ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • General Chemistry  (9,300)
  • Analytical Chemistry and Spectroscopy  (4,318)
  • 1980-1984  (8,952)
  • 1925-1929  (4,666)
Collection
Publisher
Years
Year
  • 101
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 473-476 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution mass spectra were measured for six monohydroxy, 12 dihydroxy and eight trihydroxy isomers of methyl 5β-cholanates, which differ from one another in the position and configuration of hydroxyl groups at C-3, C-7 and/or C-12. Characteristic fragment ions serving to distinguish between the isomers are discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 102
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The negative ion chemical ionization mass spectra of the MO-TMS derivatives of the corticosteroids prednisolone, betamethasone and dexamethasone have been obtained using capillary column gas chromatography mass spectrometry. The spectra showed abundant diagnostic ions at m/z〉300 allowing for clear discrimination between the three steroid derivatives. A capillary column gas chromatographic mass spectrometric method using negative ion chemical ionization mass spectrometry has been developed to confirm the presence of the parent steroids in horse urine following the administration of proprietary preparations of prednisolone and betamethasone.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 103
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of debrisoquine and 4-hydroxydebrisoquine with hexafluoroacetylacetone to form pyrimidinyltetrahydroisoquinolines is used as the basis for a gas chromatographic mass spectrometric assay for these two compounds. The electron impact, positive ion chemical ionization and electron capture negative ion chemical ionization mass spectra of these pyrimidinyltetrahydroisoquinolines are described and compared. The latter were found to give an intense response under electron capture negative ion chemical ionization conditions, thus allowing the development of a much more sensitive assay for debrisoquine and 4-hydroxydebrisoquine. Derivatives of the hydroxyl group in 2-(4′,6′-bistrifluoromethyl-2′-pyrimidinyl)-4-hydroxytetrahydroisoquinoline were synthesized with a view to further improving the electron capture negative ion chemical ionization response. The resulting mass spectra showed extensive fragmentation for perfluoroacyl esters and halogenated silyl ethers. Only dimethylsilyl and trimethylsilyl ethers gave similar spectral responses to the parent compound.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 104
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex pattern of conjugates in the metabolism of antipyrine in man and rat has been investigated using an off-line combination of liquid chromatography and field desorption mass spectrometry. Using this approach, field desorption mass spectrometry enables the direct identification of underivatized glucuronides and sulphates in antipyrine metabolism on the basis of the corresponding protonated or cationized molecules representing the base peaks in the field desorption mass spectra. All conjugated metabolites of antipyrine established so far - four glucuronides and three sulphates - were identified in extracts of urine after stepwise purification by column chromatography and subsequent mass spectrometric analysis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 105
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 493-494 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe a method for simultaneous determination of terbutaline and salbutamol in plasma, based on gas chromatography chemical ionization mass spectrometry. Deuterium labelled terbutaline was used as internal standard for both drugs. The method has been used for the analysis of plasma samples obtained from asthmatic patients. The coefficient of variation at 0.3 ng ml-1 was 4.6% for terbutaline and 5.3% for salbutamol with a sample volume of 4 ml. The recovery of both drugs was 〉80%.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 106
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The negative ion chemical ionization mass spectrometry of bornyl butyrate, isobutyrate, valerate and isovalerate has been studied in detail. Collisional activation experiments have shown their analytical usefulness in the determination of the structure of the carboxylate fragment anions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 107
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The negative ion mass spectra of 52 organophosphorus pesticides obtained by chemical ionization with methane under electron capture conditions are presented. The influence of different ionization parameters on the total ion current as well as the relative intensities of the various fragment ions was investigated. In general, the mass spectra show few fragment ions, but these are characteristic for the chemical class of the compound (phosphate, phosphorothionate, phosphorothiolate, phosphorodithioate). The occurrence of the molecular anion is strongly dependent on the structure of the molecule and its ability to stabilize by charge delocalization the radical formed in the primary electron capture reaction. This takes place particularly in the organophosphorus esters of the parathion group which have an aromatic moiety with an electron attracting substituent. The phosphorothionates of the parathion group form a stable thiophenolate fragment which competes in the stability with the molecular anion. The relative intensity of these two ions in the spectrum is dependent on the ion source temperature.Because of the few, but intense fragment ions formed, negative ion mass spectrometry with multiple ion detection is expected to be a valuable tool for residue analysis in food and environmental samples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 108
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 499-504 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Combined liquid chromatography/mass spectrometry using a moving belt interface and commercially available glass lined stainless steel microbore reverse phase liquid chromatographic columns is described. The chromatographic performance is comparable with that obtained with conventional columns, and the lower mobile phase flow rates used enable improved liquid chromatographic/mass spectrometric sensitivities to be obtained since all the liquid chromatographic eluent can be handled by the interface and instrumental background due to solvent impurities is reduced. The utility of the approach is illustrated with studies of extracts from timbo powder, Imperatoria ostruthium and Calophyllum inophyllum. Using the carbamate pesticides IPC and CIPC the potential of microbore liquid chromatography/mass spectrometry for quantitative studies is demonstrated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 109
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. i 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 110
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. i 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 111
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. ii 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 112
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 113
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 505-509 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyloxime trimethylsilyl ether derivatives are frequently employed in gas chromatographic and mass spectrometric analysis of steroids. Under certain instrumental conditions, unusual mass spectra were recorded from some corticosteroid methyloxime trimethylsilyl ether derivatives, reflecting degradation by contact of the steroids with active surfaces in the gas chromatograph mass spectrometer interface. This occurred prior to electron impact ionization. Fragmentations of the degradation products of methyloxime trimethylsilyl ether derivatives of tetrahydrocortisol and tetrahydrodeoxycorticosterone are described, as representatives of C21 steroids with dihydroxyacetone and α-ketol side chains. Elemental compositions of ions were confirmed by high resolution mass spectrometric analysis. Derivatives of steroids with glycerol side chains, e.g. cortolone, showed no evidence of degradation. The problem was overcome by ensuring inertness of the glass restrictor interface and by preventing, as far as posssible, contact of sample with metal surfaces in the source housing.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 114
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 522-526 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of N- and S-oxides of fluphenazine, and its decanoate ester, have been examined by the relatively new techniques of desorption chemical ionization and fast atom bombardment mass spectrometry. Both techniques yielded molecular ion or pseudo molecular ion information, which is not readily obtainable by conventional mass spectrometry. In particular, the advantages of fast atom bombardment are demonstrated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 115
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 510-514 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homoharringtonine and harringtonine are esters of cephalotaxine and are naturally occurring alkaloids in certain coniferous trees in China. These compounds have been shown to have activity against certain types of leukemia in cell cultures, experimental animals, and initial clinical trials in China, and will undergo Phase I trials in several institutions. A gas chromatographic mass spectrometric technique was developed for the quantification of both drugs in serum. One drug serves as internal standard for the other. The drugs are extracted from serum with dichloromethane and are quantified by monitoring the protonated molecular ions of the trimethylsilyl derivatives obtained by chemical ionization (methane). Masses monitored are: m/z = 690 for homoharringtonine and m/z = 676 for harringtonine. Detection limit: 10 ng ml-1 (20 nmol); reproducibility: 1.6-15.0% in the 0-200 ng ml-1 range. Serum levels of harringtonine reached 145 ng mg-1 upon intraperitoneal injection of 3mg kg-1 in BDF-3 mice.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 116
