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  • Analytical Chemistry and Spectroscopy  (5,640)
  • General Chemistry  (5,085)
  • GEOPHYSICS  (4,117)
  • 1985-1989  (14,842)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 601-608 
    ISSN: 0886-9383
    Keywords: Gas phase flow injection analysis ; Membrane-differentiated analysis ; Multicomponent determinations ; Successive linear regression ; Successive regression in fiduciary region ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A membrane-discriminated gas phase analyzer is proposed for multicomponent determinations. Nitrogen gas flows countercurrent through outer and inner channels in a tube-in-tube arrangement. The only communication between the two channels occurs through a 500 μm aperture covered by a porous PTFE membrane. A mixture of organic compounds (up to four components) is injected into the inner channel by a heated backflushed injector and the sample components diffusing into the outer channel are monitored by a flame ionization detector (FID). A calibration set, consisting of pure components, binary, ternary and quaternary mixtures (a total of 64 samples), provides the known data base: temporal profiles of the FID output as a function of sample composition. Although the overall response behavior is not a linearly additive function of individual analyte concentrations, the use of successive inverse multiple linear regression (while continually altering the choice of the calibration samples considered for the forward regression, on the basis of the most recent values of the predicted unknown sample composition) is shown to yield analytical results for unknown samples that are in good agreement with their true values.
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  • 2
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 609-609 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 3
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 39-42 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of gas chromatography/mass spectrometry to three thermally labile phenylurea pesticides is reported. Using alcohols as solvents the decomposition of the pesticides is followed by a reaction in which esters of N-(3,4-dichlorophenyl)carbamic acid are formed. As these reactions occur during the gas chromatographic analysis, it is the esters which are identified in the mass spectrometer. The methyl ester is itself a pesticide so an erroneous conclusion about the original pesticide could be reached when methanol is the solvent.
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  • 4
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 43-45 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ions produced by 252Cf plasma desorption are detected by Fourier transform ion cyclotron resonance techniques. Results for CsI and N,N,N-trimethyl-p-aminophenolate iodide show the feasibility of the technique with high resolution (up to 11 000 at m/z 23) and good signal-to-noise ratio (up to 726).
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  • 5
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 47-48 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 6
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 49-50 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 7
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 51-51 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 53-61 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fast atom bombardment positive ion mass spectra and the [M + H]+ collisional activation spectra of t-butyloxycarbonyl protected peptides and the unprotected analogues have been compared. It is concluded that sequence information, especially from the collisional activation spectra, can better be derived from the underivatized peptides than from the BOC-peptides.
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  • 9
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 229-233 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The constant B2E linked scan is shown to be an excellent tool for the profiling of biogenic amines in wine samples. The fragment ion at m/z 169 of the dansylated amines is used for the precursor ion search in combination with direct sample evaporation. Besides the profile a semi-quantification may be achieved when using suitable amines as internal standards with standard deviations of 12-17%. More accurate results with standard deviations of 3-5% are obtained when using deuterated analogues as internal standards. Both methods are applied to the analysis of biogenic amines in synthetic mixtures and actual wine samples.
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  • 10
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 241-246 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 252-Californium plasma desorption mass spectrometry was applied to the study of five different classes of phospholipids namely phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine and phosphatidylinositol. Positive and negative ion spectra were compared to spectra obtained using other ionization techniques. Plasma desorption mass spectra provide useful information on the molecular weight of compounds from all classes, particularly in the case of phosphatidylserine - a class that has failed to show satisfactory quasimolecular ions with either Fast atom bombardment, FAB or Field desorption, FD. The observed fragmentation is also indicative of the structure of the studied compounds.
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  • 11
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new quantitative assay for the determination of S3341, an alpha-2 agonist antihypertensive drug, has been developed using combined gas chromatography-negative ion chemical ionization mass spectrometry. The [M]-. ions from TFA derivatives of S3341 (m/z 276) and the internal standard (2H4)S3341 (m/z 280) are monitored simultaneously by selected ion monitoring. For S3341 concentrations ranging from the limit of detection (0.2 ng ml-1 using 1 ml of plasma) to 5 ng ml-1, the average assay precision (CV) is approximately 7% while the average assay accuracy (percentage of error) is 4%. Validation of the day-to-day precision and accuracy was realized after analysing control plasma samples (n = 295) concurrently with the biological samples collected during the pharmacokinetic studies conducted over 15 months. The average day-to-day precision (CV) and accuracy (percentage of error) are 10% and 6% respectively, thus indicating that this assay procedure routinely provides reliable analytical data.
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  • 12
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Positive ion fast atom bombardment mass spectrometric sensitivities of seven amino acids and the corresponding di-isopropylphosphorylated derivatives were carefully compared. Results showed that an improvement in sensitivity by factors of 4-29, mostly above 10, were achieved after the derivatization. The chemical noise derived from glycerol matrix was also greatly reduced by this derivatization.
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  • 13
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for the quantitative determination of cholesterol and three of its major oxidative metabolites (the 5α,6α-epoxide, the 3β,5α,6β-triol, and the 5β,6β-epoxide) in a single sample of human breast fluid (2-50 μl), using gas chromatography/mass spectrometry with selected ion monitoring. High specificity and reliable quantification is achieved by the use of the inverse stable isotope dilution method, employing deuterium-labeled variants of the compounds as internal standards.
