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  • Analytical Chemistry and Spectroscopy  (258)
  • Wiley-Blackwell  (258)
  • American Meteorological Society (AMS)
  • PANGAEA
  • 1990-1994  (258)
  • 1980-1984
  • 1993  (128)
  • 1990  (130)
Collection
Keywords
Publisher
  • Wiley-Blackwell  (258)
  • American Meteorological Society (AMS)
  • PANGAEA
Years
  • 1990-1994  (258)
  • 1980-1984
Year
  • 1
    Electronic Resource
    Electronic Resource
    The use of dynamically programmed scans to generate parent-ion tandem mass spectra with the ion-trap mass spectrometer (1990)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 108-113 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A method is described whereby, under software control, the scan function employed to collisionally excite ions in an ion-trap mass spectrometer is regulated so as to obtain parent ion (fixed product) tandem mass spectral data. At the same time, constant neutral-loss information is also provided. Key features are the automatic ‘intelligent’ selection of parent ions from observation of the initial mass spectrum and the scanning of the applied ‘tickle’ frequency in order to locate the precise resonance points for excitation of these ions. Results for the model compounds perfluorotributylamine (‘FC43’) and n-butylbenzene are reported and complicating effects such as the unimolecular decay of the precursor ion species and charge exchange between product ions and the original sample material are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290040404
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  • 2
    Electronic Resource
    Electronic Resource
    A detailed study of the characteristics of the ion-trap mass spectrometer using dynamically programmed scans (1990)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 415-417 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The aims of the investigation were to use the method of dynamically programmed scans to study in detail some tandem mass spectrometric characteristics of the ion-trap mass spectrometer and then to use the programs to investigate the possibility of performing benchtop gas chromatography/tandem mass spectrometry experiments on the standard instrument. In particular we have examined the effect of applying a DC ramp during the ‘tickle’ period as a means of broadening the range of resonant frequencies, thereby facilitating the tuning required to effect excitation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290041015
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  • 3
    Electronic Resource
    Electronic Resource
    Investigation of some steroids by means of thermospray and tandem mass spectrometryPaper delivered at the 11th Informal Meeting on Mass Spectromeetry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 673-675 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The detection limits of a number of steroids have been determined by means of loop-injection thermospray (TS) mass spectrometry. The measured limits were found to be in the range 1 pg-1O ng/μL. Combined positive-ion TS/tandem mass spectrometry yielded clear qualitative differences between mass selected protonatcd testosterone and estriol ions, both of which have the same nominal molecular weight. These differences are necessary for the correct identification of either species which may be present within a complex mixture. The heights of the peaks due to the two competing reaction channels, [M + H]+ and [M + NH4]+, were monitored as a function of the repeller voltage in the range 100-350 V, and the implications of the acquired data are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070725
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  • 4
    Electronic Resource
    Electronic Resource
    Mass spectrometric studies of the toxaphene components 2-exo,3-endo,5-exo,6-endo,8,8,10,10-octachloroborane (T2) and 2-exo,3-endo,5-exo,6-endo,8,8,9,10,10-nonachlorobornane (T12) (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 19-30 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron capture negative ion mass spectra of the title compounds show prominent [M - Cl]- ions, and low-abundance ions formed by further elimination of HCl or Cl2. The electron ionization positive ion mass spectra are complex, but structurally informative fragmentations are observed. In particular, fragmentations involving elimination of C2H2Cl2, and not of C2H4, C2H3Cl, C2HCl3 or C2Cl4, indicate that two chlorines are bound to the C2-C3 and C5-C6 units of a norbornane skeleton. Furthermore, from M+·, elimination of HCl is enhanced with respect to Cl·, relative to toxicants A and B, which are major components of commercial toxaphene; this result suggests that one chlorine atom is bound to each of carbons 2, 3, 5 and 6. Both compounds have CHCl2 substituents. Several of the fragmentation pathways appear to terminate at ions that may be tropylium analogues.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200220104
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of an acetylcholinesterase inhibitor, MDL 73745, in dog plasma and urine by combined gas chromatography/negative ion chemical ionization mass spectrometry (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 377-382 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly sensitive and specific assay has been developed for the determination of MDL 73745 [2,2,2-trifluoro-1-(3-trimethylsilyl-phenyl)ethanone] (I) and the internal standard (MDL 74398) at the nanomolar level in dog plasma and urine by gas chromatography/mass spectrometry. After a single-step extraction process, an aliquot was directly injected onto the gas chromatograph column. The mass spectrometer was run in the negative ion chemical ionization mode with ammonia as reagent gas, and was set to monitor the abundant M-· ion at m/z 246 of both compounds. The method yielded a linear response over the concentration range 0.1-10 pmol 100 μl-1 plasma or urine. Within-day reproducibility at a concentration of 0.25, 1 and 5 pmol 100 μl-1 plasma was 8.6%, 1.0% and 1.0%, respectively. The method was applied to the determination of I in plasma and urine after administration of 1 mg kg-1 i.v. and 10 mg kg-1 p.o. to dogs.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200220703
