was optimized with the aid of a simplex algorithm. In procedure II Zr was separated by extraction from 6 mol/l HNO3 with a 0.5 mol/l solution of 2-thenoyltrifluoroacetone (TTA) in xylene. More than 99.5% of the Zr was removed and more than 95% of the trace elements retained. In procedure III the matrix was separated by its precipitation as ZrOCl2·8 H2O from a (1:4) HCl-acetone medium. More than 98% of Zr were removed and more than 90% of the trace elements were retained. In procedure IV the ZrO2 powder was dispersed by ultrasonic treatment in water acidified with HCl (pH 2) and the slurry was directly analyzed by ICP-AES using a Babington nebulizer. The optimization and the analytical features of this procedure will be described in a subsequent paper. In all procedures the calibration was performed by standard addition and matrix matching was not necessary. The detection limits varied from 0.3 μg/g (Ca) to 10 μg/g (Al). The standard deviations obtained were 1–10% depending on the element and its concentration in the sample. The results of the procedures for 6 commercially available fine ZrO2 powders were found to agree for Al, Ca, Fe, Mg, Na, Ti and Y. A good agreement between the results of the procedures using matrix separation was also observed for Cu, Mn, V, but the concentrations of these elements found by methods without matrix separation were considerably higher. Except for Ca and Mg the blank values encountered were below the detection limits.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 343 (1992), S. 391-394 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An extremly sensitive procedure for the determination of platinum in human body fluids is presented. A high pressure decomposition of the samples is followed by adsorptive voltammetric measurement. A detection limit down to 0.2 ng Pt/l sample allowed baseline levels of platinum in body fluids (urine: 0.5–15 ng/l, blood and blood plasma: ≤0.8–6.9 ng/l) to be evaluated. The concentration ranges in body fluids of occupationally exposed people were determined to 21–2900 ng/l (urine), 32–180 ng/l (blood) and 95–280 ng/l (blood plasma).
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 343 (1992), S. 778-781 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of a commercially available AAS graphite tube atomizer as an electrode for the cathodic electrodeposition of element traces at constant-current in a hydrodynamic flow-through-system is described. After deposition the graphite tube is transferred into an atomizer unit for subsequent sensitive determination by atomic absorption spectrometry. The deposition yield of ≥99% (2 h; 1.5 A) for Co was verified, using60Co as a radioactive tracer, by monitoring the concentration fall in the electrolyte solution down to ≤5 pg/ml, and the deposited material. The efficiency of the system for the purification of electrolyte solutions was found to be very high. For the determination of the residual impurities, e.g. in very concentrated NH4F-solutions, a simple ion-exchange procedure was worked out for Cu, Mn, Ni, Pb, Zn. To get back the high purity solid NH4F, the solvent was evaporated partly and the precipitated crystals were sucked off in a PTFE-funnel. To avoid contamination, crystallization was carried out in a closed container system using the principle of subboiling distillation. The purity of the recrystallized NH4F-salt increased by a factor of 2 to 3 (crystallization yield 50–70%) so that a solid product with an impurity level below 0.5 ng/g was obtained.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 349 (1994), S. 260-271 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Generating systematic data on incoming materials, processes, production environments and products by contamination monitoring and analyis is the key element of quality assurance in semiconductor fabrication. To be able to match the analytical capabilities to the requirements of improving materials and processes, the level of sophistication of contamination monitoring and analysis systems must be higher than the expected demands in the fabrication line. The accuracy of each analytical method has to be cross-checked by different independent techniques. Accuracy, precision, power of detection, analysis time and expenses should always be tailored to the particular case. All monitoring methods must run under statistical process control. The methods described meet the analytical requirements of the near future in semiconductor grade silicon manufacturing.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 349 (1994), S. 20-25 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The use of plasma atomic spectrometric methods for the analysis of high-purity refractory powders of Al2O3, SiC and ZrO2 used in the production of advanced ceramics is discussed. Special reference is given to the use of combined procedures including sample decomposition and in the case of ZrO2 to matrix removal as well as to the slurry technique as a direct method in atomic spectrometry with inductively coupled plasmas (ICP). Both the possibilities, limitations and analytical use of the slurry technique are discussed and shown to be related to the particle size of the powder; this should be below the 5–10 μm level. The use of a Simplex method for the optimization of the slurry technique towards obtaining both the highest power of detection and calibration using solutions will be treated for the case of SiC. A critical evaluation of the use of ICP atomic emission and of ICP mass spectrometry is presented.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Tobacco, beans, slag and dust samples were digested with nitric and hydrochloric acids in high-pressure PTFE bombs. Pt in the sample solutions was electrochemically deposited at −0.9 to −1.2 V in a flow system incorporating a 3-electrode flow-through cell with a graphite counter and Ag/AgCl reference electrodes. A pyrolytically coated graphite tube packed with reticulated vitreous carbon (RVC) served as the working electrode with the RVC filling axially bored to let the light beam pass through the tube during the AAS measurements. This opening was plugged with a glass rod during the preconcentration step. After the electrodeposition the tube was placed into the graphite furnace and an atomization temperature of 2700°C was applied. The geometry of the cell, flow rate for electrodeposition, deposition potential and electrolyte composition were optimized. The absolute detection limit was found to be about 0.3 ng Pt.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 349 (1994), S. 251-253 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Combustion in fluorine offers a new method for the fast decomposition of several ceramic powders and sintered ceramics. The utilization of this decomposition approach has been investigated as an initial step in wet chemical multi-stage procedures for elemental trace analysis of high purity ceramics. Combustion conditions, element recoveries and blank values from the procedure were studied.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The optimization and use of ICP-AES with slurry nebulization for the direct analysis of ZrO2-powder is described. The powder samples are dispersed in water, acidified to pH 2 and the slurry is fed into a Babington nebulizer. The effects of grain size, pH of the suspending medium and standing time on the stability of the slurry are discussed. For the optimization of the ICP operating conditions, a simplex technique is applied and for this purpose three types of objective functions were examined. Identical behaviour of slurries and solutions with the same matrix concentrations in the ICP-AES is achieved for powders with particle sizes lower than 10 μm; in the latter case calibration can be performed by standard addition with aqueous solutions. The detection limits for Al, B, Ca, Cu, Fe, Mg, Mn, Na, Ti, V. Y are 0.03 μg/g to 10 μg/g and the standard deviation is generally lower than 10%. Six commercially available ZrO2 powders are analyzed by slurry nebulization ICP-AES and the results were found to agree well with those obtained by ICP-AES after chemical decomposition of the samples.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 343 (1992), S. 566-575 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three types of flow-through, three-electrode cells with porous working electrodes made of crushed vitreous carbon were tested. The electrochemical properties of the cells were studied by hydrodynamic and cyclic voltammetry using potassium ferrocyanide test solutions. Depending on the volume of the porous working electrode, Nernstian behaviour and electrochemical yields up to 100% were observed for flow rates 1 to 7 ml/min. In the stopped-flow regime the cells exhibit thin-layer cell properties. The utility of the cells is demonstrated for on-line coulometric detection, continuous removal of impurities and dissolved oxygen and for anodic stripping coulometry of trace copper.
    Type of Medium: Electronic Resource
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