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  • 1980-1984  (4,319)
  • Analytical Chemistry and Spectroscopy  (4,318)
  • Nuclear reactions
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984), S. 1-37 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984), S. 153-154 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984), S. 155-155 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984) 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984), S. 591-593 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984), S. 587-587 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984) 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 1-3 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple, high throughput method of analysis of trimethylamine in body fluids has been developed to assist with the management of patients with the inherited metabolic disorder, trimethylaminuria. The headspace in sealed vials was analysed using perdeuterated (2H10)trimethylamine hydrochloride as an internal standard. The gas chromatograph inlet system of the mass spectrometer was adapted to suit this method of analysis. Medium resolving power was used to measure the ion ratio of the [M-H]+ ion of trimethylamine and the [M-2H]+ ion of the internal standard. The method is faster and more accurate than gas chromatographic methods. The concentrations of trimethylamine found in normal urine are similar to those reported previously.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 4-9 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct analysis of underivatized steroid and vitamin D glucuronide and sulfate conjugates by positive and negative ion fast atom bombardment mass spectrometry has been demonstrated. The technique allows unambiguous molecular weight determination of these conjugates and provides useful fragmentation information in many cases. Analysis of low microgram amounts of such conjugates purified from biological sources has been carried out.
    Additional Material: 8 Ill.
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  • 10
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Positive ion and negative ion fast atom bombardment mass spectra of several natural and synthetic enzyme inhibitors are presented. It is shown that the fast atom bombardment method is well suited to the analysis of these unusual peptides. Complete amino acid sequences can be deduced from the mass spectra in most cases. Structural features typical of the inhibitors include (a) C-terminal aldehyde groups (e.g. leupeptin), (b) urea linkages in the peptide backbone (e.g. antipain, chymostatin), (c) prevalence of arginyl or α-(2-iminohexahydropyrimidyl)glycl residues, and (d) presence of an N-(glycosylphosphoryl) group (e.g. phosphoramidon). Several examples of synthetic peptides with common protecting groups are also presented. It is concluded that positive ion and negative ion fast atom bombardment mass spectra provide complementary information, the two techniques being sensitive to entirely different structural aspects of the inhibitors.
    Additional Material: 5 Ill.
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  • 11
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantification of 2-ketoglutaric acid in plasma and cerebrospinal fluid as its O-trimethylsilyl-quinoxalinol derivative by gas chromatography chemical ionization mass spectrometry is described with benzoylformic acid as internal standard. This technique, with ammonia as reactant gas, only detects the protonated molecular ions. The recovery of 2-ketoglutarate from perchloric-deproteinized plasmas is 99.7±1.2%. The normal value of 2-ketoglutarate in children is 8.6±2.6 μmol I-1 (Mean ± standard deviation) in plasma (n =25) and 4.8±1.4 μmol I-1 in cerebrospinal fluid (n 20). The plasma level of 2-ketoglutarte is correlated with urea concentration (r = 0.96; p 〈 0.001) in healthy subjects and in patients with chronic renal insufficiency. Increased values are found in one case of pyruvate carboxylase deficiency, and inconstantly in diabetes; physiological variations are described during tasting and after an oral glucose load.
    Additional Material: 3 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 41-46 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive and negative fast atom bombardment spectra of two nucleosides, 10 mononucleotides, two derivatized mononucleotides and 11 dinucleoside monophosphates have been recorded. Molecular ions (protonated or deprotonated) and some structurally significant fragments, sometimes involving cationization, were obtained. The spectra were compared with field desorption and thermospray ionization spectra whenever possible.
    Additional Material: 5 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 35-40 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectral data relative to 38 anthracycline derivatives are presented. A molecular ion, or [MH]+ ion is always present; in most cases it is the base peak in the spectrum at the best anode temperature. Increase in the emitter temperature promotes fragmentation which gives useful structural information. A comparison has been made between field desorption and other soft ionization techniques such as fast atom bombardment, desorption chemical ionization and a liquid chromatographic mass spectrometric interface with direct liquid introduction into a chemical ionization ion source. The most significant results were obtained by using positive and negative ion fast atom bombardment and direct liquid introduction with negative ion detection.
    Additional Material: 5 Ill.