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  • 14
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes a method for simultaneous determination of the kinetics of the three major bile acids in man using (2,2,4,4-2H4) deoxycholic acid, (24-13C) cholic acid and (24-13C) chenodeoxycholic acid. The gas chromatographic/mass spectrometric-selected ion monitoring technique used provided complete separation of deoxycholic acid, cholic acid and chenodeoxycholic acid, which permitted simultaneous measurement of isotope ratios for all three bile acids. Since measurement of all three pool sizes and fractional turnover rates in a single experiment requires different isotopic labels for deoxycholic acid and cholic acid, we investigated the in vivo stability and applicability of (2,2,4,4-2H4) deoxycholic acid as a stable isotope marker for isotope dilution studies in man. No consistent differences were observed between deoxycholic acid pool sizes and fractional turnover rates determined in serum samples after administration of (2,2,4,4-2H4) deoxycholic acid and (24-13C) deoxycholic acid. Simultaneous administration of (2,2,4,4-2H4) deoxycholic acid (24-13C) cholic acid and (24-13C) chenodeoxycholic acid and isotope ratio measurements in serum permitted determination of pool sizes and fractional turnover rates of the three major bile acid and the 7α-dehydroxylation fraction. Pool sizes, fractional turnover rates and synthesis rates (input rates) agreed well with data obtained previously with (24-13C) labels in independent studies.
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  • 15
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Urines of two children with 17α-hydroxylase deficiency contained a number of 5-pregnane- and pregnenediols, -triols and -tetrols with a hydroxy or oxo group in position 11 of the steroid ring. They are formed mainly from progesterone via 11-hydroxyprogesterone, pregnanolone and corticosterone, respectively, or from pregnenolone. Three metabolites not previously described, 16-hydroxypregnenolone, 6,21-dihydroxypregnanediol and 6-hydroxytetrahydrocorticosterone, were identified.
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  • 16
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 649-651 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identified urinary metabolites of male rats exposed to indan are: 1- and 2-indanone; 1-, 2- and 5-indanol; 2-and 3-hydroxyl-1-indanone; and cis- and trans-indan-1,2-diol. Indan causes kidney damage in male rats in a manner similar to the cyclic hydrocarbons cis- and trans-decalin and JP-10. Lesions produced by indan occur only in male rats and not in female or control rats.
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  • 17
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    Biological Mass Spectrometry 14 (1987), S. 663-668 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic acidaemias are an important part of inborn errors of metabolism. The biochemical diagnosis is based on gas chromatographic/mass spectrometric identification of urinary organic acids. Since 1973 we have used gas chromatographic analysis of the methyl esters of urinary organic acids. Mass spectral identification was performed only when an abnormal gas chromatographic profile was suspected. In 1983 we introduced routine gas chromatographic/mass spectrometric analysis organic acids. More than 1500 urine samples from 1000 children have been analysed and we encountered more than 40 abnormal profiles: 18 classical organic acidaemias (propionic, methyl-malonic, isovaleric, glutaric type I and 3-hydroxy-3-methyl glutaric acidaemias); 6 aminoacidopathies with excretion of branched chain keto acids (leucinosis) or succinylacetone (tyrosinosis type I); 14 massive dicarboxylic acidurias with excretion of suberyl and hexanoyl glycine and deficiency of the medium chain acyl CoA dehydrogenase in four patients. The use of gas chromatography/mass spectrometry routinely allows the identification of abnormal metabolites excreted in small amounts: β-methyl-crotonyl glycine indicative of biotin deficiency: γ-hydroxybutyric acid; and 3-methyl-glutaconic + 3-methy-glutaric acid is in a 3-methyl-glutaconic aciduria type II. Abnormal profiles due to metabolites of drugs as valproate, salicylate and barbiturate can be recognized immediately. This simple gas chromatographic/mass spectrometric system can lead to diagnosis, in one day, of rare but severe diseases needing a specific and early treatment.
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  • 18
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of serum cortisol by thermospray liquid chromatography/mass spectrometry (LC/MS) has been assessed. The method incorporates stable isotope dilution and innumoadsorption extraction. [M + H]+ ions are monitored during LC/MS. The within-assay reproducibility is satisfactory (coefficient of variation 7% at a concentration of 190 ng ml-1), though inferior to that achieved with the (more lengthy) procedure of gas chromatography/mass spectrometry (GC/MS). Satisfactory agreement between LC/MS (y) and GC/MS (x) data was observed (y = 0.934x + 12.4 ng ml-1; r = 0.968; n = 14). It is concluded that the generation of precise reference data for the assessment of routine cortisol assays is at present better achieved by GC/MS. LC/MS, however, provides satisfactory quantitative data via a more simple and rapid method.