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 70 eV electron impact mass spectra of various deuterated biotin methyl esters are reported and discussed. Using the fragment ion [D]+ at m/z 185, it is possible to determine the total deuterium content in positions other than Cg. Unimoiecular decompositions in the 2nd field free region (mass analysed ion kinetic energy spectra) of the molecular ion give rise to the specific formation of ion [D]+ and of the two isomeric ions [C]+ and [C′]+ at m/z 198. Furthermore, only ion [C]+ (and not [C′]+) loses a molecule of methanol to lead to the two isomeric ions [E]+ and [E′]+′ at m/z 166. These specific fragmentations allow the localization of deuterium on positions 3,4 and 5 of the thiophane ring of biotin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 117
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several steroids generated by microbial fermentation of cholesterol were identified by the mass analysed ion kinetic energy (MIKE) spectra of their molecular ions generated under electron impact, and quantified by selected metastable ion monitoring. These analyses were performed on a crude solvent extract without any purification or molecular separation procedures. The detection limit was below the nanogram range. Identification and quantification of the major constituents, namely androst-4-ene-3,17-dione and androsta-1,4-diene-3,17-dione were fast and easy. Pregnenolone and progesterone which were present at a much lower level were identified with more difficulty by their MIKE spectra alone, because of the existence of isobaric interfering ions. Nevertheless, their quantification by single or dual metastable monitoring was possible.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 118
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An O-demethylated and two mono-hydroxylated metabolites of levomepromazine have previously been identified as conjugates in the urine from psychiatric patients. The three metabolites were identified in hydrolysed and nonhydrolysed plasma and erythrocytes from three patients by selected ion monitoring of the trimethylsilyl derivatives, with a mass spectrometric resolution of 5000. The three metabolites were mainly found as conjugates in the plasma, and smaller amounts were found unconjugated in the plasma and the erythrocytes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 119
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 539-545 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly sensitive and specific method for the quantitative determination of nicotine in plasma is described. Using simple one-step work-up tchnique and (5′,5′-2H2) nicotine as internal standard, the analytical procedure is based on combined capillary column gas chromatography and high resolution selected ion monitoring. Incorporation of a specially designed gas chromatograph/mass spectrometer interface allowing introduction of the eluent by a fused silica capillary via the direct inlet port into the ion source brings the detection level for nicotine in an alcoholic solution down to below 100 fg. The discriminatory nature of the method also makes it well suited for studying ambiguities of instrumental nicotine assay and some of these are discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 120
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly sensitive and selective glass capillary gas chromatographic negative ion chemical ionization mass spectrometric assay was developed to measure peptidoaminobenzophenone(2-o-chlorobenzoyl-4-chloro-N-methyl-N′-glycylglycinanide) and its metabolites; chlorodiazepam, chlorodesmethyldiazepam and lorazepam in human plasma. As peptidoaminobenzophenone underwent pyrolysis during gas chromatography, it was converted to a thermally stable aminoquinolone. Internal standards for these compounds were the respective deuterium labelled compounds. Calibration curves were prepared for the range of 1-100 ng ml-1. Interference by endogenous substances was negligible in the isobutane negative ion chemical ionization mode in contrast to the electron impact or positive ion chemical ionization mode. This method was used to determine the plasma levels in humans following oral administration of two 5 mg doses.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 121
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 122
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 557-558 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 123
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 552-556 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cisplatin, cis-Pt(NH3)2Cl2, is used as an anticancer drug. In the present work, we show that fast atom bombardment mass spectrometry is a useful technique in the structural investigation of a complex containing one molecule of cisplatin and two guanosine molecules. Elemental composition and structures of characteristic ions have been postulated and confirmed by direct isotopic analysis, by the study of their collisional induced dissociation and their metastable spectra. Thus, fast atom bombardment mass spectrometry seems to be a useful tool for the characterization of platinum-nucleosides adducts.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 124
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A technique for the detection of biotransformation products of xenobiotics in crude urine extracts by field desorption mass spectrometric profile analysis is described. The method comprises determination of peak profiles of a series of blank and test samples using low resolution field desorption mass spectrometry, comparison of averaged peak profiles and noise reduction by means of Fisher and ratio weighting of peak intensities. Application of the technique to 3,5-dinitro-2-hydroxytoluene has resulted in the detection of two hitherto unkown metabolites in rat urine. By thin-layer co-chromatography, high resolution electron impact mass spectrometry and thin-layer chromatographic/field desorption mass spectrometric analysis they could be identified as 3,5-dinitro-2-hydroxybenzenemethanol and 3,5-diacetamido-2-hydroxytoluene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 125
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment ionization of peptides yields intense [M + H]+ and [M - H]- ions. The collisional activation spectrum of the [M + H]+ ion of a heptapeptide yields more sequence information than the mass spectrum and is not polluted with interfering peaks originating from impurities.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 126
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 17-23 
    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 spectra of by-products in the synthesis of Iopamidol are reported and their mass spectrometric fragmentation processes are discussed. This technique represents the ionization method which gives the best structural information on Iopamidol and similar compounds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 127
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 5-12 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical ionization mass spectra of several permethylated oligosaccharides were studied using isobutane and ammonia as reagent gases. In the molecular ion region, protonated molecule [MH]+ or ammonium adduct ion [M·NH4]+ were observed. Fragmentations were mainly restricted to the cleavages of the glycosidic bonds between the glycosidic oxygen and the anomeric carbon atoms. Resulting fragment ions were classified into oxonium type ions and their counterpart ions with hydrogen or methyl transfer, which were very useful for determining the sequence of the constituent saccharide units. These ions were confirmed by shift techniques with pertrideuteromethyl derivatives, deuterated reagent gases, i-C42H10 and N2H3, and 15NH3. Finally, these results were applied successfully to the structural characterization of the unknown trisaccharides, viridotriose A (6), B (7) and C (8).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 128
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 24-29 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of liquid chromatography mass spectrometry to two groups of thermally labile pesticides, carbamates and ureas, is reported using a moving belt interface system with methane as reagent gas. Thermal decomposition of six selected representative members of these two chemical classes has been successfully avoided by this technique and in many cases, molecular weight evidence was available for detection and characterization. Moreover, the system was explored as to its quantitative capabilities and the preliminary results have indicated that such an analytical approach is satisfactory for regulatory analysis of crop residues at the ppm level.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 129
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 30-33 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple preparation for the synthesis of (2H9)trimethylanilinium hydroxide is detailed. The utility of this deuterated ‘on column’ permethylation reagent for the preparation of volatile derivatives of nucleosides for gas chromatographic mass spectrometric analysis is described.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 130
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 46-49 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The incorporation of a conversion dynode, positioned in the available space between the ion exit hole of the quadrupole and the entrance of the electron multiplier permits the detection of negative ions when this dynode is held at a high positive potential (4 kV). The system makes use of the original electron multiplier and does not require additional electrical feedthroughs into the vacuum system. The conversion dynode is also used for positive ion detection. It is then kept at -4 kV and helps to increase the gain for high mass ions, to reduce mass discrimination and to improve the signal to noise ratio.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 131