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  • 14
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Betaxolol, a beta selective adrenoceptor antagonist recently approved for the treatment of hypertension, was determined by monitoring in chemical ionization mode with ammonia the [MH]+ ions of the trimethylsilyl derivatives of the drug and of its internal standard ((2H5)betaxolol). Its pharmacokinetic profile obtained following administration of a 20 mg oral dose was characterized by a half-life of 22 h and a bioavailability of 85%. The main acid metabolite formed by elimination of the isopropylamino group may also be determined as the methyl TMS derivative but methylation with BF3-methanol should be used with caution since it may induce the opening of the cyclopropyl group. The routine electron capture determination procedure was compared to this mass spectrometric method and an excellent correlation was found (r = 0.9974). Both procedures have the same sensitivity (1 ng ml-1). Finally it was observed that under electron impact mode betaxolol trimethylsilyl side chain rearranged to lose TMS—O—CH=CH2; this elimination was confirmed by deuterium labelling studies.
    Additional Material: 7 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 47-49 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Platelet activating factor has recently been structurally described as the phospholipid 1-O-alkyl-2-O-acetyl-sn-glycerophosphocholine. It has been reported to be a putative chemical mediator of immunological reactions as well as an antihypertensive agent. A method to quantitate 1-O-alkyl-2-O-acetyl-sn-glycerophosphocholine using deuterium labeled 1-O-alkyl-2-O-acetyl-sn-glycerophosphocholine as an internal standard is described. When 60 ng of the2H3 labeled compound is employed, quantities as low as 10 ng can be measured. The standard curve for this quantitative analysis typically had a correlation coefficient of 0.999 even when the signal saturation effect of FAB was apparent. Thus quantitative analysis using the FAB ionization technique is feasible when one employs the stable isotope internal standard method.
    Additional Material: 3 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984) 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 142-144 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The development of an analytical method for the determination of brain tryptamine using capillary gas chromatography mass spectrometry (selected ion monitoring) is presented. The method involves solvent extraction of brain homogenates and further derivatization (pentafluoropropionyl derivatives) of the dried extracts. Gas chrmatographic analysis is performed using a bonded phase silica fused capillary column. Selected monitoring of M/z 289 and 292 (isotope dilution technique) allows the determination of tryptamine in adult rat brain (450 ± 73 pg g-1) (X ± SEM), n = 6.
    Additional Material: 1 Ill.
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  • 18
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acylcarnitines, a biologically important group of metabolites which have thus far eluded characterization by mass spectrometry, exhibit very intense fast atom bombardment mass spectra dominated by parent cations. The combination of high resolution selected ion detection and daughter ion analysis using the linked scan at constant B/E ratio has enabled the unequivocal identification of the acylcarnitines in the urine of children with propionic acidemia, methylmalonic aciduria and Reye's Syndrome. Quantitative analysis of acetylcarnitine and propionylcarnitine in selected samples was accomplished by isotope dilution, utilizing (2H3)acetyl- and (2H5)propionylcarnitines as internal standards. These techniques will allow assessment of the therapeutic use of L-carnitine in these disorders.
    Additional Material: 5 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 450-454 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five benzothiazole derivatives leached into injections by the rubber plunger-seals of disposable syringes were identified by electron impact (EI) and chemical ionization (CI) mass spectrometry. These are 2-hydroxybenzothiazole, 2-mercaptobenzothiazole, 2-(methylmercaptopto)benzothiazole, 2-(2-hydroxyethoxy)benzothiazole and 2-(2-hydroxyethylmercapto)benzothiazole. 2-Mercaptobenzothiazole is used as a vulcanization accelerator. The other four compounds are formed from the zinc derivative of 2-mercaptobenzothiazole during sterilization with ethylene oxide. Toxicological, technological and legal consequences of the leaching are discussed briefly.
    Additional Material: 2 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 462-465 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive and efficient analytical procedure was developed to determine phenobarbital-N-glucoside, phenobarbital and p-hydroxyphenobarbital in urine. The stable-isotope labeled internal standards used in this assay were obtained in urine from a subject who ingested 15N-labeled phenobarbital.
    Additional Material: 3 Ill.
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  • 21
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amiodarone is an antiarrhythmic drug which has received considerable attention in recent years. It has been suggested that the unusual pharmacodynamic characteristics of this drug may be due in part to the influence of active metabolites. Using fast atom bombardment (FAB) mass spectrometry we have identified a new metabolite of amiodarone, the di-N-desethyl analog (DDEA). This metabolite was present in the blood of dogs treated with the parent drug, and showed a greater affinity for myocardium than did the parent drug. The unique features of FAB mass spectrometry over electron impact mass spectrometry was an essential element in facilitating the identification of this new metabolite. Whether or not this metabolite has pharmacologic activity or is responsible for some of the side effects occurring during amiodarone administration is not known.
