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  • Analytical Chemistry and Spectroscopy  (9)
  • 1
    Electronic Resource
    Electronic Resource
    Synthetic pyrethroid insecticides analysis by gas chromatography/mass spectrometry operated in negative-ion chemical ionization mode in soil, moss and fish tissue (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1411-1417 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A gas chromatographic/mass spectrometric method was developed for the simultaneous determination of five synthetic pyrethroid insecticides in soil, moss and fish tissue. These pyrethroids were extracted with hexane-dichloromethane by ultrasonication and cleaned up on Florisil (soil and moss) and mixed acid/base alumina (fish) columns prior to determination by gas chromatography/negative-ion chemical ionization mass spectrometry in selected ion monitoring mode. All the pyrethroids were analyzed simultaneously in a single run on a DB5-MS 15 m capillary column. Recoveries of the pyrethroids from the three matrices at fortification levels of 10, 50 and 100 μg/kg ranged from 80 to 117%. Four determinations were made at each concentration level for each matrix. The practical determination limit of the method was in the range 0.5 to 5 μg/kg depending on the compound. This method was also applied to samples obtained from a contaminated ecosystem.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091418
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  • 2
    Electronic Resource
    Electronic Resource
    Bis(trifluoromethyl)aryl derivatives for drug analysis by gas chromatography electron capture negative ion chemical ionization mass spectrometry. Application to the measurement of low levels of clondine in plasma (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 435-440 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic mass spectrometric assay for clonidine in plasma with a detection limit of a few picograms per ml was required. The p-trifluoromethylbenzyl, pentafluorobenzyl and pentafluorobenzoyl derivatives of clonidine were synthesized and the electron capture negative ion chemical ionization mass spectra of these compounds show extensive fragmentation with prominent ions at m/z 35 and 37 due to the two chlorine atoms in the clonidine molecule. Selected ion monitoring of specific high mass ions in these mass spectra indicated that the required sensitivity could not be obtained with these derivatives. Several bis(trifluoromethyl)pyrimidines were synthesized and these compounds were found to give an intense negative ion current under conditions of resonance electron capture. Consequently, a derivative of clonidine containing a bis(trifluoromethyl)aryl group was synthesized by reacting the drug with 3,5-bis(trifluoromethyl)benzoyl chloride. The negative ion mass spectrum of the reaction product has a base peak at m/z 673 and, when this ion is specifically monitored, an amount of derivative equivalent to 1 picogram of clonidine can be detected. This allowed the development of an assay for clonidine in plasma with a precision of 8% (SD) at 50 pg ml-1, 22% (SD) at 20 pg ml-1 and a lower limit for quantitative determination of 10 pg ml-1. Plasma concentrations of clonidine In 10 subjects given a single 50μg oral dose are reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200110813
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  • 3
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance spectroscopy, by Ruth M. Lynden-Bell and Robin K. Harris. Thomas Nelson and Sons Ltd, London. 1969. 160 pp. + viii. £1.15.0. (paperback) (1970)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 2 (1970), S. 225-226 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270020216
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  • 4
    Electronic Resource
    Electronic Resource
    An assay for 2-amino-3,8-dimethylimidazo[4,5-ƒ]-quinoxaline and 2-amino-3,4,8-trimethylimidazo-[4,5-ƒ]quinoxaline in fried beef using capillary column gas chromatography electron capture negative Ion chemical ionization mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 221-224 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic/mass spectormetric assay has been developed for the simultaneous measurement of 2-amino-3,8-dimethylimidazo[4,5-ƒ]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-ƒ]quinoxaline (DiMeIQx) in fried beef. The method employs capillary column gas chromatography, electron capture negative ion chemical ionization mass spectrometry and a stable isotope labelled analogue of MeIQx as common internal standard. Two patties of lean minced beef which had been cooked separately were analysed and found to contain both compounds (patty 1:2.4 ng MeIQx g-1 meat, 1.2 ng DiMeIQx g-1 meat; patty 2: 1.3 ng MeIQx g-1 meat, 0.5 ng DiMeIQx g-1 meat). Neither compound was present in the meat prior to cooking.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160140
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  • 5
    Electronic Resource
    Electronic Resource
    Letter to the editors (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1980), S. 183-183 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200070410