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  • 19
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    Biological Mass Spectrometry 14 (1987), S. 737-738 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 20
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rapid and simultaneous quantification of 11 prostanoids has been carried out with a short-capillary gas chromatograph and negative ion chemical ionization (ammonia) mass spectrometer.The methoxime-trimethylsilyl ether-pentafluorobenzyl esters (MO-TMS-PFB) of nine prostanoids, PGA1, PGA2, PGB1, PGB2, PGD2, PGE1, PGE2, 6-oxo-PGF1α and TXB2 and the TMS-PFB of two prostanoids, PGF1α and PGF2α, were separated in less than 5.5 min on a bonded OV-1 capillary column 0.25 mm i.d. × 6 m (0.15 μm thickness) using hydrogen as a carrier gas. PGD2, PGE2, PGF2α, 6-oxo-PGF1α and TXB2 were quantified up to 2.5 fmol injected (0.1 pmol derivatized) and both PGA2 and PGB2 up to 25 fmol injected (1 pmol derivatized).In order to maintain the stability of the prostanoids containing a carbonyl group, such as TXB2 during the purification and derivatization steps of biological materials, methyl acetate was used in place of methyl formate as an eluant for Sep-Pak C18 purification.Normal human embryonic lung fibroblasts W138 (5.63 × 105 cells in a log phase) produced: PGA2 15.28, PGB2 13.48, PGD2 7.95, PGE1 2.62, PGE2 177.76, PGF2α 25.14, 6-oxo-PGF1α 27.33 and TXB2 61.00 pmol in 10 ml of Eagle minimal essential medium.
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  • 21
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    Biological Mass Spectrometry 15 (1988), S. 57-62 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium borodeuteride treatment of urine expected to have large concentrations of pyruvic and acetoacetic acids produces lactic and 3-hydroxybutyric acids labelled with deuterium. Mass fragmentographic techniques applied to the trimethylsilyated extract of the urine spiked with more extensively labelled analogues as internal standards permit the reliable determination of lactic, pyruvic, 3-hydroxybutyric and acetoacetic acids in a single analysis.
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  • 22
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    Biological Mass Spectrometry 15 (1988), S. 79-87 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ammonia and deuterated ammonia chemical ionization (CI) mass spectra and collisionally activated dissociation (CAD) mass spectra of ammonium adduct ions are presented for ten trichothecenes. The samples were introduced by direct exposure probe. Effects of ion source temperature and pressure on the ammonia CI gas plasma and the formation of the ammonium adduct ion were studied. The CI conditions were optimized to produce a maximal yield for the ammonium adduct ion of trichothecenes, i.e. the parent ion for tandem mass spectral analysis. Besides source temperature and pressure, proton affinity and the stability of the ammonium adduct ion affect the relative abundance ratio of [M + H]+:[M + NH4]+ in ammonia CI and CAD mass spectra. The ratio [M + H]+:[M + NH4]+, and hence the stability of the ammonium adduct ion, are largely determined by the functional groups (hydroxy, carbonyl, acetoxy, and isovaleroyloxy) and their location in the trichothecene nucleus. The most abundant fragment ions in the ammonia CI spectra and the most abundant daughter ions in the CAD spectra of the ammonium adduct ions are formed by the losses of ammonia and functional groups as neutrals in various combinations.
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  • 23
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of an aminoxyl and the corresponding hydroxylamine with silylating agents is studied in detail. The gas chromatographic/mass spectrometric analysis of the products is consistent with the production of an unsaturated product when an alkyl group with exchangeable hydrogens is attached to the nitrone group. The structure of this compound is confirmed by deuteration. It is concluded that aminoxyls themselves do not derivatize wth silylating agents.
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  • 24
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron impact mass spectra of methyl ester/trimethylsilyl ether derivatives of prostaglandin F2α and methyl ester/methoxime/trimethylsilyl ether derivatives of prostaglandin E2, prostaglandin D2, 6-oxo-prostaglandin F1α and 2,3-dinor-6-oxo-prostaglandin F1α are presented. Most of the prostaglandins studied have additionally been 2H-labelled at different sites in order to assign the corresponding fragment ions. Collisionally activated decomposition mass spectra of the most intense parent ions in the high-mass region were taken. High-intensity, prostaglandin-characteristic daughter fragments will allow a reliable quantification of prostaglandins in biological fluids and a reduction of sample clean-up.
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  • 25
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    Biological Mass Spectrometry 15 (1988), S. 157-161 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic/mass spectrometric assay for quantifying two catechol estrogens, 2-hydroxyestradiol and 4-hydroxyestradiol, in microsomal preparations is described. The assay employs deuterium-labeled analogs of the catechol estrogens as internal standards and permits quantification of catechol estrogens, in microsomal incubations, at low (1-2) μM concentrations. The compounds are analyzed as their trimethylsilyl derivatives following separation by capillary gas chromatography.
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  • 26
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    Biological Mass Spectrometry 15 (1988), S. 175-178 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly sensitive (subpicomole level) and structural specific method for the analysis of arachidonic acid esterified to complex glycerophospholipids has been developed using combined capillary gas chromatography and mass spectrometry. The methodology is based upon the formation of the pentafluorobenzyl ester of arachidonic acid, which is efficiently ionized using electron capture negative ion chemical ionization conditions to yield an abundant carboxylate anion at m/z 301. Quantification is carried out following hydrolysis of the complex glycerophospholipid in the presence of a known amount of (2H8) araachidonic acid. The use of this method is illustrated by the quantification of arachidonic acid within the glycerophospholipid classes isolated from resident peritoneal macrophage cells isolated from HS mice.