    Additional Material: 6 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 472-474 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C/12C ratios of the carboxyl and methyl carbons of acetic acid were determined by two published methods, using the thermal decomposition of sodium acetate and calcium acetate respectively. Comparison of the results obtained on a variety of samples revealed a systematic disagreement of 4.0% between the two methods. The source of this discrepancy is shown to be a fractionation associated with the calcium acetate method.
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  • 23
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for the determination of flutroline in plasma using capillary gas chromatography and selected ion monitoring detection of the TMS derivative. The method is linear over the concentration range of 3-60 ng ml-1 and was used to define the drug pharmacokinetics and bioavailability in animals and man. A novel method for direct derivatization on the tip of a moving needle injector is described.
    Additional Material: 2 Ill.
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  • 24
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 475-481 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The desorption ionization mass spectra are reported for two classes of synthetic porphyrins - ‘tailed’ derivatives of deuteroporphyrin IX and meso-substituted derivatized tetraphenylporphines. The mass spectra were obtained by three desorption ionization techniques - fast atom bombardment (FAB), desorption chemical ionization (DCI) and ‘in-beam’ or desorption electron ionization (DEI). The emphasis of this study is to determine the usefulness of the three desorption ionization methods for the molecular weight and side-chain structure determinations of synthetic porphyrins. The molecular parent ions and the major fragmentation pathways are discussed in detail. The DEI method yielded the fewest mass spectra showing molecular parent ions from the compounds studied, whereas FAB gave the most. The major fragmentation pathways were compound dependent and similar for all three ionization methods; generally, those cleavages α and β to carbonyl groups predominated. The FAB spectra showed strong molecular adduct ions in several spectra that could be attributed to an in situ coordination of iron-containing porphyrins with the thio-containing liquid matrix molecules.
    Additional Material: 2 Ill.
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  • 25
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 26
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 493-493 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 27
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Curiepoint pyrolysis (Py)-mass spectrometry (14 eV electron impact) in various modes of operation and Curiepoint pyrolysis-gas chromatograpy/mass spectrometry (Py-GC/MS) afforded discrimination between homopolyhexoses of different glycosidic linkage type and configuration: (1 → 2)-β-, (1 → 3)-β-, (1 → 4)-α-, (1 → 4)-β-, (1 → 6)-α, (1 → 6)-β-glucan and (1 → 2)-α-mannan. Pyrolysis-mass spectrometry in multichannel averaging mode, combined with discriminant analysis data processing, revealed significant discrimination between all polyhexoses, except for the (1→6) linked polymers. By using preheated telescopic glass tube sample holders, additional specificity of the pyrolysis-mass spectral fingerprint for the (1 → 3) linked carbohydrate was obtained. Pyrolysis-mass spectrometry in time-resolved mode yielded ion profiles, especially characteristic for the (1 → 3)-β-glucan. Py-GC/MS was an additional discriminating dimension (retention time), providing structural information about the pyrolysate constituents, in particular concerning the anhydrohexoses.
    Additional Material: 5 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 494-494 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 29
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984) 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 30
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 529-534 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in-beam electron ionization (EI) spectra of quaternary ammonium salts of dextromethorphan and piperidine consist of peaks arising both from thermal degradation products and from the fragmentation of the molecular cation [R4N]+. Mass-analysed ion kinetic energy and ion kinetic energy spectra indicate that several major ions believed to be thermally induced before EI are also produced directly from [R4N]+ fragmentation. However, the contribution of the direct fragmentation of [R4N]+ upon EI is small in comparison to that of the thermal degradation products. This behavior was observed in the conformationally flexible and rigid piperidinium rings studied.
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  • 31
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 545-548 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eleven mass spectrometers all connected with a gas chromatograph were used for quantitative determination by the isotopic dilution technique. The purpose of the investigation was to compare the virtual performances of the instruments rather than the routines of the individual laboratories. Therefore, calibration compounds and samples were distributed to the participants. A satisfactory linearity but poor reproducibility was found.
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  • 32
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 539-544 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a number of N-acyl-5-aminosalicylic acids and their derivatives is described. These compounds allow the sensitive and specific mass spectrometric determination of unlabelled or deuterium-labelled N-acetyl-5-aminosalicylic acid in biological samples. An in vivo study shows that the labelled compound, administered to rats, is excreted isotopically unchanged to at least 97%, and that no significant deacety lation/acetylation mechanism exists for this metabolite N-acetyl-5-aminosalicylic acid of salicylazosulphapyridine.
