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  • Analytical Chemistry and Spectroscopy  (15)
  • Wiley-Blackwell  (15)
  • American Geophysical Union
  • Elsevier
  • 1
    Electronic Resource
    Electronic Resource
    Species-selectivity effects in the production of electrospray ions (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 363-373 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Positive- and negative-ion production from electrosprayed charged liquid droplets has been studied. For acidified solutions of arginine, Arg-Arg-Arg, Lys-Lys, and (CH3)4NBr in methanol + water (80/20, v/v), the relative intensities of CH3OH2+ ions were found to decrease faster than those of other sample ions as the distance (d) between the capillary tip and the interface plate was increased. The radial distribution of ion intensities in the spray cone was also examined. While the CH3OH2+ ions and multiply charged ions had maximum intensities in the central region of the spray cone, NH4+ and singly charged oligopeptide ions were found to be distributed in its peripheral region. The observed species-selectivity effects in the production of electrospray ions were interpreted in terms of the volatility of ions in the charged liquid droplets. The negative-ion intensities of the oligopeptide Glu-Glu were enhanced greatly when ammonia was added to the solution. An optimum ammonia concentration which gives the strongest negative-ion signals was ∼10-4M.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070511
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  • 2
    Electronic Resource
    Electronic Resource
    Optimization of skimmer voltages of an electrospray ion source coupled with a magnetic sector instrument (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 205-210 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An electrospray ion source designed for a magnetic sector instrument usually has two skimmers, which are located behind a capillary exit with separate pumping stages to reduce the pressure from that of ambient air to a valve suitable for the sector instrument. This work describes an evaluation of these two skimmer voltages with respect to the charge-state distributions and the focusing efficiency of ions. The skimmer voltages were found to be closely related to the m/z values of the detected ions. The optimal difference voltage between skimmers 1 and 2 increased in proportion to the m/z values of the ions, irrespective of the molecular masses of the associated substances. This phenomenon is ascribable to the ion-focusing effect in this region rather than to the effects of energetic collisions in the region of the skimmers, and suggests that the skimmer voltages should be adjusted in accordance with the m/z values of the detected ions for efficient acquisition of all distributed ions. The work demonstrates the functional role of the skimmers in electrospray ionization mass spectrometry with a magnetic sector instrument by examining several types of peptides and proteins, as well as an analysis of a complex mixture of peptides.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080216
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical ionization mass spectrometry of polyunsaturated fatty acids of human serumAbbreviation: DEGS = diethylene glycol succinate polyester. (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 261-264 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyunsaturated fatty acids of human serum were analysed by combination gas-liquid chromatography and chemical ionization mass spectrometry, using isobutane as the reagent gas. The method described yielded the molecular ion of long chain unsaturated fatty acids as the base peak; these were weak or unobservable in the corresponding electron impact mass spectra. In the chemical ionization mass spectromtery, the derivatization with trimethylsilyl ether was demonstrated to be useful for the location of the double bonds of unsaturated fatty acids. Applied to the serum polyunsaturated fatty acids, these methods have given identification of C18:4, C20:4, C20:5, C22:4, C22:5ω-6, C22:5ω-3, and C22:6.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200030602
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  • 4
    Electronic Resource
    Electronic Resource
    Negative-ion fast-atom bombardment tandem mass spectrometry for the structural study of polyether compounds: Structural verification of yessotoxin (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 179-182 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We have examined the applicability of tandem mass spectrometry to the structural elucidation of polyether compounds. The polyether toxin named yessotoxin was isolated from scallops which were implicated in food poisoning. The toxin consists of fused polycyclic ethers as does ciguatoxin, and bears two sulfate esters in the molecule. The negative-ion fast-atom bombardment tandem mass spectrum of the toxin showed a series of ions due to fragmentation at positions characteristic of cyclic ethers. With the mass spectrometric data alone, we succeeded in assigning the number and location of eleven ether rings in yessotoxin, which agreed with those previously deduced by nuclear magnetic resonance studies.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070302
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  • 5
    Electronic Resource
    Electronic Resource
    Optimization of a high speed countercurrent chromatograph for analytical separations (1991)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 306-311 
    Details
    ISSN: 0935-6304