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  • 27
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    Biological Mass Spectrometry 15 (1988), S. 185-191 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Under chemical ionization conditions, satratoxins preferentially produce negatively charged molecular ions (M-·) over the positively charged protonated molecules. Collisionally activated dissociation of the M-· ions resulted in daughter ions and neutral losses which were characteristic of the macrocyclic ester bridges. Direct tandem mass spectrometric methods of analyses wee developed and applied for the detection and quantification of satratoxins in Stachybotrys atra fermentation broths. Minimum detectable levels for satratoxin standards were 5 pg. A synthetically modified macrocyclic trichothecene, 8-ketoverrucarin A, was used as an internal standard for the quantification of satratoxins in fermentation samples.
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  • 28
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper discusses the possible advantages of thermospray liquid chromatography/tandem mass spectrometry LC/MS/MS for metabolic mapping. The technique was applied to the study of the metabolism of zolpidem, a new hypnotic with an imidazo-pyridine moiety. When compared to other chromatographic/mass spectrometric-based techniques, reversed phase high-performance liquid chromatography coupled with thermospray LC/MS/MS appears to be the fastest method available today for elucidation of unknown metabolic structures, since it allows identification by direct injection of concentrated urine. However, it was noted during the thermospray process that loss of formaldehyde from a hydroxymethyl amide metabolite occurred. This degradation was not observed when this metabolite was analysed by gas chromatography/mass spectrometry following trimethylsilylation.
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  • 29
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    Biological Mass Spectrometry 15 (1988), S. 257-263 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photodynamic therapy (PDT) involves the treatment of tumor tissue with a photosensitizer and light to effect the delineation and/or eradication of the tumor. PDT is a two step process: (1) incorporation of photosensitizer into the cell where it must be retained by tumors in vivo; and (2) illumination of the tumor cell with light to effect cell death. Hematoporphyrin derivative (HPD) is a complex mixture of porphyrins currently used for PDT in the clinical setting. Hematoporphyrin-based oligomers of up to five subunits were determined using fast atom bombardment mass spectrometry of the high-molecular-weight fraction of the drug. Reduction of this fraction with LiAlH4 permitted determination of the covalent bond linking the monomers in these oligoporphyrins. Application of these analytical procedures to the determination of the composition of different preparations of HPD will be described.
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  • 30
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    Biological Mass Spectrometry 15 (1988), S. 291-293 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the process of developing a high-sensitivity negative chemical ionization gas chromatographic/mass spectrometric assay for brain and cerebrospinal fluid (CSF) levels of quinolinic acid (QUIN, 2,3-pyridine dicarboxylic acid), (18O4)QUIN was prepared. Its properties as an internal standard were compared with those of the structural isomer 2,4-pyridine decarboxylic acid (2,4-PDC) previously used by others. All oxygen atoms in QUIN were labeled by heating in 3N HCl/(18O)water for 48 h at 80°C. Back-exchange of (18O4)QUIN was prevented during derivatization to an electron-capturing dihexafluoropropanol ester by using trifluoroacetylimidazole as catalyst instead of perfluroacyl anhydrides. When mixtures of QUIN and (18O4)QUIN and/or 2,4-PDC were followed through a procedure to isolate and quantify brain and CSF QUIN, the variability in the ratio of QUIN:2,4-PDC was greater than for QUIN:(18O)QUIN. We conclude that (18O)QUIN is the preferred internal standard in gas chromatographic/mass spectrometric quantification of brain and CSF QUIN, and that (18O)-labeled carboxylic acids may be esterified effectively without back-exchange using acylimidazole reagents.
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  • 31
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    Biological Mass Spectrometry 15 (1988), S. 305-310 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polycyclic peptide antibiotic, Nisin, has been analysed by plasma desorption mass spectrometry using two different sample preparation techniques and two versions of the commercial plasma desorption mass spectrometer, and a prototype with high resolving power. The spectra obtained allow identification of a major component and two minor analogues. Extensive fragmentation is observed in samples prepared by the electrospray technique, whereas only ions indicating the molecular weight are produced when the sample is adsorbed on nitrocellulose.
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  • 32
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    Biological Mass Spectrometry 18 (1989), S. 174-176 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plasma levels and urinary excretion of mevalonate were reported to be correlated with cholesterol biosynthesis. Evaluation of mevalonate concentration in plasma and urine represents therefore a non-invasive method for studying the modifications of cholesterol synthesis. A method is described here by wich mevalonate in plasma and urine is determined by the selected ion monitoring technique after extraction as mevalonolactone and conversion into the trimethylsilyl ether. Linear responses were obtained in the evaluation of mevalonate added to plasma in the 10-100 ng/ml (r 〉 0.995) and to urine in the 50-1000 ng/ml concentration ranges, respectively. Identity of mevalonate in plasma and urine was confirmed by high-resolution mass spectrometry.