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  • 33
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 583-588 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In recent years stable isotopes have begun to replace radioisotopes as tracers in metabolic studies. However, these are relatively expensive in the enrichments and quantities required by either conventional gas chromatography/mass spectrometry (GC/MS) or stable isotope ratio analysis (SIRA), the former having good sensitivity but low precision and the latter low sensitivity with more than adequate precision. We describe here a technique for 13C which achieves an appropriate balance between precision and sensitivity for such studies. A combustion interface is placed between the output from a capillary gas chromatograph and a dual collector SIRA mass spectrometer. Compounds eluting from the gas chromatograph are converted into discrete pulses of CO2 gas and intensities of 13CO2 and 12CO2 are measured simultaneously. Typically, 13C relative abundances can be obtained from 0.8 nmol of a C10 compound (8 nmol CO2) with a precision (1SD) of better than 1‰ (0.0011 at.%13C). This permits a reduction by at least a factor of 10 in the quantity of tracer required compared with conventional methods.
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  • 34
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 594-600 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of metabolites of trinitrotoluene (TNT) have been synthesized and analysed by electron impact (EI) and chemical ionization (CI) mass spectrometry. Identification characteristics of these metabolites by their mass spectra have been determined. Differentiation of isomers is made possible by EI ions which are characteristic of the position of the methyl group with regard to the nitro groups.
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  • 35
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Specific and sensitive procedures have been developed which enabled the structure elucidation of the polypeptide antibiotics (peptaibols), paracelsin isolated from Trichoderma reesei, and of trichotoxin A-50 from Trichoderma viride, by fast atom bombardment and field desorption mass spectrometry. Both peptides were found to exhibit a pronounced microheterogeneity by single and multiple exchange of amino acids. Separation by analytical and semipreparative high-performance liquid chromatography (HPLC) on octadecylsilyl-bonded, reversed-phase columns afforded a series of sequence analogues for each polypeptide. Unequivocal molecular weight and sequence identifications were obtained by positive and negative ion fast atom bombardment (FAB), and field desorption (FD) mass spectrometry, in combination with a single, selective acidolytic cleavage step. Most important for the FAB mass spectral analysis of the extremely hydrophobic polypeptides was the development of oligoethylene-glycols and -glycol ethers as suitable liquid matrix systems, yielding high sensitivity and structurally significant fragment ions of high abundance. At these conditions, the positive ion FAB mass spectra exhibit regular abundant sequence ions with acylium end groups by peptide bond cleavage from the N-terminus, which provided direct sequence determinations for 13 of 20 residues of paracelsin, and for 12 of 18 residues of trichotoxin A-50. The sequence-specific fragmentation precisely continues up to, and ends at the preferential acidolytic cleavage sites (Pro residues). The remaining C-terminal sequence data was obtained by FD and FAB mass spectra of prolyl-hexa- and -heptapeptaibols produced by acidolytic cleavage in situ with aqueous trifluoroacetic acid. In contrast to the original polypeptides, glycerol as a polar matrix was most suitable for the analysis of prolylpeptaibol fragments in the hyrolysis mixture. By contrast, treatment of paracelsins and trichotoxins A-50 with trifluororacetic acid under anhydrous conditions yielded the corresponding trifluoroacetylated polypeptide derivatives which served to ascertain the position of the C-terminal amino alcohol residues. With this procedure, the structures of 14 closely related, partially isobaric sequence analogues of trichotoxin A-50, and of four sequence analogues of paracelsin were determined with amounts of material in the low nanomole range, which provide an exact pattern of the variable and the conservative sequence areas for these polypeptides.
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  • 36
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    Biological Mass Spectrometry 11 (1984), S. 601-601 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 37
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    Biological Mass Spectrometry 11 (1984), S. 611-615 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diphenylborinic acid is shown to react with a variety of polyfunctional molecules of biological interest to give products which are easily identifiable by mass spectrometry. The diphenylborinate adducts of amino acids possess extraordinary stability and are separable by reverse phase chromatography. The stability of products is discussed with regard to the nature and stereochemical arrangement of the functional groups involved in complex formation.
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  • 38
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of antimalarials by high-performance liquid chromatography (HPLC)/mass spectrometry demonstrates a new dimension in specificity along with increased sensitivity compared to conventional HPLC detection methods. Both direct liquid introduction and thermospray HPLC/mass spectrometry interfaces provided molecular weight information as well as characteristic fragment ions for antimalarials not normally amenable to direct probe or gas chromatographic/mass spectrometric techniques. The direct liquid introduction interface, which incorporated a 1/100 split, showed a detection limit of 30 ng using selected ion monitoring. The thermospray technique showed less than 1 ng detection limits using selected ion monitoring.