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 34-45 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral fragmentations of 3-deazauracil, 3-deazauridine and selected derivatives are described. Fragmnetations give rise to ions diagnostic of specific positions in the base and/or sugar moieties. Ion structure are rationalized based on isotopic labeling, metastable ion analysis and high resolution data. The spectrum of 3-deazauracil resembles that of cytosine more closely than uracil. The spectrum of 3-deazauridine is almost identical to that of 1-β-D-arabinofuranosyl cytosine, closely resembles that of cytidine and differs significantly from uridine. The formation of a strong b+41 ion in the spectrum of 3-deazauridine raises questions on the utility of the b+41 ions in assigning a cytidine structure to an unknown nucleoside based solely on this ion.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 132
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 133
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 50-56 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment mass spectra of a 6-O-methylglucose polysaccharide of molecular weight 2852 dalton are described. Fragmentation pathways in both positive and negative modes are defined. The presence of cationized sequence ions in the positive spectra is confirmed by salt dosing experiments. Positive spectra obtained using monothioglycerol as the supporting matrix are compared with data obtained using glycerol. The potential importance of three dimensional structure in controlling the fragmentation behaviour of large molecules under FAB conditions is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 134
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 57-60 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The computer program PAAS has been in use for about two years and recently several useful features have been added, which help to predict and interpret mass spectra of peptides and their residues particularly for determining amino acid sequences.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 135
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 65-73 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After oral application of 14C labelled fendiline, 13 metabolites of this drug could be identified in human urine. Only traces of parent fendiline were excreted in the urine. The main pathway of metabolism is hydroxylation of phenyl groups with subsequent glucuronidation and sulphation. On the other hand, oxidative dealkylation occurs with the amino group remaining at the 3,3-diphenylpropyl moiety and p-hydroxyacetophenone being formed almost entirely from the 1-phenylethyl group.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 136
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 61-64 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An alternative source for the generation of fast atom beams developed for fast atom bombardment mass spectrometry is described. The principle of operation is based on a Capillaritron ion source described elsewhere. Easy to operate with any gas and requiring low maintenance, the source should prove extremely useful for the analysis of high molecular weight compounds. Residual ions are separated from fast atoms, produced by a novel charge transfer geometry, before the beam emerges from the source. Power calorimetry was utilized as the diagnostic technique to quantify and evaluate the fast atom beam parameters. Using 8 kV Xenon beams, measurements of ion currents and power density fluxes were made with and without ion beam deflection. It was determined that the power contribution due to fast atoms in an undeflected beam can vary from 40% to 80% of the total power delivered to a target depending on the gas flow rate and ion beam energy. In one case, it is shown that 42% of the total power imparted to a probe consisted of fast Xenon atoms corresponding to a deposition at the target of 16 mW cm-2. Below a certain gas flow rate, depending on the gas, the power density was determined to be flow rate dependent. Above this value, the peak power density is constant and limited to further increases by space charge effects in the ion beam. A sample spectrum using a fast atom Capillaritron source installed on a Hewlett-Packard 5985B quadrupole mass spectrometer is shown.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 137
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 74-77 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dimethylphosphate esters of vitamins D2 and D3 and of 7-dehydrocholesterol give satisfactory mass spectra under electron impact using the direct introduction probe, while this method is not suitable for the related phosphorodichloridates, which undergo to thermal decomposition-polymerization processes. Such processes are avoided using the direct electron impact method. Abundant molecular ions or their protonated analogues are obtained by field desorption.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 138
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 78-82 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligopeptides subjected to partial enzyme hydrolysis provide mixtures of sub-peptides which optimize amino acid sequence determination by fast atom bombardment mass spectrometry. The digestion mixture can be sampled directly; there is no interference from the enzyme. Complete sequences were obtained from spectra recorded on 1-5 nmol samples after digestion at 37°C for times ranging from 0.1-4.0 h. The qualitative results of attack by two exopeptidases on three oligopeptides are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 139
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron capturing pentafluorobenzyl ester derivatives of prostanoids provide intense negative ion chemical ionization mass spectra. Fragmentation is directed almost entirely away from the prostanoid molecule and this provides intense [M - C6F5CH2]- ions. These ions are ideal for specific and sensitive quantitative selected ion monitoring analysis. The limits of sensitivity employing this technique are in the range 1-8 pg on column compared with 100-500 pg using the corresponding methyl ester derivative in the electron impact mode. The capillary column characteristics of the pentafluorobenzyl esters are suitable for the development of multiprostaglandin gas chromatographic mass spectrometric assays.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 140
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A group of 20 inbred mice were inoculated intraperitoneally with sarcoma I cells. Urine specimens were collected before and after inoculation from this group as well as from a group of 20 mice for controls. Mass profiles of these groups were obtained by volcano field ion mass spectrometry and compared. Significant differences in average normalized mass peaks between the two groups after inoculations are observed for most of the peaks analysed from mass 84 to 313. There is sufficient diagnostic power in the mass profiles to permit unambiguous separation of the diseased mice from the healthy ones.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 141
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 94-97 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A saddle field fast atom bombardment gun was installed on a quadrupole mass spectrometer and its performance evaluated. Only some minor modifications to a standard gas chromatography mass spectrometry system were required to accommodate this source. Using xenon as the bombarding atom, measurements were made with respect to sensitivity, background effects, sample type, calibration of the data system and other parameters pertinent to the operation of a fast atom bombardment source on a quadrupole system. The simplicity of operation and its unique ability to produce gaseous ionic species from highly polar molecules in solution make it an ideal complement to other mass spectrometric ionizing devices.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 142
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 98-102 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experiments involving the monitoring of enzyme catalyzed reactions occurring within a fast atom bombardment mass spectrometer are reported. Data are presented using FAB mass spectrometry to monitor trypsin and dipeptidyl aminopeptidase I catalyzed hydrolysis of their respective assay substrates and for hydrolysis of the peptide (val4) angiotensin III by yeast carboxypeptidase Y. Enzyme catalysis was followed by measuring the decrease of abundance of the [M + H]+ ion of the substrate and the increase of that of the product from a mixture of enzyme and substrate in a glycerol/water matrix placed on the probe inside the mass spectrometer. In addition, results of preliminary experiments to determine the survival of live yeast cells on exposure to FAB mass spectrometry is also presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 143
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 144
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 107-112 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Discrete aqueous solution volumes were nebulized and introduced into an inductively coupled plasma (ICP) operated at atmospheric pressure. Metallic elements in the injected sample were atomized and ionized to yield a pulse of sample ions lasting approximately 20 s. A fraction of these sample ions was extracted into a vacuum system where the ions were m/z resolved and detected. Pulse counting and signal averaging techniques were used to determine isotope ratios for Mg and Ni present at 2-40 mg I-1 in solution volumes of 50-200 μl. The precision of these isotope ratio determinations was ± 1-3%. This ionization method is potentially valuable for determining metal isotope ratios in solution samples at high sample throughput rates, e.g. one sample every 3-4 min.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 145
