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  • Analytical Chemistry and Spectroscopy  (12)
  • 1995-1999  (1)
  • 1990-1994  (11)
  • 1
    Electronic Resource
    Electronic Resource
    Liquid trapping after supercritical fluid extraction with modified carbon dioxide (1994)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 759-764 
    Details
    ISSN: 0935-6304
    Keywords: Supercrirtical fluid extraction (SFE) ; Modified carbon dioxide in SFE ; Liquid trapping ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polarity test mix consisting of acetophenone, N,N-dimethylaniline, naphthalene, 2-naphthol, and n-tetracosane was spiked onto sand and extracted with carbon dioxide modified with acetonitrile, methanol, or toluene. The extracts were collected in chloroform, hexane, methanol, or a mixed collection solvent consisting of equal parts chloroform-hexane-methanol. The mixed collection solvent which showed excellent recoveries for pure CO2, had the worst recoveries of all the collection solvents with modified CO2. Overall hexane was the best collection solvent studied for these analytes under these extraction conditions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240171106
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  • 2
    Electronic Resource
    Electronic Resource
    CGC using a programmable electronic pressure controller (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 361-365 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Electronic pressure control ; Pressure programming ; Constant flow ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary gas chromatographic separations were performed with an electronic pressure control system developed to provide precise closed-loop control of inlet pressure through the use of a solid state micro-machined pressure sensor and electronically controlled proportional valve. The closed-loop control of the electronic system provided better precision than the open-loop control achieved by manual pressure regulation. Closed-loop control can perform pressure programming, which can be combined with temperature programming to optimize separations. The pressure sensor monitors the integrity of the flow system and singals the controller to reduce flow in the presence of a sudden loss of system pressure.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240130514
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  • 3
    Electronic Resource
    Electronic Resource
    Trapping efficiencies of various collection solvents after supercritical fluid extraction (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 713-716 
    Details
    ISSN: 0935-6304
    Keywords: SFE ; Supercritical carbon dioxide ; Sand ; Test mixture ; Solvent trapping ; Solvent mixtures ; Trapping efficiency ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polarity test mix consisting of acetophenone, N, N-dimethylaniline, naphthalene, decanoic acid, 2-naphthol, and n-tetracosane was spiked onto sand, and extracted with supercritical carbon dioxide, to evaluate the collection efficiency of various solvents and solvent mixtures. Nine single collection solvent systems and four mixed collection solvent systems were studied. When one-component collection solvents were employed, quantitative (above 90%) recovery of all analytes was not possible. With mixed collection solvents, recoveries of 90% or better with all analytes studied were possible.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240161208
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  • 4
    Electronic Resource
    Electronic Resource
    Improving splitless injection with electronic pressure programming (1991)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 649-655 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Splitless injection ; Electronic pressure programming ; Reduction in discrimination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An experimental injection port has been designed for split or splitless sample introduction in capillary gas chromatography; the inlet uses electronic pressure control, in order that the column head pressure may be set from the GC keyboard, and the inlet may be used in the constant flow or constant pressure modes. Alternatively, the column head pressure may be programmed up or down during a GC run in a manner analogous to even temperature programming. Using electronic pressure control, a method was developed which used high column head pressures (high column flow rates) at the time of injection, followed by rapid reduction of the pressure to that required for optimum GC separation. In this way, high flow rates could be used at the time of splitless injection to reduce sample discrimination, while lower flow rates could be used for the separation. Using this method, up to 5 μl of a test sample could be injected in the splitless mode with no discrimination; in another experiment, 2.3 times as much sample was introduced into the column by using electronic pressure programming. Some GC peak broadening was observed in the first experiment.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240141003
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of fumonisin B1 in corn by capillary electrophoresis with fluorescence detection of the FMOC derivativePresented at the 17th International Symposium on Capillary Chromatography and Electrophoresis, Wintergreen, Virginia, May 1995 (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 7 (1995), S. 451-454 
    Details
    ISSN: 1040-7685
    Keywords: fumonisin B1 ; mycotoxin ; Fusarium moniliforme ; FMOC derivative ; capillary electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method has been developed for the analysis of fumonisin B1 in corn using capillary electrophoresis. Fumonisin B1 is the major fumonisin metabolite produced by the fungus Fusarium moniliforme and has been implicated in human and animal diseases. Fumonisin B1 was extracted from corn with acetonitrile/water (50/50) and cleaned up with a Waters C18 Sep-Pak Vac cartridge. Fumonisin B1 was quantitated after elution from the C18 Sep-Pak column using capillary electrophoresis (CE) with a 25 mM sodium borate buffer (pH 9.0) containing 10% acetonitrile and fluorescence detection of the FMOC derivative. The minimum detectable amount in corn was 0.5 ppm. Recovery values in spiked corn averaged over 96% over the range 1-20 ppm. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mcs.1220070503