    Additional Material: 8 Ill.
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  • 39
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The presence of the nucleoside antitumor antibiotic toyocamycin in the fermentation broth was determined by a combination of negative and positive ion fast atom bombardment (FAB) mass spectrometry, high resolution FAB mass spectrometry and mass-analysed ion kinetic energy spectrometry (MIKES). A reasonable limit of detection for toyocamycin in the whole broth was obtained by combining the specificity of mass spectrometry/mass spectrometry (also called tandem mass spectrometry) to FAB. The role played by the fermentation matrix upon the production and the observation of characteristic ions by FAB. using xenon atoms was examined. High-performance liquid chromatography (HPLC) and FAB mass spectrometry were used to monitor toyocamycin at all stages of strain development, fermentation and recovery.
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  • 40
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    Biological Mass Spectrometry 11 (1984), S. 629-632 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical method to determine the concentration of bupropion in human plasma has been developed using a deuterium-labeled analog as internal standard and selected ion monitoring applied to an extract of plasma samples taken as part of a clinical trial of this antidepressant. In all, 15 depressed outpatients were randomly assigned to bupropion in a double-blind study which included weekly evaluation of their clinical condition. A good correlation was found between the results obtained by this assay and by a radioimmunoassay technique currently in use. While no simple correlation between plasma concentration and therapeutic improvement was noted, the majority of subjects showed mild to marked amelioration of symptoms and those having mean concentrations above 35 ng ml-1 had significant improvement in their test scores. Interpretation of the mass spectra of both the labeled and unlabeled drug revealed an apparent violation of the ‘even-electron rule’.
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  • 41
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    Biological Mass Spectrometry 11 (1984), S. 633-642 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This report describes the use of direct chemical ionization mass spectrometry with ammonia as the reagent gas (NH3-DCI) for structure analysis of underivatized, permethylated and permethylated and reduced glycosphingolipids. In contrast to ionization by electron impact the NH3-DCI mass spectra exhibit intense molecular and carbohydrate sequence-related ions using microgram amounts of sample. Underivatized glycosphingolipids with up to two sugar residues yield abundant protonated and ammonia-cationized molecular ions and structurally significant fragments. Permethylation in conjunction with NH3-DCI can be used to obtain molecular weight as well as oligosaccharide sequence and branching information on neutral, acidic and complex-type glycosphingolipids with up to five sugar residues. Reduction of the permethylated derivatives gives rise to several new, structurally significant fragments in the corresponding NH3-DCI mass spectra which enable fatty acid and base compositions to be determined. Isotopically labeled reagent gases have been used to confirm the assignment of fragment structures and to demonstrate that the ions observed are unique to the NH3-DCI mass spectra.
    Additional Material: 5 Ill.
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  • 42
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 10 Ill.
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  • 43
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    Mass Spectrometry Reviews 3 (1984), S. 395-438 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 23 Ill.
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  • 44
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    Mass Spectrometry Reviews 3 (1984), S. 231-315 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 42 Ill.
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  • 45
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    Mass Spectrometry Reviews 3 (1984), S. 317-318 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 46
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    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 3 (1984) 
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 47
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    Biological Mass Spectrometry 11 (1984), S. 60-62 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aspects of quantitative analysis using fast atom bombardment mass spectrometry were investigated for several compounds of biological interest. Internal standards of two types were employed; the structural analog dansyl-asparagine for the quantitation of dansyl-glutamine and stable isotopically labeled 4-amino-(2,2-2H2)butyric acid for the quantitation of 4-aminobutyric acid. Widely varying concentration ranges, from 0.5 to 250 nmol μl-1, were measured to establish the dynamic range of the measurements. The results showed that at analyte concentrations below 10-20 nmol μl-1, the abundance of the analyte's quasi-molecular ion is proportional to concentration while the abundance of that of the internal standard is relatively constant. At higher concentrations of analyte, the abundance of the [M + H]+ of the internal standard decreases while that for the analyte increases, with both of these effects diminishing as the surface of the sample becomes saturated with analyte. Nevertheless, the standard curve produced from plotting the abundance of the [M + H]+ of the analyte (relative to that of the internal standard) versus the amount of analyte gives a straight line.