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 113-113 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 146
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Decafluorotriphenylphosphine has been shown to be a useful compound for checking the overall performance of gas chromatography mass spectrometry systems in the electron impact (EI) mode of operation. This paper reports the results obtained on several compounds evaluated for their utility in checking mass spectrometric performance in the chemical ionization mode of operation. The ideal compound should be capable of being admitted to the ion source from both the solid probe inlet and the gas chromatographic inlet, should respond in both positive ion and negative ion modes, should have as high a molecular weight as possible (preferably 〉 400), should generate an abundant ion indicative of the molecular weight and several significant fragment ions covering a wide mass range in positive ion chemical ionization (CH4), and should generate less fragmentation in positive ion chemical ionization with less exothermic reagent gases. Following an evaluation which included such compounds as benzophenone, decafluorotriphenylphosphine, octacosane (n-C28H58), triacontane (n-C30H62), and methyl stearate, lauryl laurate (mol. wt = 368) was found to offer the best compromise in satisfying these criteria.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 147
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, high-performance liquid chromatographic and mass spectrometric analysis of N4-trideuteroacetylsulphamerazine is described. N4-trideuteroacetylsulphamerazine in man is deacetylated into sulphamerazine, which in turn is acetylated again into N4-acetylsulphamerazine. The existence of a deacetylationacetylation equilibrium in man has been demonstrated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 148
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 126-129 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The [M-1]- ion sometimes observed in the methane electron capture/negative chemical ionization mass spectra of diazepam and nordiazepam is [M-H]-. Generation of the [M-H]- ion is caused by trace amounts of oxygen in the ion source. For nordiazepam the Hż lost from the [M]-ż ion is that on the amide nitrogen. For diazepam the Hż lost from the [M]-ż ion is that on the carbon adjacent to the amide carbonyl. The [M-1]- ion generated by negative chemical ionization is structurally different from the [M-1]+ ion generated by positive electron ionization. At ion source temperatures greater than 150°C, the methane electron capture/negative chemical ionization mass spectra of diazepam and nordiazepam consist principally of [Cl]- ions. A comparison of the relative sensitivities of various analogs of diazepam and nordiazepam suggests that electron capture occurs at the imine bond.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 149
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 120-125 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatography mass spectrometry has been used for over a decade for the determination of the amino acid sequences of fragment peptides derived from larger parent molecules. The majority of these fragments have from four to seven residues and several different methods of derivatization have been devised. Few reports have been published in which similar techniques have been used for the quantification of such peptides, but there is a growing list of small peptides which have been shown to have biological activity in their own right. This report is concerned with the development of a gas chromatographic mass spectrometric assay for the two eosinophil chemotactic peptides, Val-Gly-Ser-Glu and Ala-Gly-Ser-Glu, which appear to have a role to play in the course of the inflammatory process in skin disorders.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 150
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 136-142 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatography mass spectrometry with selected ion monitoring has been used to develop a method for the quantification of ketotifen and its demethylated, 10-hydroxy and 10-hydroxy demethylated metabolites in human plasma. The minimum detectable concentrations for ketotifen and its demethylated metabolites were 50 pg ml-1 and 300 pg ml-1 for the 10-hydroxy metabolite. The methodology has been applied in studies of the kinetics of the drug in man, and plasma levels of the unchanged drugs and its metabolites in free and conjugated form are reported.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 151
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 130-135 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To evaluate the accuracy of glucose methods, we have set up an isotope dilution gas chromatographic mass spectrometric method where methyloxime trimethylsilyl derivatives of monosaccharides were separated with a SP-2100 fused silica column. An autodiluter was found suitable for delivering aliquots for derivatization: CV of 0.13% (aqueous) and 0.24% (serum). Ions at m/z 319 (non-labelled) and 323 (deuterium-labelled) were selected for glucose, galactose and mannose, and at m/z 307 and 311 for fructose. Optimization of ion monitoring with a Finnigan 4000 gas chromatograph mass spectrometer 6110 data system was limited to one scan per second without full compensation for 0.1 u shifts. A CV of 0.65% in isotope ratios was obtained for 30 injections (three per vial) of one glucose standard. A similar variation between duplicate injections was obtained with serum. Glucose measurements on 36 serum specimens (six individuals) were made by gas chromatography mass spectrometry and by both a manual (reference) and a flow-through method using hexokinase and glucose-6-phosphate dehydrogenase. Mean glucose by gas chromatography mass spectrometry was 5.57 mmol l-1; bias was -1.7% manually and +1.2% by the automated method. Average concentrations (mmol l-1) of other hexoses were low: mannose (0.058), fructose (0.015) and galactose (0.005). Glucose measurements of two control sera bracketed with standards showed satisfactory agreeement between the three methods. CV of 1.2 to 1.4% by gas chromatography mass spectrometry indicate that further refinements are required.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 152
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 143-154 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The modification of alcoholic and phenolic compounds as their tert-butyldimethylsilyl ether derivatives has found wide use in the separation of complex mixtures by gas chromatography and in their quantification by gas chromatography mass spectrometry with selected ion monitoring. In comparison, the formation and use of the tert-butyldimethylsilyl ester derivatives has received little attention. This paper examines some of the factors involved in the esterification of fatty acids using a number of tert-butyldimethylsilyl reagents, delineating optimum conditions for derivative formation. In addition, using hydroxy fatty acids, differences in the selectivity of silylation between these tert-butyldimethylsilyl reagents and their trimethylsilyl analogues are demonstrated, which are manifested in the discrimination between silyl ester and silyl ether formation. The application and limitation of these techniques is discussed with reference to the quantification, by gas chromatography mass spectrometry selected ion monitoring of unsaturated fatty acids and hydroxy fatty acids as their tert-butyldimethylsilyl derivatives. The measurement of arachidonic acid obtained from human skin, where sample size is often limited, is illustrated using a stable isotope dilution assay. These results are compared to those obtained using the methyl ester.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 153
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 155-161 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computer system (MSSMET), using methylene unit retention indices for an off-line reverse library search analysis of selected ion chromatograms from gas-liquid chromatographic mass spectrometric data, has been applied for the qualitative and quantitative determination of daily variations in the excreted levels of urinary steroids of two individuals, using capillary column gas-liquid chromatography. Aliquots of 24 h urine collections and morning spot urine samples were examined. The daily excretion pattern of most of the major steroid metabolites was fairly consistent from day to day (i.e. 3α-hydroxy-5α-androstane-17-one, androsterone; 3α-hydroxy-5β-androstane-17-one, etiocheolanolone; 3α, 17α,21-trihydroxy-5β-pregnane-11,20-dione, THE; 3α,11β,17α,21-tetrahydroxy-5β-pregnane-20-one, THF; 3α,11β,17α,21-tetrahydroxy-5α-pregnane-20-one; allo-THF; 3α,17α,20α,21-tetrahydroxy-5β-pregnane-11-one, cortolone; 3α,17α,20β,21-tetrahydroxy-5β-pregnane-11-one, β-cortolone; 5β-pregnane-3α,11β,17α,20α,21-pentol, cortol; 5β-pregnane-3α,11β,17α,20β,21-pentol,β-cortol), while certain other steroid metabolites had a less consistent excretion pattern (3β-hydroxy-5-androstene-17-one, for example). Advantages and disadvantages of using capillary columns for the automated metabolic profile analysis of urinary steroids by reverse library search of selected mass chromatograms.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 154
