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  • 1
    Electronic Resource
    Electronic Resource
    Determination of the enantiomeric purity of scopolamine isolated from plant extract using achiral/chiral coupled column chromatography (1991)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 5 (1991), S. 3-7 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The optical purity of scopolamine derived from Datura sanguinea was determined using coupled column chromatography. A C18 column was used to separate scopolamine from the additional alkaloids and other biological material present in the vegetal extract. The C18 column was coupled through a six-port switching valve to two β-cyclodextrin columns in series which were used to resolve the scopolamine enantiomers. A single acetylated β-cyclodextrin column gives equivalent results to the native cyclodextrin columns because of slightly higher enantioselectivity for scopolamine. A multistep extraction procedure is used to isolate scopolamine from the vegetal material. 4-6% of the scopolamine in the final extract was found to be the d enantiomer. Sample extracts as well as commercial scopolamine hydrobromide were treated under various conditions commonly encountered during typical commercial extraction procedures and analyzed in order to determine if the d enantiomer was present in the original material or if it was produced during the extraction process and, if so, determine which step and conditions contribute to acemization. Both the salt and the extract were found to be susceptible to racemization under basic conditions (≥pH 9) although the extract appeared to be more susceptible than the salt. Tropic acid formed from the hydrolysis of scopolamine seemed to be completely racemized even though the remaining scopolamine was only partially racemized. Within experimental error, no d enantiomer was found in the original fresh plant material.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130050103
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  • 2
    Electronic Resource
    Electronic Resource
    Detection of residues of chloramphenicol in crude extracts of fish and milk by tandem mass spectrometry (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 5-11 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The collision-induced dissociation mass spectrum, observed with a hybrid tandem instrument, of the ammonia chemical ionization protonated molecular ion of chloramphenicol was used for the detection of residues of the drug in biological samples. The extracted oil from fish was subjected to a rapid clean-up on a pre-packed silica gel cartridge prior to non-chromatographic tandem mass spectral analysis. Fat extracted from milk was analysed directly by on-line combined high-performance liquid chromatography/tandem mass spectrometry with rapid elution of chloramphenicol. Identification was on the basis of agreement of the daughter ion spectra obtained from sample extracts with that of the chloramphenicol standard. Detection was unambiguous at 0.5 mg kg-1. The sensitivity advantage normally expected with multiple reaction monitoring was not achieved owing to the effect of neutral noise phenomena.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180103
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  • 3
    Electronic Resource
    Electronic Resource
    Leukotriene biosynthesis: Direct chemical ionization mass spectrometry of underivatized arachidonic acid metabolites (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 509-516 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved direct chemical ionization (DCI) mass spectrometric technique, using a polyimide-coated fused silica fiber as an extended probe tip, was used to obtain molecular ions and diagnostic fragment ions of underivatized arachidonic acid, 5-hydroperoxyeicosatetraenoic acid, 15-hydroperoxyeicosatetraenoic acid, leukotriene B4 (LTB4) and, for the first time, of leukotriene A4 (LTA4)-free acid. In this technique, sample compounds are coated onto the fused silica fiber and vaporized in the plume of the reagent gas plasma of a chemical ionization source without external heating of the probe. Both ammonia and isobutane DCI spectra were obtained for each compound. A volatile alkaline eluent system was developed that allowed reversed-phase high-performance liquid chromatography of LTA4 to be followed rapidly by DCI mass spectrometry. With these techniques, the conversion of LTA4 to LTB4 during incubation with human liver microsomes was confirmed. Selected ion monitoring (SIM) of preselected ion fragments in the spectrum increases the selectivity of this technqiue and improves quantification in the range 100 ng to 10 pg.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150908
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  • 4
    Electronic Resource
    Electronic Resource
    Simultaneous detection of total and halogenated hydrocarbons in complex environmental samples (1981)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 4 (1981), S. 393-397 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, fused silica ; Simultaneous detection ; Splitting capillary effluent ; Detection limit of 1 ppm Archlor 1254 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A state-of-the-art gas chromatographic system for automatic simultaneous detection of halogenated and normal hydrocarbons has been developed, which consists of a standard Hewlett-Packard 5880 with a fused silica capillary column, whose effluent is split between the standard flame ionization detector and a Tracor Hall electroconductivity detector. The system provedes excellent capillary chromatography results and high sensitivity for halogenated compounds (a detection limit of 1 ppm Archlor 1254 in fuel oil). Reliability has been provides in the daily analysis of complex environmental samples.Emergency response cleanup and the containment of hazardous chemical spills and chemical dump sites forces one to deal with samples that are very complex. The contain large numbers of naturally occurring organic compounds and varying types of organic pollutants. Capillary chromatographic techniques of gas chromatographic and gas chromatographic/mass spectrometric analyses are necessary to achieve the resolution required for the analysis of these samples.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240040805
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  • 5
    Electronic Resource
    Electronic Resource