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  • 6
    Electronic Resource
    Electronic Resource
    Confirmation of oxytetracycline, tetracycline and chlortetracycline residues in milk by particle beam liquid chromatography/mass spectrometryThis work was presented in part at the 38th ASMS Conference on Mass Spectrometry and Allied Topics, Tucson, Arizona, June 1990. (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1991), S. 789-795 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method using particle beam liquid chromatography/mass spectrometry was developed for the confirmation of oxytetracycline, tetracycline and chlortetracycline residues in bovine milk. This method is one of the first to apply particle beam technology to the confirmation of animal drug residues in food products for regulatory purposes. The milk is centrifuged, using molecular weight cut-off filters to remove components of 25 000 daltons and above from the milk. The filtrate is passed through a C-18 sample preparation cartridge which retains the tetracyclines. After the columns are washed with water, the tetracyclines are eluted with 0.1 M oxalic acid in methanol and concentrated. The compounds are separated on a Novapak C-18 column with a methanol-oxalic acid-acetonitrile mobile phase. Negative chemical ionization with selective ion monitoring is used to identify the tetracyclines. The procedure was used to confirm the presence of each tetracycline at 100 ng ml-1 in fortified and incurred milk samples.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200201208
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  • 7
    Electronic Resource
    Electronic Resource
    Using electronic pressure programming to reduce the decomposition of labile compounds during splitless injection (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 763-768 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Splitless injection ; Electronic pressure programming ; (EPP) ; Endrin ; DDT ; Carbaryl ; Reducing sample decomposition ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A split/splitless capillary injection port has been developed for electronic pressure programming (EPP) in gas chromatography. The inlet may be operated in several modes: constant pressure, constant flow, vacuum compensation (for gas chromatography-mass spectrometry (GC-MS)), pressure-programmed, or a combination mode enabling a pressure program to be followed by constant flow. A pressure-programming technique has been tried which uses high pressure (high column flow rate) at the time of injection followed by reduction in inlet pressure to a value required for normal chromatography. Sample is swept rapidly from the inlet and into the column, reducing contact with the hot, active inlet surfaces which cause sample decomposition. The decomposition of endrin and 4,4′-DDT, two labile pesticides, can be substantially reduced using this technique and modest improvements were also observed with the carbamate pesticide carbaryl.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240151112
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  • 8
    Electronic Resource
    Electronic Resource
    Fast atom bombardment mass spectrometry of some alkoxv- and chloro-silanes (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 81-84 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive and negative FAB mass spectra of a series of alkoxy- and chloro-silanes Xm(CH3)3-mSi(CH2)nR [m = 1 or 3, n = 3, 10 or 17, X = Cl or OMe or OEt, R = Me, NH2, glycidoxy, COOMe, NHCO(CH2)7COOMe or NHCO(CH2)10CH2OAc] were recorded in NBA and NPOE matrices. The chlorosilanes underwent rapid hydrolysis into silanols which condense to form siloxanes, the process being complete in NBA and partial in NPOE, yielding siloxane-based fragment ions in the positive spectra and silyloxyanions in the negative spectra. The alkoxysilanes were more resistant to hydrolysis, affording abundant [MH - HX]+ ions (X = OMe or OEt) in their positive FAB spectra and moderate to high intensity [M - H]- ions in the negative mode, the latter undergoing characteristic sequential loss of C2H4, EtOH and C2H4. Significant variations were observed in the positive spectra of all the silanes with change of matrix.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210260206
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  • 9
    Electronic Resource
    Electronic Resource
    Recent results using synchrotron radiation for energy-dispersive x-ray fluorescence analysis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 19 (1990), S. 53-58 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Results obtained using synchrotron radiation as an excitation source for energy-dispersive analysis are reviewed. Practical experience gained in the use of tunable, monochromatic excitation for trace analysis of various types of samples is discussed. Advantages and limitations associated with specific synchrotron radiation properties are evaluated. In particular, the influence of multiple inelastic scattering and resonant Raman scattering on limiting the degree of detectability improvements associated with energy tuning is demonstrated. A scanning x-ray microprobe employing multilayer mirrors as focusing elements is described. Measurements performed with this system have demonstrated the capability of detecting femtogram quantities of trace elements in a 10 × 10 μm area.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300190205
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  • 10
    Electronic Resource
    Electronic Resource
    XRS analysis of sulphides by fusion methods (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 19 (1990), S. 67-71 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A method is described for the XRS fusion analysis of mineral and plant concentrates containing sulphides (e.g. PbS, ZnS, CuFeS2 and FeS2) together with slags, mattes, fumes and drosses. The method involves a short pre-oxidation treatment using sodium nitrate, followed by fusion with an appropriate heat source. Losses of S by volatilization and of metals into the platinum crucibles are acceptably small for general assay purposes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300190208
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