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  • 33
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment (FAB) mass spectrometry was used to characterize the pyochelin complexes of iron and zinc. Ferripyochelin readily forms the [M + H]+ and [2M + H]+ ions in a glycerol matrix. The molecular ion was 2.5 fold more abundant when acetic acid was present. Iron was shown to be present in the iron-pyochelin complex as the ferric ion by wet chemical methods. Differentiation between ferric and ferrous ions by FAB was not successful owing to the FAB reducing environment. Ferric ions were reduced by FAB to ferrous ions in the following model salts - ferric chloride, ferric nitrate and ferric sulfate - when dissolved in either glycerol, thioglycerol or the magic bullet matrix. Ferric and ferrous chloride salts gave virtually identical spectra with a glycerol/acetic acid matrix. Zinc-pyochelin readily forms the [M + H]+ and [2M + H]+ ions, but only when acetic acid was present in the glycerol matrix. The FAB mass spectrum of zinc-pyochelin exhibited various fragmentations which can be used in structural analysis. Linked-scan at constant B/E and accurate mass data were used to characterize the fragmentations of the zinc-pyochelin complex. Metastable analysis allowed the fragmentation pathway of zinc-pyochelin to be determined.
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  • 34
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    Biological Mass Spectrometry 18 (1989), S. 207-217 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact (EI) mass spectra of 2,6-di-tert-butyl-4-methylphenol (BHT) and certain of its alteration products are described in detail. Accurate mass measurements confirm the elemental compositions of important fragment ions in the EI spectra. Collisionally activated mass spectra are also used to study fragmentation and suggest common ion structures. The reference spectra provide the basis for identifying various alteration products of BHT by capillary gas chromatography/mass spectrometry (GC/MS) without the necessity of isolating individual components. Application of GC/MS is made to three studies: (i) pyrolysis of hydroperoxy-BHT as a potential pathway to alteration products in food; (ii) GC/MS pyrolysis of hydroperoxy-BHT as a model study; and (iii) alteration of BHT in ethanol/water as a food-simulating solvent.
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  • 35
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    Biological Mass Spectrometry 18 (1989), S. 363-372 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The MI and CA spectra of selected positive and negative ions generated by fast atom bombardment (FAB) of the stereoisomeric aldohexoses can be used to differentiate among these isomers, without prior derivatization or addition of other substances. The main fragmentation routes were traced and compared to those of some 2- and 6-deoxyaldohexoses, which appeared to be suitable model compounds. In both positive and negative ion FAB mass spectrometry, the OH group at the C-2 position plays an important role in the fragmentation reactions of the pseudomolecular [M + glycerol + H]+ and [M - H]- ions.
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  • 36
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    Biological Mass Spectrometry 18 (1989), S. 387-393 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chicken intestinal calbindin-D28k is an intracellular protein which is believed to have a fundamental role in vitamin D-mediated transport of calcium. A mapping approach based on 252Cf plasma desorption mass spectrometry (PD mapping) was used to screen the DNA-deduced sequence of calbindin-D28k for sequence changes and posttranslational modifications. In the PD mapping experiment, purified calbindin-D28k was cleaved with cyanogen bromide and the resulting peptides were subjected to PD mass spectrometric analysis either as a mixture or as high-performance liquid chromatography isolated fractions. The DNA-derived primary structure of calbindin-D28k was confirmed by rapid PD mass spectral identification of the CNBr peptide fragments, and the nature of the N-terminal blocking group was readily determined to be an acetyl group. The relatively non-destructive nature of the PD mass spectrometric analysis allowed the mapping of the N-terminal peptide through an additional in situ V8 protease enzymatic reaction.
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  • 37
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A current limitation in the use of fast atom bombardment (FAB) mass spectrometric mapping of peptide mixtures, derived from enzymic digestion of proteins, is that most of the hydrophilic peptides are not observed. However, it has been demonstrated from previous work that esterification of the peptide mixture results in the detection of almost all peptides in FAB mass spectrometry. This strategy of FAB mapping was applied to the protein actinidin, isolated from an Italian variety of Actinidia chinensis. Two of the 12 tryptic peptides in FAB mass spectrometry did not exhibit molecular ions predicted from the known sequence of actinidin isolated from the New Zealand variety of A. chinensis. The two peptides were isolated by high-performance liquid chromatography, subjected to Staphylococcus aureus V8 protease digestion and sequenced by gas-phase microsequencing. Nine changes in amino acid composition were detected using the rapid and powerful combination of FAB mass spectrometric mapping and gas-phase microsequencing.
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  • 38
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of 17α-methyl-17β-hydroxy-2-oxa-5α-androstan-3-one (oxandrolone) in man has been investigated by gas chromatography/mass spectrometry. After oral administration of a 10 mg dose to man, five metabolites were detected in the free fraction of the urinary samples. Oxandrolone, the major compound excreted in urine, was detected within 72 h after administration. During this period 35.8 and 8.4% of the administered dose was excreted as unchanged oxandrolone and 17-epioxandrolone, respectively. In addition, minute amounts of 16α- and 16β- hydroxyoxandrolone and a δ-hydroxy acid resulting from the hydrolysis of the lactone group of oxandrolone were detected in the urine samples 8-60 h after administration. Furthermore, the susceptibility of oxandrolone to hydrolysis was investigated under several pH conditions. Extraction and fractionation of steroidal metabolites was achieved by using C18 and silica Sep Pak™ chromatography. The mass spectra of the metabolites are presented and major fragmentation pathways discussed.