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  • 48
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    Biological Mass Spectrometry 11 (1984), S. 75-78 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methane chemical ionization (CI) gas chromatography mass spectrometry (GCMS) has been used to study choline chloride esters of 16C, 17C and 18C fatty acids and the β-acetoxy derivative of palmitylcholine chloride (Pahutoxin). All choline esters recorded [M—CH3CI]+ as their highest mass ion and m/z 72 [CH2—CH2—N+(CH3)2] as the base peak. Transmethyiation generated the methyl esters of the 16C-18C fatty acids and in the case of the β-acetoxy derivative of the 16C choline ester chloride the α:β -unsaturated 16C methyl ester was the major product. Mild hydrolysis of β-acetoxypalmitylcholine chloride yielded β-acetoxypalmitic acid.
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  • 49
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    Biological Mass Spectrometry 11 (1984), S. 79-86 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mycobacteria synthesize a variety of unusual long-chain fatty acid esters and the systematic analysis of these is of great potential in the classification and identification of these bacteria. This paper describes the extraction, reductive fission and derivatization to tert-butyldimethylsilyl ethers of β-diesters, the phthiocerol dimycocerosates. The mass spectra of these ethers are characteristic of the parent alcohols and selected ion monitoring techniques have been applied to mixtures extracted from strains of Mycobacterium tuberculosis.
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  • 50
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    Biological Mass Spectrometry 11 (1984), S. 87-95 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using mono-, di-, tri- and tetrasaccharides, nucleosides, bile acids, riboflavin, gibberellin A3, aminoglycosides, flavanoid and cardenolide glycosides, the sodium salt of riboflavin phosphate and the quaternary ammonium drug propantheline bromide, the performance of a new moving belt interface for liquid chromatography mass spectrometry has been evaluated. It is shown to be superior to previous interfaces of this type in its ability to provide relative molecular mass information from thermally labile low volatility compounds. The spech a obtained are similar to those obtained by desorption chemical ionization.
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  • 51
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lysophosphatidic acids having diferent fatty acyl moieties were directly analysed by gas chromatography/mass spectrometry after silylation. Trimethylsilyl derivatives of various LPAs escaped thermal degradation, and electron impact and chemical ionization of these derivatives yielded many ions which were useful for the structural determination. It was found by this new method that five species of lysophosphatidic acids were formed in rat plasma during incubation at 37°C.
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  • 52
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method based on direct exposure, positive ion, chemical ionization mass spectrometry/mass spectrometry (ms/ms) was developed for the confirmatory assay of the antiparasitic drug, ivermectin, in animal tissue. Following extraction, column and preparative liquid chromatography, mass spectrometric/mass spectrometric analysis of the drug in liver samples provided reliable detection limits to 8-10 parts-par-billion at a signal: noise of greater than 10:1. Blank tissue consistently displayed no chemical/matrix interference. Besides the development of a confirmatory assay, the study also demonstrates the analytical capabaility and the role of MS/MS vis-a-vis other applied mass spectrometric techniques.
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  • 53
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    Biological Mass Spectrometry 11 (1984), S. 182-186 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass measurements of the protonated molecules [M + H]+ of four insulins are presented. In addition, structurally significant fragment ions are observed in the mass spectrum and metastable scanning has been used to link these ions to the protonated molecule.
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  • 54
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    Biological Mass Spectrometry 11 (1984), S. 177-181 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study reports a rearrangement process observed in electron capture negative ion chemical ionization mass spectrometry of pentafluoropropionate and heptafluorobutyrate derivatives of some β-hydroxylated amines. The pentafluoropropionate derivatives of a number of these substituted amines yield a prominent anion of mass 145 (195 in the corresponding heptafluorobutyrate derivatives). In the pentafluoropropionate derivatives of ethanolamine and β-hydroxyphenethylamine this anion was quantitatively displaced to m/z 146 when the γ-hydrogen (relative to the derivatized hydroxyl group) was substituted by deuterium. We postulate an initial 6-membered transition state to produce a pentafluoropropionic acid anion (not observed) which then eliminates either a hydrogen atom to give m/z 163 or a fluorine atom to give m/z 145. The former remains at mass 163 in the γ-deuterated compounds examined. The proposed rearrangement is the negative ion analogue of the McLafferty rearrangement process of positive ion electron impact mass spectrometry. However, the negative ion rearrangement is not as general as its positive ion electron impact counterpart because the former is critically dependent upon the substitution present on the α and β carbon and nitrogen atoms, respectively, of the β-hydroxyamine-PFP (or HFB) derivatives. In this regard we examined the effects on m/z 145 anion formation of methyl substitution on the nitrogen and α and β carbon atoms of these pentafluoropropionate derivatives. The results suggest that electron capture methane negative ion chemical ionization mass spectra of β-hydroxylated PFP derivatives could be used as diagnostic tool for structural assignments within this group of compounds.