    Direct diagnosis of tuberculosis by computer assisted pattern recognition gas chromatographic analysis of sputum (1991)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 5 (1991), S. 165-170 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Chemical detection of tuberculosis (TB) products in sputum was attempted by using gas chromatographic analysis in conjunction with different pattern recognition computer models. For the chromatographic separations, we used a 2 mm × 1.8 m packed column and a 0.25 mm × 30 m fused silica capillary column to analyse the methylated glycosides and fatty acid methyl ester derivatives. Three computer pattern recognition methods were applied: error score, TB score and discriminant analysis. These methods predicted the presence of active TB most often in sputa of active TB patients and less so in those from inactive, suspected and non-TB patients, in that order. Although the best true positive of 75% was obtained from the TB score method and best true negative of 98% from discriminant analysis, the accompanying false positive and false negative results (36% and 50%, respectively) were unacceptable. The use of capillary column or fatty acid methyl ester derivatives of the samples did not improve on the predictive values of chromatograms obtained from the packed column on trimethylsilylglycosidic derivatives. Additional work is needed before this method can have a direct clinical application.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130050406
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  • 6
    Electronic Resource
    Electronic Resource
    The determination of meperidine, noremeperidine and deuterated analogs in blood and plasma by gas chromatography mass spectrometry selected ion monitoringAbbreviations: MBTFA = N -methyl-bis-trifluoroacetamide; TFA = trifluoroacetyl. (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1980), S. 58-60 
    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 using selected ion monitoring for meperidine and normeperidine in blood and plasma is described. Both unlabeled and [2H5]phenyl ring labeled drugs may be determined simultaneously using [2H10] analogs as internal standards. Calibration curves are linear over the range 5-100 ng ml-1, the results reproducible (coefficient of variation 〈5%), the sensitivity limit is about 5 ng using a 1 ml sample and no interference is present in blank blood or plasma, or by isotope impurity. The method is shown to be applicable to measuring the concentration of meperidine and its metabolite, normeperidine, in blood, following simultaneous administration by the intravenous and oral routes of 25 mg each of unlabeled and [2H5] labeled drug, respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200070204
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of the pesticides diflubenzuron and clofentezine in plums, strawberries and blackcurrant-based fruit drinks by high performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometry (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1441-1445 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A high performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometric (HPLC/APCI-MS) method has been developed for the determination of the pesticides diflubenzuron (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea) and clofentezine (3,6-bis(2-chlorophenyl)-1,2,4,5-tetrazine) in plums, strawberries and blackcurrant-based fruit drinks. Samples were homogenized with acetone, extracted into dichloromethane + cyclohexane and cleaned-up by high performance gel permeation chromatography. HPLC was performed on an ODS column with methanol + water at 1 mL/min. Detection was by negative-ion selected-ion monitoring APCI-MS. Comparison of response with solvent and matrix-matched standards showed some ehancement of response for the latter, and these standards were consequently used for quantification. The calibration was linear over the range 0.05-0.50 ng/μL in all three matrices. The mean overall recovery of diflubenzuron and clofentezine from spiked extracts (0.086 mg/kg) in all three matrices was 76% and 70% respectively with relative standard deviations of 15% and 12% respectively (n = 12). The limit of detection was both compound and commodity dependent and ranged from 0.01-0.05 ng/μL, equivalent to 0.003-0.014 mg/kg in the crop.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091422
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of non-volatile nitrosamines by moving belt liquid chromatography/mass spectrometry (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 616-622 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Non-volatile nitrosamines exemplified by nitroso amino acids, -dipeptides, -oxazolidines and -thiazolidines have been analysed by moving belt liquid chromatography/mass spectrometry (LC/MS) and spectra obtained by ammonia chemical ionization. Optimal conditions such as source temperature, source pressure and belt vaporizer temperature have been established. Interface degradation involving decarboxylation and denitrosation was experienced but could be alleviated to some extent by deactivation of the polyimide belt by silylation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200121009
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  • 9
    Electronic Resource
    Electronic Resource
    Electrospray mass spectrometric characterization of fluoroquinolone antibiotics: Norfloxacin, enoxacin, ciprofloxacin and ofloxacin (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 1038-1043 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We report the electrospray (ESI) mass spectra of four fluoroquinolones, enoxacin, norfloxacin, ofloxacin and ciprofloxacin, a group of highly potent antibiotics that have not been previously characterized by this ionization technique. At low sampling cone voltage settings, 50 and 100 V, the electrospray mass spectra contained primarily molecular adduct ions. At a sampling cone voltage setting of 150 V, collisionally activated dissociation mass spectra containing structurally significant product ions were produced and accurately mass measured at a magnetic sector resolution of 3000. Gradient separation and characterization of these compounds was demonstrated by analysis using packed capillary column liquid chromatography with UV and ESI-MS detection. UV detection limits in the 1 to 2 ng range ((signal-to-noise ratio S/N) = 10:1) were estimated and interpretable mass spectra with S/N ratios in excess of 100:1 were observed for 1.5 ng of analyte during electrospray mass spectrometric analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091114
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  • 10
    Electronic Resource
    Electronic Resource
    Field desorption mass spectra of methotrexate and folic acid analogs (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 245-247 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectra of methotrexate and folic acid analogs yield abundant molecular or quasimolecular ions. At emitter currents above the best anode temperature, fragment ions which are useful as further confirmations of structures are observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200030511
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