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  • 39
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An increasing amount of evidence is accumulating to support the proposal that steroidogenesis can occur by a sesterterpene pathway as well as the cholesterol pathway. Key intermediates on the sesterterpene pathway are 23,24-dinor-5-cholen-3β-ol (guneribol) and some of its metabolites, e.g. 23,24-dinor-4-cholen-3-one (guneribone). It has been reported that these intermediates are biosynthesized and converted to steroid hormones by a range of endocrine tissues in vitro. Monitoring the pentafluorobenzyloxime derivatives by negative ion chemical ionization mass spectrometry in the electron capture mode provided evidence for the presence of guneribone in extracts of bovine testicular and human adrenal tumour tissue. Complementary evidence was obtained from gas chromatographic/tandem mass spectrometric data generated on a triple-quadrupole instrument by monitoring daughter ions (in the multiple ion detection, MID mode) of the molecular anion of derivatized guneribone in both standards and tissue extracts. The present findings that sesterterpene pathway intermediates are present as endogenous compounds in tissue extracts, together with the previously reported radiochemical data, give further support to the sesterterpene pathway hypothesis.
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  • 40
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic/mass spectrometric analytical procedure is described to determine glycols in plasma as cyclic butyl boronate esters. The method, involving a pre-deproteinization step, required only 0.25 ml of plasma and a short time (20 min) to react with the derivatizing agent (butyl boronic acid). The gas chromatographic separation on a CP Sil 8 CB silica capillary column coupled to a mass detector assured a complete identification of the compounds. The analytical recoveries (〉95%) with low coefficient of variation (4-11%) assured the feasibility of the method over a concentration range from 5 to 1000 μg ml-1 for each glycol. The lower detection limits, namely 1-5 μg ml-1, confirmed the sensitivity of the method.
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  • 41
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    Biological Mass Spectrometry 18 (1989), S. 603-612 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of tetradeuterated 10-methylundecanoic acid, dideuterated tetracos-2-enoic acid, (1-14C)pristanic acid and (1-14C)tetracos-2-enoic acid using the Favorsky rearrangement are described. They will be used for studies of long-chain fatty acid metabolism in patients. The positions of isotope labelling were determined by mass spectrometry.
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  • 42
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    Biological Mass Spectrometry 18 (1989), S. 617-619 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Negative ion fast atom bombardment mass spectrometry is used to verify the sequence of oligodeoxyribonucleotides containing a single modified nucleotide. Both the position in the sequence and the molecular weight of the modified nucleotide can be determined from the 3′ and 5′-phosphate sequence ions which are prominent in the mass spectrum.
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  • 43
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    Biological Mass Spectrometry 18 (1989), S. 620-623 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of sulphonyl hydrazones and derivatives have been synthesized and tested for biological activity as pesticides during the crop protection research programme at the Hatfield Polytechnic. A recent comparative ionization study of some of these compounds using electron impact (EI), fast atom bombardment (FAB) and various chemical ionization methods showed FAB mass spectrometry to be the optimum technique to use in terms of molecular weight information obtained. This study compares the FAB mass spectral data in positive and negative ion mode using an alternating positive and negative ion detection system.
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  • 44
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermospray liquid chromatography/mass spectrometry (LC/MS) interface has had a major impact on the direct analysis of the metabolic fate of xenobiotics in complex biological media. This paper outlines the rapidity and power of the LC/MS approach, and shows how detailed structural information can be obtained without recourse to individual compound isolation. This provides a great saving in time and effort. The additional specificity of liquid chromatography/tandem mass spectrometry is highlighted in identifying the sites of metabolic transformation. The ability to handle biological samples with little or no clean-up using wide high-performance liquid chromatographic gradients is a key feature of the success of this methodology.
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  • 45
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    Biological Mass Spectrometry 18 (1989), S. 629-636 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several populations of Achillea species were collected from Hungarian localities. The characteristic composition cf the essential oils of almost 220 populations were determined by gas chromatography/mass spectrometry. The main component of Achillea asplenifolia, A. setacea and A. collina oils is chamazulene, with a molecular mass of 184. The composition of some A. setacea is different: instead of chamazulene it contains a significant amount of farnesene. Oils of A. distans, A. crithmifolia, A. nobilis, A. pannonica and A. ochroleuca contain some different and specific compounds instead of chamazulene. During the analysis of many essential oils, we found some very interesting differences within species originating from another geographical area.