    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 quantitative determination of pinaverium-bromide, a quaternary ammonium derivative with papaverine-like activity, in human serum. The method involves a chloroform extraction of serum spiked with N-(6,6-dimethyl bicyclo[3.1.1]2-heptenyl-ethoxyethyl)perhydro-1,4-oxazine as internal standard. After evaporation of the solvent, and reduction of the residue with Raney-Nickel, the internal standard and the reduced pinaverium-bromide are re-extracted from the reaction mixture with toluene and analysed isothermally on a fused silica column coated with OV-101. Although chemical ionization with methane revealed intense protonated molecular ions for both pinaverium-bromide and the internal standard, selectivity and sensitivity were significantly lower in comparison with electron impact ionization at 70 eV. Therefore, quantification was performed in the electron impact mode by single ion monitoring of the common fragment ion at m/z 100.2. A linear detector response was observed up to 160 ng ml-1. A within-run assay precision better than 2% CV (n=5) was found, and a detection limit of 1 ng pinaverium-bromide ml-1 of serum was attained.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 155
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The technique of isotope dilution mass spectrometry was used for the measurement of equiline and oestrone as well as the sulphate esters of the two phenolic steroids in serum. Serum samples were obtained from an ovariectomized woman who received a tablet of 1.25 mg of various conjugated equine oestrogens. For the measurement of the non-conjugated oestrogens 20 pg (2,4,16,16-2H4)equiline and 100 pg (6,7-3H2)oestrone were added to serum samples of 0.5-4.0 ml. The steroids were extracted with 15 ml ether and separated from each other by column chromatography on Sephadex LH-20. This was followed by derivative formation with heptafluorobutyric anhydride. The ester derivatives of the two steroids were injected into a SE-52 capillary column which was coupled to a mass spectrometer. For the recording of equiline and the corresponding isotopically labelled equiline the instrument was adjusted to m/z 464 and 468, respectively. For the measurement of oestrone and (6,7-3H2)oestrone the m/z values 466 and 470 were monitored continuously. The amounts of equiline and oestrone in the serum samples were calculated from the isotope ratios measured by selected ion monitoring. For the determination of the sulphate esters of the oestrogenic steroids the serum samples (0.5-4.0 ml) from which the non-conjugated steroids had been removed by ether extraction were treated with 15 ml methanol. The serum proteins were sedimented by centrifugation and the methanolic supernatant was evaporated to dryness. The sulphate esters of the phenolic steroids were then hydrolysed by enzymatic cleavage. After an incubation period of 48 h, 50 pg (2,4,16,16-2H4)equiline and 150 pg (6,7-3H2)oestrone were added to the mixture. The oestrogens were then extracted with cyclohexane and determined as described for the measurement of the nonconjugated phenolic steroids. The precision of the method for the measurement of equiline in the range from 1.5-50 pg was at 7.3% (CV) and for oestrone in the range from 30-150 pg at 3.6% (CV). The accuracy of the procedure was achieved by the use of the isotope dilution principle in combination with the highly specific technique of selected ion monitoring.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 156
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantitative gas chromatography/mass spectrometry/selected ion monitoring of mandelic acid in plasma in the lower micromolar range has been investigated using both the deuterated compound and a homologue, 2-phenyllactic acid, as internal standards. On chromatography of the TMSi-ester ethers, the latter is less stable than the former. The chromatographic isotope effect observed for deuterated mandelic acid does not suggest a carrier function for this compound. Normal plasma levels of mandelic acid are about 0.5 μM. Only a minor portion of phenyramidol is metabolized to mandelic acid. Preliminary in vivo data indicate that presence of a stereoselective transport system for D(-)-mandelic acid in gastrointestinal tract and possibly kidney.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 157
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Numerous monofunctional amines have been reacted with dimethylthiophosphinic chloride to form stable derivatives. Their good gas chromatographic properties and abundant molecular ions afforded highly sensitive and specific detection by selected ion monitoring (SIM) down to the picogram level. Based upon this derivatization procedure, new methods for the determination of aniline in serum and urine by SIM were developed. The minimum detectable concentration of aniline was 500 pg ml-1. Linear response curves were obtained from 1.5 to 150 ng ml-1 using (2H5)aniline as the internal standard. Specific derivatization of a series of bifunctional amines was achieved with methyldichlorophosphine and sulfur resulting in the formation of stable phospholidine-thiones. These derivatives chromatograph well on nonpolar stationary phases, and their mass spectra exhibit abundant molecular ions. This derivatization reaction was applied to the quantification of ephedrine from urine and serum by SIM with (2H2)ephedrine as the internal standard. The detection limit of the method was 1 ng ml-1. The linearity was established in the range from 10 to 160 ng ml-1.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 158
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A non invasive method for measurement of bile acid kinetics in serum using (24-13C)chenodeoxycholic acid has been developed. After oral administration of 50 mg (24-13C)chenodeoxycholic acid, the exponential decay of the 13C atom percent excess was measured in serum using capillary gas chromatography mass spectrometry. This required that isotope ratios were measured with high accuracy and coefficients of variation less than 1% by means of selected ion monitoring and scan averaging. The clinical applicability was tested by repeated determination of pool size, fractional turnover and synthesis rate of chenodeoxycholic acid in one healthy volunteer. This method permitted the determination of pool size, synthesis and conversion of chenodeoxycholic acid into lithocholic acid in man without the use of radioactive tracers and without repeated duodenal intubation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 159
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectrometry and stable isotope dilution have been used for direct trace analysis of metals in urine. Samples were collected over 24 h at 2 h intervals from a hospitalized multiple sclerosis patient. Quantitative determinations of Li+, Rb+, Mg2+ and Sr2+ from individual samples have been made and correlated with the amounts of urine excreted as well as with the time of day. The concentrations of Na+ and K+ were determined by flame photometry. The quantities of metals excreted in urine during the course of 24 h were 0.0129 mg for lithium, 4700 mg for sodium, 2100 mg for potassium, 1.4 mg for rubidium, 78.8 mg for magnesium and 0.2356 mg for strontium. The maximal absolute quantities excreted of all metals determined correspond with the largest volume of urine. The highest amounts of potassium, rubidium and strontium were found in urine during the daytime (8.00-20.00), whilst magnesium was excreted increasingly during the night hours (20.00-8.00). The excretion of lithium and sodium is fairly even over the entire 24 h period. It is noteworthy that similarities in the excretion profile and the concentration course are observed between Li+ and Na+ on one hand and between K+ and Rb+ on the other. Moreover, the lower concentration of Rb+ ions in urine of multiple sclerosis patients, in comparison to healthy individuals and clinical controls as reported previously, was confirmed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 160
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 197-202 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a substantial part in the development of a reference material in clinical chemistry, a highly accurate and precise isotope dilution mass spectrometric method has been worked out for the determination of cortisol in human serum. The candidate definitive method consists of addition of 4-[14C]cortisol and, following equilibration, solvent extraction of cortisol and its internal standard from the serum matrix. After conversion into methoxime-trimethylsilyl derivatives, the extract is purified by gel chromatography. Measurements are made by combined capillary gas chromatography mass spectrometry. The ratio of peak heights at m/z 605 and 607 for each sample and calibration mixtures is used for quantification. To ensure maximum accuracy each set of calibration mixtures was composed from two stock solutions and closely bracketed the anticipated serum concentration. An analysis of variance, involving comparison of within-run and between-run variability, gave a total coefficient of variation (CV) of 0.38% for a serum pool containing 90.79 ng cortisol ml-1 serum.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 161
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 203-208 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical ionization mass spectra of dexamethasone and betamethasone have been obtained via liquid chromatography mass spectrometry using a moving belt interface. These results have confirmed a concentration-dependent competition between thermal degradation and vaporization. Caution should be exercized when dealing with molecules subject to thermal instability since sample introduction via the mechanical transport system does not guarantee evaporation without thermal decomposition.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 162