    Keywords: High speed countercurrent chromatography ; Two-phase solvent system ; Column diameter ; Optimization ; Indole auxins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytical capability of the high speed countercurrent chromatograph model 4000 (HSCCC-4000) has been improved by optimizing the dimensions of the multilayer coiled column. Using a two-phase solvent system of n-hexane - ethyl acetate - methanol - water (1:1:1:1) and a set of indole auxins as test samples, a series of studies was conducted to evaluate performance of coiled columns with i.d.s ranging from 0.1 to 0.55 mm. The studies on the stationary phase retention indicated that multilayer coils of 0.55 mm and 0.30 mm i.d. provide satisfactory retention of the stationary phase while the 0.10 mm i.d. column fails to yield reproducible retention. The best partition efficiencies were obtained from the 0.30 mm i.d. multilayer coil with a 6 ml capacity which produced theoretical plate numbers ranging from 5500 to 10500 with a resolution factor of 2.30. The feasibility of interfacing the HSCCC-4000 with a mass spectrometer is briefly discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240140503
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  • 6
    Electronic Resource
    Electronic Resource
    Indium antimonide as an X-ray monochromator (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 4 (1975), S. 74-76 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A single crystal of indium antimonide (zinc blende type InSb) was evaluated as an X-ray monochromator. The long 2d spacing of 7.481 Å makes it possible to diffract Si K α in an ordinary X-ray emission spectrometer. The indium antimonide data were compared with crystals of EDDT, Ge and LiF. Indium antimonide shows seven times higher Si Kα intensity than EDDT. It also has very low second order reflection. A low coefficient of thermal expansion (4.9 × 10-6 °C-1), together with its very stable chemical nature will facilitate high precision measurement ranging from 14Si to 46Pd(Kα), 38Sr to 92U(Lα) and 74W to 92U(Mα).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300040208
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  • 7
    Electronic Resource
    Electronic Resource
    An X-ray fluorescence method for analysis of lead zirconate-titanate compositions (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 3 (1974), S. 109-110 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An X-ray fluorescence method for the determinatios of lead, titanium, zirconium and strontium oxides in lead zirconate-titanate has been developed. The method is a simple empirical correction procedure and requires only one standard containing all the elements analyzed. Moreover, the method does not require prior determination of correction factors obtained by a complex calculation, a multiple regression procedure, or from use of a considerable number of well analyzed standards.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300030304
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  • 8
    Electronic Resource
    Electronic Resource
    An evaluation of X-ray tube spectra for quantitative X-ray fluorescence analysis (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 10 (1981), S. 41-45 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Full spectra including both the continuous and characteristic lines from X-ray tubes are evaluated in a simple way. The penetrating depth of an electron in the target of the X-ray tube is determined and the Kramers' spectrum corrected for the effects of absorption. The characteristic lines are evaluated from a relation between direct electron excitation and indirect excitation by continuous X-rays. The calculated spectra from W and Cu X-ray tubes are given and their usefulness is confirmed by analysing some typical samples including Ag/Pd and Cu/Zn alloys and BaO/TiO2 mixed oxides.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300100110
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  • 9
    Electronic Resource
    Electronic Resource
    Theoretical determination of BA/Ti molar ratios of titanates by X-ray fluorescene spectrometry (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 3 (1974), S. 167-169 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A mathematical approach for determining Ba/Ti molar ratios of barium titanates has been made. A computer program applies the necessary corrections for absorption and secondary fluorescene. The method requires no standards and appears to be sufficiently accurate over large compositional variations. Evaluations of the magnitude of the secondary fluorescence contributions on TiKα intensities are given.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300030409
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  • 10
    Electronic Resource
    Electronic Resource
    A formed filter paper medium for microdroplet analyses of liquid samples by X-ray fluorescence spectrometry (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 11 (1982), S. 159-163 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new type of a formed filter paper is proposed as a sample medium for a microdroplet analysis by x-ray fluorescence spectrometry. It has a circular center part, separated by a narrow circular groove from its edge, and four, paraffined, supporting bridges. It can thus keep a spot area constant when a liquid sample drops at the center part. After dropping the liquid sample, the paper is dried and used for the x-ray measurement. It can be stored for years without any chemical change. This formed filter paper is effective in improving the linearity range of a calibration curve and the precision of a fluorescent x-ray measurement as compared with a non-formed filter paper. The sample volume required is only 20 to 100 μ1 and therefore microscale analysis of the liquid sample is allowable.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300110405
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