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  • 46
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron impact mass spectra of methyl ester/methoxime/trimethylsilyl ether derivatives of thromboxane B2 (TxB2) and 2,3-dinor-TxB2 and methyl ester/trimethylsilyl ether derivative of 11-dehydro-TxB2 are presented. Additionally, the derivatives of (2H4)-thromboxanes and methyl ester (2H3)-methoxime/trimethylsilyl ether derivatives of TxB2 and 2,3-dinor-TxB2 and (2H3)-methyl ester/trimethylsilyl ether derivative of 11-dehydro-TxB2 were investigated. Collision-induced dissociation mass spectra of the most intense parent ion in the high-mass region were taken. Collisionally activated decomposition mass spectra of the [C(12)-C(20)]+ ion of TxB2 and 2,3-dinor-TxB2 show an intense but not specific daughter ion, whereas the collison-induced dissociation mass spectrum of the [M - (C(16)-C(20)]+ ion of 11-dehydro-TxB2 results in the formation of numerous daughter ions.
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  • 47
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deficiency of biotin at the tissue level can be assessed indirectly by measuring the urinary excretion of 3-hydroxyisovaleric acid. This paper describes the application of an improved method of quantifying urinary 3-hydroxyisovaleric acid using unlabeled and uniformly deuterated 3-hydroxyisovaleric acid. These compounds were synthesized by a modification of the lithioacetic acid method for generation of beta-hydroxy acids. Elemental analysis, nuclear magnetic resonance, gas chromatographic and gas chromatographic/mass spectrometric data demonstrated that the compounds are greater than 95% pure. Mass spectrometry confirmed the identity of the unlabeled compound, demonstrated that the deuterated compound is uniformly labeled, and offered insight into the pattern of mass fragmentation. The method for determination of the concentration of 3-hydroxyisovaleric acid in rat urine uses gas chromatographic/mass spectrometric quantification of the di-trimethylsilyl derivative with the deuterated compound as the internal standard. Results provide evidence that this method is more accurate than a previously published method that did not utilize the unlabeled and deuterated standards.
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  • 48
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of deutrated cortisol (9,12,12,-2H)cortisol, (2H3-F) was compared to that of radioactive cortisol (3H2-F) and natural cortisol, when these three compounds were administered simultaneously to an adrenalectomized piglet. The relative isotope dilution of tritium was determined from the specific activities of the main urinary neutral cortisol metabolites, tetrahydrocortisone (THE) and tetrahydrocortisol (THF), normalized to that of the cortisol mixture administered. To obtain a comparison of the isotope dilution of deuterium in the metabolites THE and THF to that in the cortisol mixture, the three steroids were converted to the common oxidation product 11-oxo-aetiocholanolone, and deivatized to the methoxime-tert-butyl-dimethylsilyl ether. The relative 2H-isotope dilution then was measured by gas chromatography/mass spectrometry. It was found that the specific activity of THE in the cumulative urine collections was similar to that of the cortisol mixture administered; the two-day value was, however, less. The specific activity of THF was slightly but significantly smaller than 1 (∼0.9) at all times. The relative 2H-isotope dilution in THE was slightly but significantly larger than one (∼1.1) at all times, whereas that in the THF was larger than 1.0 at 9 and 32 h or equal to 1.0 at 20 and 47 h of urine collection. When comparing the metabolism of the two tracer cortisol species the quotient of the 3H- and the 2H-isotope dilutions in THE and THF was smaller than 1.0. It can be concluded that (2H3)cortisol may be used for the determination of the cortisol production rate.
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  • 49
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characterization of the components of a surfactant mixture is a challenge, since we are dealing with substances inherently difficult to purify or separate by any available chromatographic methods. The results of the present work provide evidence that with fast atom bombardment mass spectrometry it is possible to identify the single constituents of the different clases of tensides - non-ionic, anionic, cationic and amphoteric - directly in the mixture and in detergent formulations (shampoos). The method, which is based on unambiguous molecular weight determination of the single components, allows the definition of the exact distribution of oligomers in the surfactant mixture, and distinction of subtle variations in the detergent composition in finished formulations. The results obtained indicate that this technique is a powerful analytical tool which can be used as a rapid screen test for quality control.
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  • 50
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in vivo biliary and urinary metabolites of (±)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide (1) from male Wistar rats have been characterized by gas chromatography/mass spectrometry. In urine, non-conjugated metabolites included 1,1-diphenyl-3-butanone (4) and 3-methylamino-1,1, diphenylbutane (7). β-Glucuronidase liberated 4, 1,1-diphenyl-3-butanol (5), 1,1-diphenyl-3-butanone oxime (6), N-hydroxymethyl-N-(1-methyl-3, 3-diphenylpropyl) formamide (3), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone (11), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone oxime (12), N-methyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (8), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone (16), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanol (17), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone oxime (18), N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (14) and N-methyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (13). Most of the carbinolamide (3) decomposed in the gas chromatograph inlet to N-(1-methyl-3,3-diphenylpropyl) formamide (2) unless stabilized as a trimethylsilyl (TMS) derivative. In bile, compounds 1, 2, 3, 5, 6, 11, 12 and 16 were present as non-conjugated metabolites. β-Glucuronidase also liberated N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (9), and all of the previously listed compounds except 7. Trimethylsilylation of the conjugated bile fraction revealed the presence of an additional two compunds: N-hydroxymethyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (10) and N-hydroxymethyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (15). A stable carbinolamide metabolite standard was synthesized and the mass spectral fragmentations of its TMS derivative studied by tandem mass spectroscopy. This is the first report on stable carbinolamide metabolites of high-molecular-weight formamides.