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A confirmation method which can be used in regulatory screening programs for diethylstilbestrol in the urine of cattle is presented. trans- Diethylstilbestrol is purified from urine by Sep-Pak extraction and high-performance liquid chromatography and converted into its trimethylsilyl derivative. Identification is based on both accurate mass measurement of the molecular ion of trans-diethylstilbestrol trimethylsilyl by gas chromatography high resolution mass spectrometry and determination of the [M + 1]+/[M]+ peak height ratio by selected ion monitoring in low resolution. Specificity is such that on the basis of mass spectrometric data alone, all molecular formulae except those of diethylstilbestrol trimethylsilyl and only one other compound can be excluded. Additional specificity is provided by chromatographic data. The quantification is based on the standard addition method. The average recovery of trans-diethylstilbestrol is 76% with a standard deviation of 18% (n = 23).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 163
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 164
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 220-226 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main classes of human plasma lipids, free fatty acids, cholesterol, cholesterol esters, triglycerides and phosphatidylcholines were identified and quantified from samples of human plasma by field desorption mass spectrometry. A crude lipid extract was prepared from 50 μl of human plasma and a 1-5% aliquot thereof was subjected directly to field desorption mass spectrometry without any chromatographic separation of the extract constituents. Within the classes of free fatty acids, triglycerides and phosphatidylcholines the fatty acid profile was obtained directly from the mass spectrum and accurate quantification could be achieved by the addition of stable isotope labelled internal standards.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 165
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 215-219 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Negative ion mass spectra obtained by fast atom bombardment of glycerol solutions of steroid sulphates include the steroid sulphate anion as the single prominent feature. High sensitivity is achieved, with full spectra obtained for samples of less than 15 ng. Differentiation of the isomeric steroids, dehydroepiandrosterone sulphate and testosterone sulphate, is made by comparison of the products of fragmentation of metastable ions. Analyses of biological extracts suffer from poorly-understood matrix effects which may cause partial or complete suppression of the signal attributable to steroid sulphates. Use of an immunoadsorption extraction technique, however, has permitted the detection and approximate quantification (using a (2H2) analogue as internal standard) of dehydroepiandrosterone sulphate in blood plasma. Interference from glycerol background is avoided by preparation of the pentafluorobenzyloxime derivatives.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 166
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methods are described to extract and measure 2,3-bis(3-hydroxybenzyl)-γ-butyrolactone (enterolactone) and 2,3-bis(3-hydroxybenzyl)butane-1,4-diol (enterodiol) from physiological fluids. They are based on the use of stable labelled analogues of each compound as internal standards with end point assay being by gas chromatography mass spectrometry. The methods were developed to quantify enterolactone and enterodiol in experiments designed to investigate the significance and source of these compounds in man and animals. Examples of studies on human ovarian blood and investigations of their excretion in urine following dietary manipulation are described.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 167
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 237-252 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A compilation of reference to the development and application of the dynamic combination of liquid chromatography and mass spectrometry is presented. Additionally, author and subject indices have been complied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 168
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 253-257 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The urine of two patients with propionic acidaemia contained 3-ethyl-3-hydroxyglutaric acid which has a propionyl residue in place of one of the acetyl residues of the normal metabolite 3-methyl-3-hydroxyglutaric acid. Related compounds, 2,3-dimethyl-3-hydroxygIutaric acid, 2-methyl-3-ethyl-3-hydroxyglutaric acid and 2,3,4-trimethyl-3-hydroxyglutaric acid, could not be detected in propionic acidaemia urine, but 2,3-dimethyl-3-hydroxyglutaric acid was excreted by a patient with β-ketothiolase deficiency.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 169
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 258-261 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Another promising application area for tandem mass spectrometry is targeted class analysis. Particularly favorable examples of this are analyses for penicillins and other β-lactams, important compound classes sought in complex mixtures. Electron ionization of these compounds produces a major fragment ion by lactam ring cleavage; collisionally activated dissociation of this ion yields spectra characteristic of the compound class. Four isomeric [C7H12NO2S]+ ions and two homologous ions illustrate these points. Their collisionally activated dissociation spectra, like the corresponding molecular electron ionization spectra, show fragmentations characteristic of the β-lactam ring size and of substituent type and position, but not of stereochemistry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 170
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We examine the difference between a linear and a non-linear model for the calculation of analyte concentration by interpolation between standards in isotope dilution/mass spectrometry. Equations are developed for calculating this difference for various increments of the bracketing intensity ratios and for various compositions of the sample; graphs are also presented to depict this difference for these various conditions. As an illustration, the result for a series of measurements on urea are presented and discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 171
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 269-275 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Negative ion mass spectra of several free nucleosides as well as their trifluoroacetyl, trimethylsilyl, and 2′-o-nitrobenzyl derivatives are reported. A low ion source pressure is used so that the processes of collisional stabilization and ion/molecule reactions often associated with negative ion chemical ionization do not occur. The utility of such spectra for identification of these and similar nucleosides which may be present as unknowns is discussed. Details of modifications for acquiring negative ion mass spectra using an LKB-9000S mass spectrometer are given.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 172
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reliability of radioimmunoassays for determination of PGE2 and PGF2α in gastrointestinal fluids was checked by two gas chromatographic mass spectrometric methods. Analyses were performed on samples of gastric juice from dogs and man (healthy volunteers), jejunal fluids from patients with celiac disease, mucous discharge from a villous adenoma of rectum, and bathing solutions from the Ussing chamber containing human jejunal mucosa. The radioimmunoassays included extraction and Sephadex LH-20 chromatography as a preliminary purification before quantification was carried out. Gas chromatographic mass spectrometric analysis of PGE2 was performed by monitoring the molecular ion of the trimethylsilyl ether of PGB2 methyl ester, m/z 420 and m/z 424 for the protium and the deuterium form, respectively, while PGF2α was quantified as the triacetyl derivative of the methyl ester, using the ion pair (M-3 × 60) i.e. m/z 314 and m/z 318. Recovery of immunoreactive PGE2 relative to gas chromatographic mass spectrometric dosage was 88.5% ± 6.5 (mean ± SEM; n = 13), while the amount of PGF2α in the same sample volume was at the borderline of sensitivity for the gas chromatographic mass spectrometric method used, with a recovery of 114% ± 19 (mean ± SEM; n = 4).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 173
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 280-282 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 70 eV and 20 eV electron ionization mass spectra of several exo-5,6-trimethylene-endo- and exo-norbor-nanols may be used in certain circumstances as an analytical tool in the identification of the individual alcohols.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 174
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 276-279 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main metabolite of prostaglandin E2 (PGE2) 13,14-dihydro-15-keto-PGE2 readily dehydrates and can subsequently form a cyclic derivative. This problem can be overcome by the immediate formation of oximes of the 9 and 15 ketones in aqueous solution followed by subsequent extraction, methylation and t-butyldimethyl silylation of the free hydroxyl groups at 11 and on the oximes. Deuterogenated 13,14-dihydro-15-keto-PGE2 is used as the internal standard and can be stored as the oxime and added with the oximating solution immediately the biological sample is obtained. The sensitivity of the method allows measurement of 2 ng of 13,14-dihydro-15-keto-PGE2 in tissue incubates. The intra-batch precision is 11.8% and the inter-batch precision for measurement of 100 ng of metabolite is 8.1%.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 175
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 287-291 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive ion fast atom bombardment mass spectra of a series of monovalent Technetium(III) cation complexes yield intense [C]+ ions and distinctive fragmentation information.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 176
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 177