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  • 6
    Electronic Resource
    Electronic Resource
    The measurement of clonidine in human plasma and urine by combined gas chromatography mass spectrometry with ammonia chemical ionization (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 500-502 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimethyl derivatives of clonidine and [2H4]clonidine give good chemical ionization mass spectra when ammonia is used as reagent gas. A gas chromatographic mass spectrometric selected ion monitoring assay for the estimation of clonidine in plasma and urine using ammonia chemical ionization is described.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200081007
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  • 7
    Electronic Resource
    Electronic Resource
    Bistrifluoromethylaryl derivatives for drug analysis by gas chromatography electron capture negative ion chemical ionization mass spectrometry. Application to the measurement of (N-dicyclopropylmethyl)amino-2-oxazoline in plasma (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 230-237 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic mass spectrometric assay for (N-dicyclopropylmethyl)amino-2-oxazoline in plasma with a detection limit of 0.1 ng ml-1 was required. Various fluoroaryl derivatives of this compound (code name S3341) were synthesized and their positive ion chemical ionization and electron capture negative ion chemical ionization mass spectra recorded. While fluorobenzyl derivatives of S3341 could be made by heating with the requisite benzyl bromide and diisopropylethylamine in acetonitrile, initial efforts to synthesize corresponding fluorobenzoyl derivatives using a benzoyl chloride in dry ethyl acetate at 60 °C were unsuccessful. Mass spectral data indicated that only a fragment of the oxazoline ring was retained in the reaction product and that an N-(2-chloroethyl)benzamide was formed. However, when diisopropylethylamine was included in the reaction mixture, a benzoyl derivative of the complete molecule was obtained. The mechanisms of these reactions are discussed. The negative ion mass spectrum of the 3,5-bistrifluoromethylbenzoyl derivative of S3341 has a base peak at m/z 420 (the molecular ion) and, when this ion is specifically monitored, an amount of derivative equivalent to 1 pg of S3341 can be detected. This allowed the development of an assay for S3341 in plasma with a precision of 9% (SD) at 0.2 ng ml-1 and a lower limit for quantitative determination of 0.1 ng ml-1.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200120509
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  • 8
    Electronic Resource
    Electronic Resource
    Temperature dependence of NMR secondary references for D2O and (CD3)2SO solutions (1988)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 523-525 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR secondary references ; 13C NMR secondary references ; Temperature dependence ; D2O solutions ; (CD3)2SO solutions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical shifts of secondary references for D2O and (CD3)2SO solutions were measured as a function of temperature. The 1H and 13C chemical shifts of dioxane, sodium 4,4-dimethyl-4-silapentanesulphonate, HOD, tetramethylammonium chloride and sodium 3-(trimethylsilyl)propionate-d4 in D2O solution were measured relative to external TMS and the chemical shifts of (CD3)2SO and H2O were measured in (CD3)2SO solution relative to internal TMS. For accurate comparison of chemical shifts it is necessary to take into account the sample temperature and, therefore, the temperature dependences of 1H and 13C chemical shifts of a number of secondary references have been determined accurately and fitted to a parabola or straight line, as appropriate.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260260617
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  • 9
    Electronic Resource
    Electronic Resource
    1H and 13C NMR assignment of maltitol by a combination of 2D NMR and H/D isotope effects on nuclear shielding (1988)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 425-429 
    Details
    ISSN: 0749-1581
    Keywords: Maltitol ; 13C NMR assignment ; 2D-INADEQUATE ; SIMPLE NMR ; DIS NMR ; 1H NMR assignment ; 1H-13C COSY NMR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Maltitol was assigned unequivocally without any need for reference to model compounds by a combination of 2D, SIMPLE (secondary isotope multiplets of partially labelled entities) and DIS (differential isotope shift) NMR techniques. The combination of these three techniques is very powerful for the assignment of molecules with many exchangeable hydrogen atoms, such as carbohydrates. In the case of maltitol a complete 13C NMR assignment was achieved in three solvents [H2O, D2O and (CD3)2SO] using three experiments. A 1H-13C 2D correlation experiment allowed the 1H NMR spectrum to be assigned unequivocally for the first time.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260260514
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