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  • 55
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    Biological Mass Spectrometry 11 (1984), S. 187-192 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Picolinyl esters of cyclopropane fatty acids produced characteristic mass spectra which enabled differentiation from isomeric monounsaturated acids by the presence of an abundant ion produced by formal cleavage through the cyclopropane ring. The mass of this ion indicated the position of the cyclopropane ring on the aliphatic chain and it could be identified by its odd mass and its separation of 13 mass units from ions in adjacent groups. Other major fragment ions arising from radical-induced cleavage of the chain following random hydrogen abstraction showed a 14 mass unit separation. This characteristic feature was also found in the mass spectra of bis-cyclopropane acids where each ring produced a characteristic ion of odd mass. Other features serving to differentiate cyclopropane acids from unsaturated acids were the abundant [M-1]+ ions and the presence of an ion at m/z 133. The nicotinyl derivatives of the corresponding cyclopropane alcohols showed analogous fragmentations. Mechanisms for the formation of the diagnostic ions are suggested.
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  • 56
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    Biological Mass Spectrometry 11 (1984), S. 199-201 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A prominent plasma metabolite was detected in animals and man after oral administration of 5-(2-bromo-E-ethenyl)-2′-deoxyuridine. The metabolite was isolated by solvent extraction and high-performance liquid chromatography and was identified by mass spectrometry as 5-(2-bromo-E-ethenyl)uracil.
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  • 57
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral properties of four classes of derivatives of thyronine are discussed (oxazolidinone, O-methyl oxazolidinone, O-acetyl oxazolidinone and N,O-diheptafluorobutyryl methyl ester). An assay for thyronine in human urine is described based on the N,O-diheptafluorobutyryl methyl ester. Results of To excretion in euthyroid humans were compared with those obtained previously using an assay based on the O-acetyl oxazolidinone derivative. Patients with frank hyperthyroidism had significantly higher To excretion than euthyroid subjects (2α 〈 0.002) and hypothyroid patients lower To excretions than enthyroid subjects (2α 〈 0.002). Some overlap between the two pathological ranges and the normal euthyroid range was evident.
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  • 58
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    Biological Mass Spectrometry 11 (1984), S. 273-275 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two commercially available compounds, silver methanesulfonate and silver trifluoromethanesulfonate, and a mixture of these compounds are useful as mass standards in field desorption mass spectrometry, offering certain advantages over compounds and methods currently being used for this purpose. These mass standards can be utilized in calibrating or confirming the accuracy of a data system or a mass marker calibration and for peak matching up to a mass of about 1440.
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  • 59
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    Biological Mass Spectrometry 11 (1984), S. 278-283 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A laser desorption time-of-flight mass spectrometer is used for structural confirmation of several acyl- and ether-linked glucuronides. Abundant molecular ion species are produced, as well as fragmentation reflecting both the molecular structure and the stability of the conjugates. The major ions are produced by cationization, and detection limits are as low as 1.6 ng (5.0 pmol).
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  • 60
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fragmentation behaviour of clavine alkaloids is discussed in relation to the influence of the ring D structure. The appearance of significant ions is correlated with structural features of clavines. Using linked scan techniques and deuterium labelling some mechanistic approaches were made.
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  • 61
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    Biological Mass Spectrometry 11 (1984), S. 296-300 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enzyme phenylalanine ammonia lyase taken orally has been found to reduce the rise in blood phenylalanine that normally occurs following a protein meal. Therefore the enzyme has a potential use in the management of the genetic disease phenylketonuria. The enzyme mediates the conversion of phenylalanine to cinnamic acid and its possible clinical future has necessitated a more detailed study of the product of its reaction. Cinnamic acid is a compound of low toxicity which is converted in the mammalian body primarily to hippuric acid. We have examined the kinetics of this process in a healthy male and in two patients with untreated phenylketonuria. In addition we have attempted to clarify the inconsistencies in earlier published work about the status of other, minor metabolites. Following an oral load of sodium (2H6) cinnamate there is an increase in urinary hippuric acid largely due to the excretion of (2H5) hippuric acid. In the subjects studied there was no major difference in the rate of elimination although the amount of cinnamic acid converted was less in those with phenylketonuria. This may reflect reduced first-pass absorption by the liver in untreated phenylketonuria enabling increased uptake to occur in other parts of the body.