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analytical procedure has been developed for the simultaneous determination of ketobemidone and its N-demethylated metabolite, norketobemidone. After isolation from plasma and re-extraction to acidic aqueous phase, the two aminophenols were extracted as ion pairs with tetrabutylammonium to dichloromethane, where derivatization with ethyl chloroformate took place. Determination was performed by gas chromatography mass spectrometry with selected ion monitoring. Ketobemidone and norketobemidone could be detected in plasma in a concentration of 1 ng ml-1 and 3 ng ml-1, respectively. Determinations were performed down to 5 ng ml-1. The relative standard deviation of the method in the analysis of 10 ng ml-1 of ketobemidone and norketobemidone, respectively, was 8% and 9% (n = 10). The absolute recovery of unconjugated ketobemidone and norketobemidone through the method at the 100 ng ml-1 level was 91% and 85%, respectively. The method was applied to the determination of ketobemidone and norketobemidone in plasma from patients given ketobemidone. The concentrations of unconjugated norketobemidone was too small to be detected.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 178
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conjugation products with glutathione (GSH) and other endogenous thiol derivatives related to the oxidative metabolism of the anticancer drug, 4′-(9-acridinlyamino) methanesulfon-m-anisidide (m-AMSA) were synthesized and characterized by field desorption mass spectrometry. The primary microsomal oxidation product of m-AMSA, m-AQDI, was prepared by MnO2 oxidation of the parent drug and reacted with equimolar GSH, cysteine, N-acetylcysteine and N-acetylcysteine methyl ester to form m-AMSA-(5′)-thiol conjugates linkedat the aniline ring, as major products. Field desorption mass spectra of the conjugates provided abundant [MH]plus; ions, and characteristic fragment ions by cleavage at the thioether bonds and at the γ-Glu-Cys linkage. The assignment of the 5′-position of the thioether linkage at the aniline ring was ascertained by 1H nuclear magnetic resonance spectra. However, the reaction of m-AQDI with increased molar amounts of thiol, and with cysteamine as a bifunctional nucleophile at equimolar amounts afforded the concurrent formation of conjugation products by nucleophilic displacement at the acridine moiety of m-AMSA. In the reaction with cysteamine, a ‘dimeric’ adduct of cysteamine linked to both the aniline and the acridine of cysteamine linked to both the aniline and the acridine moiety of moiety of m-AMSA was separated as a major product by thin-layer chromatography and identified by field desorption mass spectrometry. m-AMSA-GSH, a major biliary metabolite of m-AMSA in the rat undergoes with excess GSH in aqueous solution a thiolytic cleavage to yield S-(9-acridinyl)-GSH (ACR-GSH) and S[(4-amino-3-methoxymethanesulfonanilide-5-yl]-GSH (MSA-GSH) as established by thin-layer chromatography, reversephase high-performance liquid chromatography and mass spectral analysis. These results suggest that the formation of m-AMSA-thiol (aniline ring) v. thiolysis (acridine ring) conjugates may depend on the rate of enzymatic oxidation of m-AMSA and GSH levels in vivo, and may explain the different pattern of biliary metabolites found in previous studies.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 179
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During regulatory analysis of pesticides and industrial chemicals, compounds are frequently encountered which cannot be readily identified by gas chromatography alone on two or more stationary phases. Such incurred unknown analytical responses are examined by gas chromatography mass spectrometry, particularly if they have been shown to contain P, S, N or halogen via specific gas chromatography detectors. Seven case histories are presented to illustrate the analytical approach adopted to structurally elucidate such compounds at the ppm level. These examples demonstrate the potential complementary combination provided by low resolution electron impact and chemical ionization mass spectrometry in structural determinations.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 180
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conditions were established for analyzing as little as 5 pmol of an underivatized peptide delivered in a glycerol sample matrix as a thin film onto a gold-plated copper sample stage and then bombarded with xenon fast atoms. Calibration of the fast atom bombardment high field mass spectrometer and data system was achieved using cesium iodide/glycerol as a reference. Calibration at several accelerating potentials permitted a mass range from 393 to 5941 u. Several factors were examined that contribute to the quality of the mass spectrum: components within the glycerol such as other peptides, alkali salts, acid and reducing agents; the nature of the fast atom gas; concentration of the peptide delivered to the sample stage; and the effect of the sample stage and sample matrix on sensitivity.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 181
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Δ9-Tetrahydrocannabinol and two of its metabolites, 11-hydroxy-Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol, can be measured in a single 1-ml sample of blood, plasma, or urine by a new assay which combines a relatively rapid extraction procedure with capillary column gas chromatography and negative ion chemical ionization mass spectrometry. Deuterium-labeled analogs of each cannabinoid are added to the physiological specimen as internal standards. Two extracts are obtained from each sample: a neutral fraction containing Δ9-tetrahydrocannabinol and 11-hydroxy-Δ9-tetrahydrocannabinol, and an acid fraction containing 11-nor-9-carboxy-Δ9-tetrahydrocannabinol. The neutral fraction is derivatized by treatment with trifluoroacetic anhydride; the acid fraction is first treated with BF3-methanol followed by reaction with trifluoroacetic anhydride. Under electron-capture chemical ionization conditions the derivatized Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol give abundant molecular anions ideally suited for selected ion monitoring. The negative ion chemical ionization spectrum of the HO-THC-trifluoroacetate shows no molecular anion. Consequently, quantitation of the hydroxy metabolite is achieved by monitoring a fragment ion formed by loss of CF3CO2 from its molecular anion. The limits of reliable measurement are judged to be 0.1 ng ml-1 for 11-nor-9-carboxy-Δ9-tetrahydrocannabinol, 0.2 ng ml-1 for Δ9-tetrahydrocannabinol and 0.5 ng ml-1 for 11-hydroxy-Δ9-tetrahydrocannabinol. Four examples are given of the application of the assay to the analysis of specimens of medico-legal importance.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 182
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 334-337 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Nitrosodiethanolamine metabolism was studied in order to clarify the mechanism(s) by which this compound elicits its carcinogenic effect. Samples of 24 h urine from rats given a single dose of N-nitrosodiethanolamine were collected. Gas chromatographic thermal energy analyses showed the presence of only one compound containing the nitroso moiety besides N-nitrosodiethanolamine. This compound was identified as the acidic derivative N-(2-hydroxyethyl)-N-carboxymethylnitrosamine by comparison with an authentic standard by means of gas chromatographic mass spectrometric analysis of the trimethylsilyl or pentafluorobenzyl esters. The amount of N-(2-hydroxyethyl)-N-carboxymethylnitrosamine excreted in the 24 h urine was about 6% of the N-nitrosodiethanolamine administered.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 183
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 184
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 343-346 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the electron impact mass spectra of esters of aliphatic alcohols, a series of first field free region metastables are observed for the formation of the acylium ion, [R.CO]+, from a set of precursor ions created by fragmentation at each successive C—C bond in the aliphatic alcohol chain. The positions and intensities of these metastables are characteristic of sites of chain branching and of double bonds in the alcohol moiety.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 185
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The acid fraction from an extract of a test well sample obtained from a landfill site has been examined by capillary gas chromatography mass spectrometry, and liquid chromatography mass spectrometry. In the latter case conventional and glass-lined stainless steel microbore liquid chromatography columns were used. Desorption chemical ionization and field desorption mass spectrometry have been used to profile the major components present in the mixture. This combined approach enables a more detailed characterization of the sample to be obtained and the techniques have been found to be mutually complementary. Glass-lined stainless steel microbore columns used with a gradient system are shown to provide high quality liquid chromatographic mass spectrometric data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 186
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 347-351 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra were obtained for a series of purine and pyrimidine nucleosides in liquid chromatographic mass spectrometric experiments using a direct liquid introduction probe as interface. Separation of a mixture of adenosine, thymidine, uridine and inosine, and a mixture of hypoxanthine, xanthine, adenine, adenosine, uridine, uracil and thymidine was accomplished using gradient elution with methanol and ammonium formate as a direct liquid introduction liquid chromatographic mass spectrometric compatible solvent system.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 187