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  • 6
    Electronic Resource
    Electronic Resource
    Alternative driving functions for a collision quadrupole (1990)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 440-441 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The work presented here introduces a new variable parameter in the design of quadrupole collision cells. A brief summary of the mathematical theory is given to demonstrate how the maximum value of the parameter q may be altered. This is achieved through changing the driving function used for the rod potentials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290041021
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  • 7
    Electronic Resource
    Electronic Resource
    Theoretical studies of ion trajectories in quadrupole systems (1990)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 442-446 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A brief introduction to the mathematical theory of quadrupole systems is given and the configuration of hyperbolic and circular cross-section rods is considered. Application of the theory of electrostatics to the latter case indicates that multipole contributions to the field occur which influence the ion trajectories. We have considered motion in the x-z plane of a static quadrupole (DC-only) for the simplest case of a 1:1 combination of quadrupole and dodecapole contributions. The quadrupole contribution to ion motion is simple harmonic and may be described as a sine function, whereas the dodecapole contribution may only be obtained by solving the appropriate elliptic integral. This solution gives rise to a sine (amplitude) or sn function. In the case of collision cells (RF-only) we have attempted to solve the Mathieu equation both analytically and numerically. Both stable and unstable trajectories may be calculated from these solutions and are presented in various formats. Some consideration is also given to the problems of collisional interaction and the associated difficulties likely to be encountered when the study is expanded to include this phenomenon.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290041022
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  • 8
    Electronic Resource
    Electronic Resource
    Measurement of stable isotopic enrichment of underivatized acetate by gas chromatography/mass spectrometry: Application to in vivo estimation of acetate production (1990)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1990), S. 554-558 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to assess endogenous and colonic production of acetate, we have developed an assay for determining the isotopic enrichment of plasma acetate using gas chromatography/mass spectrometry (GC/MS). Acidified, deproteinized plasma (200 μl) was extracted into ethyl ether, and the ether phase was then injected into a gas chromatograph/mass spectrometer fitted with a 30 m × 0.252 mm i.d. capillary column (temperature program 50-245°C at 10°C min-1). Using electron impact GC/MS and selected ion monitoring, peak areas of ions with m/z 60 and 61 (M + 1) were determined. Triplicate extractions of enriched plasma samples (mol.% excess 1.38-1.5%) resulted in a coefficient of variation of 1.6-5.9%. Unenriched plasma samples were found to have an enrichment close to theoretical natural abundance, and analysis of our (1-13C)acetate tracer (99 at.% excess) revealed an ion at m/z 61 and no ion at m/z 60. To verify accuracy, we conducted an in vivo isotope dilution study. In a 1-month-old piglet, fasted for 24 h, changing the rate of a 4 h infusion (mmol h-1) of (1-13C)acetate from 0.141 to 0.282 doubled the isotope enrichment (2.08 x) of the second plateau. The rate of appearance of acetate was 26.0 μmol kg-1 min -1, which is comparable to that reported in fasting sheep.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200190906
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  • 9
    Electronic Resource
    Electronic Resource
    Enlarging the stability domain for ion trap tandem mass spectrometry (MS/MS) (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 215-218 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The low- mass cut-off in ion trap tandem mass spectrometry (MS/MS) is significantly improved by employing a sawtooth driving function on the ring electrode in place of the usual sinusoidal AC potential. The theory is explained with examples involving both the ‘tickle’ and ‘boundary-effect’ MS/MS methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070310
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanism of electron impact ionization-induced halogen elimination from 2-methyl-2-bromosuccinatesDedicated to Professor H. Budzikieiwcz on the occasion of his 60th birthday. (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 230-234 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact-induced halogen elimination from 2-methyl-2-bromosuccinates occurs only in the one of the two isomeric methyl ethyl esters in which the ethoxycarbonyl group is remote from the halogen, in analogy with the corresponding previously reported halosuccinates. However, the occurrence of debromination in dimethyl 2-methyl-2-bromosuccinate contrasts with the behaviour of dimethyl bromosuccinate, indicating different mechanisms for this process in the two systems. Collision-induced dissociation (CID) and deuterium labelling studies led to the conclusion that a hydrogen transfer from the 2-methyl group to a carbonyl precedes the elimination of Br· from dimethyl 2-methyl-2-bromosuccinate, resulting in a protonated dimethyl itaconate structure for the [M - Br]+ ion. An analogous process is the major route leading to [M - Br]+ ion from 1-methyl-4-ethyl 2-methyl-2-bromosuccinate. In this case deuterium labelling and CID measurements indicated a significant contribution of methyl ethyl citraconate and possibly mesaconate owing to partial operation of a mechanism similar to that reported for 1-methyl-4-ethyl 2-bromosuccinate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280315
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