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  • 62
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    Biological Mass Spectrometry 11 (1984), S. 284-289 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary gas chromatography column directly interfaced to a mass spectrometer was used for the analysis of sixteen benzodiazepines. The thermal stability of the drugs was found to be related to their chemical structure. Nine of the benzodiazepines were thermally unstable indicating that care should be taken in the interpretation of gas chromatographic data from this class of drugs. The unstable benzodiazepines were: ketazolam which decomposes to diazepam; N-4 oxides (chlordiazepoxide and demoxepam) which lose an oxygen radical; aromatic 7-nitro compounds (nitrazepam and clonazepam) which are partially reduced to the corresponding amine; α-hydroxy ketones (lorazepam and oxazepam) which decompose with the loss of water and N-methyl-α hydroxy ketones (Iormetazepam and temazepam) which partially decompose with the loss of a hydrogen molecule to produce the corresponding α,β-diketones. Few problems were encountered in distinguishing the drugs by their mass spectra, the exceptions being ketazolam which decomposes to diazepam and demoxepam which decomposes to desmethy Idiazepam. In general, good spectra were obtained from 20-50 ng of drug injected. However, for those compounds where the decompositions were not quantitative (nitrazepam, clonazepam, Iormetazepam, temazepam) detection limits were poor.
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  • 63
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    Biological Mass Spectrometry 11 (1984), S. 375-376 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potential of positive and negative Ion fast atom bombardment mass spectrometry in the examination of cyanogenic glycosides has been demonstrated by the analysis of linamarin, prunasin, neolinustatin and amygdalin.
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  • 64
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    Biological Mass Spectrometry 11 (1984) 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 65
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    Biological Mass Spectrometry 11 (1984), S. 383-385 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The secondary ion mass spectrometry, regardless of the charge status of the primary beam, is a good means not only of determining the type of phospholipid and the fatty acid components but also the isomeric positions of the acyl groups. Matrix-assisted secondary ion (SI) mass spectra of phosphatidylcholines in the positive mode show two characteristic doublets 2 u apart originating from the deacyl and deacyloxy cleavages of the compounds. The relative abundance of these ions is diagnostic of the ester positions, that is, the fragments originating from the C2-ester loss are more abundant than the corresponding ones from the C1-ester loss.
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  • 66
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    Biological Mass Spectrometry 11 (1984), S. 386-391 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Secondary ion mass spectra of tryptic peprides of human globin α-, β-, γ and α-chains were studied. Almost all mass peaks of protonated molecular ions of tryptic peptides were observed and they were very stable and abundant. The present results show the possibilities for quantitative analysis of two γ-globin species: Aγ and Gγ chains, and for structural analysis of unknown abnormal hemoglobins.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 67
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas chromatographic and mass spectrometric properties of the diethylsilyl (DEHS) or diethylsiliconide (DES)-DEHS ether derivatives of 20 hydroxysteroids of various types have been studied using N,O-bis(diethylsilyl)trifluoroacetamide as a new silylating agent. The mass spectra of the DES-DEHS ether derivatives were characterized by their marked simplicity and by molecular ions of high abundance, whereas the mass fragmentation patterns of the DEHS ether derivatives without formation of the DES group in the molecule were similar to those of the corresponding dimethylethylsilyl (DMES) ether derivatives. The appearance of the molecular ion may be very useful for estimating the molecular weight of hydroxysteroids of which other silyl ether derivatives yield molecular ions of insufficient abundance to characterize them. In particular, the DES-DEHS ether derivative of 5β-pregnane-3α,17α,20α-triol gave the molecular ion at m/z 506 as a principal ion in the electron impact ionization mode. The methylene unit values of the DEHS ether derivatives of hydroxysteroids without formation of DES groups were slightly larger than those of the corresponding DMES ether derivatives. A Δ[Um]s value was presented for estimation of the number of siliconide moieties in the DES-DEHS ether derivatives.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 68
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 400-402 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Fast atom bombardment mass spectrometry of the beta-gamma complexes of ATP and GTP with cobalt and chromium are reported. Spectra were recorded in the positive ion mode. Ions in the molecular weight region allow identification of the complexes to be made.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 69
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 408-414 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact mass spectra of some mono- and diamino derivatives of 5-phenyl-1,4-benzodiazepines have been determined, and their fragmentation pattern elucidated with the aid of deuterium-labelled derivatives, high resolution mass measurements and metastable analysis. The most significant ions are derived from the loss of the amino residues, and from the contraction of the seven-membered benzodiazepine system to give smaller rings.
    Additional Material: 5 Ill.