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 358-362 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Leucine enkephalin is measured in canine spinal cord tissue in a structurally unambiguous manner. A rapid tissue procurement procedure minimizes enkephalin metabolism. High-performance liquid chromatography purification of brain neuropeptides is followed by field desorption mass spectrometric measurement of leucine enkephalin in spinal cord tissue extracts. Quantification is performed at the 70 ng (126 pmol) g-1 of wet weight tissue, or 70 parts per billion level. The higher homolog of leucine enkephalin, 2ala-leucine enkephalin, is utilized as internal standard. Straight-line statistics are obtained for a series of samples to which a peptide standard is added.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 188
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 363-368 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral fragmentation behaviour of some labda-7,14-dien-13(R)-ol monoglycosides has been studied. Mass spectra of O-isopropylidine derivatives of the glycosides have been determined to distinguish the isomeric sugar moieties containing rhamnopyranose, fucopyranose and 6-deoxyidopyranose, respectively. The main fragment ions of the sugar moieties were investigated with the aid of deuterium labelling and high resolution mass measurement.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 189
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 352-357 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analytical methodology of 1,2,3,4,5,6-hexachlorocyclohexane isomers residing in an aquatic environment was investigated with gas chromatography electron impact mass spectrometry selected ion monitoring as the determinative technique. An extraction method with a macroreticular Amberlite XAD-2 resin column was successfully developed and the extract was subjected to the gas chromatography electron impact mass spectrometry selected ion monitoring system. Ions at m/z 219 [M—HCl2+2]+· from residual 1,2,3,4,5,6-hexachlorocyclohexane isomers and m/z 224 [M—2HCl2+2]+· from dual laboratory-synthesized deuterated internal standards were monitored for the estimation. Linearities of individual 1,2,3,4,5,6-hexachlorocyclohexane isomers with gas chromatography electron impact mass spectrometry selected ion monitoring were much wider than those with gas chromatography electron capture detection, and it could be said that dilution or concentration of the sample extract was commonly unnecessary. In addition, carrier effects of deuterated internal standards with representative water samples and selectivity of the method in comparison with gas chromatography electron capture detection were clearly shown. In field experiments, total 1,2,3,4,5,6-hexachlorocyclohexane levels were from 166.54 to 7.40 parts per trillion (ng L-1).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 190
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 369-376 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simultaneous acquisition of both positive ion and negative ion data under chemical ionization mass spectrometric conditions can aid in the confirmation of assignments made by electron impact gas chromatography mass spectrometry or electron capture gas chromatography. Pulsed positive ion negative ion chemical ionization mass spectrometry coupled with fused-silica capillary column gas chromatographic methods is shown to be useful in environmental and hazardous waste sample analysis. The chemical ionization conditions which maximize sensitivity and the amount of molecular ion information for the priority pollutants are presented. Replicates of response factors for these compounds show good precision. Saturation is observed about 10 ng for those pesticides which give linear responses from 50 pg to 1-10 ng.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 191
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 382-386 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment mass spectra of a series of phospholipids are reported. Abundant molecular ions are noted together with fragment ions which provide structural information about the acyl and phosphate ester groupings. The application of fast atom bombardment mass spectrometry to the analysis of complex phospholipid(phosphatidylcholine) mixtures is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 192
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identification of components in the essential oil of Cannabis sativa L. is accomplished by combining the information of molecular weight, functional group and retention index. The molecular weight of individual substances eluting from a capillary column is determined by negative ion chemical ionization. The reactant ion OH- produces [M—H]- ions by proton abstraction. The RCOO unit present in esters is converted into the RCOO- ion by a nucleophilic attack by the OH- ion upon the ester function, which offers a simple identification of the acid part of an ester.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 193
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Under negative ionization conditions, nominal mass calibration of the fast atom bombardment high field mass spectrometer and data system was accomplished using cesium iodide/glycerol as a reference. Mass calibration at -8 kV accelerating potential extends from m/z 387 to m/z 2170 using xenon fast atoms. Negative xenon FAB mass spectra for human angiotensin I and human gastrin I complement their positive fast atom bombardment spectra. Negative xenon fast atom bombardment spectra of underivatized peptides exhibit molecular proton-abstracted ion envelopes and structurally significant fragment ions. Peptide mixture analysis under negative xenon fast atom bombardment reveals peptide molecular ion envelopes of higher relative intensities than under positive xenon fast atom bombardment.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 194
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983) 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 195
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 394-394 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 196
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 197
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 395-398 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capillary gas chromatographic mass spectrometric method for the quantification of warfarin and its known metabolites from microsomal incubations is described. Deuterium labelled 4′, 6-, 7- and 8-hydroxy warfarins are used as internal standards and the method has detection limits of 1 ng ml-1 with 20 ng ml-1 being the lower limit for accurate quantification.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 198
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 399-403 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enolsilylation of prostaglandins E1 and E2 as well as their 11-desoxyanalogues and the corresponding methyl esters by a mixture of N,O-bis-(trimethylsilyl)acetamide-piperidine (1:1) results in trimethylsilyl ether derivatives of Δ8(9)-enol forms contaminated by c.10% Δ9(10)-enol derivatives. Isomeric PGE2 9-enol-trimethylsilyl ether derivatives are separable by capillary gas-liquid chromatography and their mass spectra show different fragmentations of the side chains diagnostic for the above structures. Therefore, the use of 9-enol-trimethylsilyl ethers for prostaglandins E analysis in biological fluids could lead to formation of the two peaks in the gas chromatogram and moreover does not discriminate between common and 8-iso-prostaglandins E.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 199
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive and specific method for the quantitative determination of a new antitumor agent,l-(2-chloroethyl)-3-(2,6-dioxo-3-piperidyl)-1-nitrosourea, (PCNU) has been developed for the analysis of plasma. This assay involves extraction of the plasma sample, separation of the drug by thin-layer chromatography and mass spectrometric detection of the negative ions derived from the unchanged drug and its 2H4-labeled analog. Ion current profile peaks are obtained when drug samples are introduced into the heated source using a desorption chemical ionization probe. Detection limits are below 1.0 ng ml-1 of plasma. This method has been applied to determine the in vitro rate of decomposition of PCNU in plasma and the plasma clearance of this drug from a cancer patient.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 200
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sixteen peptides ranging in molecular weights from 858 to 5729 were examined under positive ionization fast atom bombardment conditions employing a high field magnet mass spectrometer and data system. The contributions of the polyisotopic elements to the molecular protonated ion envelope become important in the interpretation of the data at higher mass. For masses less than 2000 u, the most abundant ion within this envelope is the monoisotopic molecular protonated ion. Above 2000 u, the most abundant ion in the envelope is a polyisotopic molecular protonated ion. Characterization of the peptide requires identification of both the molecular protonated ion envelope and significant fragment ions. Partial spectra displaying both the molecular ion and significant fragment ions are presented for mastoparan (mol. wt = 1478), somatostatin (mol. wt = 1637), bovine parathyroid hormone (1-34) (mol. wt = 4106), and bovine insulin (mol. wt = 5729). A partial spectrum for bovine ribonuclease A (mol. wt = 13673) displayed significant fragment ions that identified the protein. The types of fragment ions included those that indicated the amino acid sequence and the location of disulfide bonds. The abundance of these ions appears to be influenced by the characteristics of the noble gas fast atom beam and the sample matrix.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...