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  • 51
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    Biological Mass Spectrometry 18 (1989), S. 713-718 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Advanced glycation products have been investigated by parent ion spectroscopy, employing B2/E = constant linked scans of furoyl ions obtained from hydrolysed glycated albumin and polylysine mixtures, without any extraction procedures. Using such an instrumental approach, together with exact mass measurements and collision spectroscopy, the identification of 2-(2-furoyl)-4-hydroxyl-1H-imidazole and 2-(2-furoyl)-4-carboxy-1H-imidazole among the advanced glycation products has been achieved.
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  • 52
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    Biological Mass Spectrometry 18 (1989), S. 719-723 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human cerumen was hydrolysed with base and the constituents were examined as trimethylsilyl (TMS), methyl ester/TMS, picolinyl/TMS and nicotinate/TMS derivatives by gas chromatography and gas chromatography/mass spectrometry. A sample was also reacted with osmium tetroxide for double bond location. The major constituents were cholesterol, squalene and several series of long-chain fatty acids and alcohols. These latter compounds had chain lengths of 12-26 carbon atoms and were predominantly either straight-chain saturated or straight-chain unsaturated compounds. Saturated branched-chain acids with methyl groups predominantly on even-numbered carbon atoms were present but were less abundant. Unsaturated, branched-chain acids were also present. The major unsaturated acids contained unsaturation at the delta-6-position or were derived from these acids by chain elongation. The compounds were similar to those found in vernix caseosa. The mass spectra of picolinyl esters were, for the first time, shown to be capable of determining both the position of unsaturation and methyl branching in the same molecule.
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  • 53
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    Biological Mass Spectrometry 18 (1989), S. 727-732 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Daughter ion mass spectral data of [M + H]+ ions of leucine enkephalin and physalaemin, which were formed by fast atom bombardment, were obtained using an instrument of EBQQ configuration. In the case of leucine enkephalin, experiments were carried out in which the collision energy was varied and the collision gas pressure kept constant and vice versa. The results show that conditions can be established under which seuqence-relevant ions above m/z 200 are formed, as well as under which mainly immonium and acylium type ions are generated. Of possible interest for characterization of unknown peptides, when using hybrid instruments, are the mid-chain cleavage ions, which, at a constant argon gas pressure of 5 × 10-6 mbat, were found to maximize at around 30 eV collision energy. Daughter ion mass spectral data are also presented for [M + H]+ ions of physalaemin (mol. wt 1264). Compared to data obtained for physalaemin on multisector instruments, our results indicate that the formation of mid-chain cleavage ions is clearly enhanced.
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  • 54
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The supernatants of Vero cell cultures after infection with a herpes simplex virus or a poliomyelitis virus as well as a blank were analysed by pyrolysis/direct chemical ionization mass spectrometry (Py/DCI MS). Informative pyrogrammes were obtained and used for characterization of viral proteins by applying pattern recognition methods. Differentiation of viral proteins was evaluated by analysing ‘blind’ samples. Herpes viruses could be classified correctly but the observed differences between the blank and the polio virus supernatants were too small for reliable classification of the polio viruses. Purification of the samples seems to be a prerequisite for further studies. The potential value of Py/DCI MS as a rapid non-invasive diagnostic method for viral meningoencephalitis is stressed.
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  • 55
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experimental variables in fast atom bombardment combined with tandem mass spectrometry based on low-energy collision-induced dissociation have been systematically invetigated in order to optimize parameters for analysis of synthetic lipo-oligopeptides. The parameters studied were matrix, ion polarity, collision gas, collision gas pressure and collision energy. The optimal parameters recommended in this study have been applied to the N-terminal amino acid seuquence determination of lipopeptide obtained from Nocardia rubra cell wall skeleton. Daughter and parent ion experiments with negative ion fast atom bombardment combined with tandem mass spectrometry have proven to be very useful for structure elucidation of a complex mixture of lipo-oligopeptides.
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  • 56
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    Biological Mass Spectrometry 18 (1989), S. 775-779 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The technique of gas chromatography/tandem mass spectrometry is applied to the analysis of bis(chloromethyl) ether in laboratory and production environments. A selected reaction monitoring method is shown to yield superior sensitivity and selectivity to previous methods. A detection limit of ∼1 ppt is established even for chemically complex atmospheres which have proved intractable by previous techniques.
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  • 57
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The negative Plasma Desorption Mass Spectra of ten unprotected tri-deoxyribonucleoside diphosphatesHereafter termed tri-deoxyribonucleotides. have been observed and analysed in detail. They all exhibit molecular ions as well as a characteristic fragmentation pattern. The ten trinucleotides selected were chosen in order to understand, in terms of sequence, the main features of the experimental spectra. It is shown that the structure and the sequence of the oligomers can be rapidly and easily derived from their PD Mass Spectrum.
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  • 58
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Positive and negative secondary ion mass spectra of the title compounds were produced by bombardment of solid deposits by 13 and 23 KeV cesium ions, respectively, and analyzed with a time-of-flight mass spectrometer. In addition to familiar protonation and alkali (mainly sodium) ion addition processes observed in the positive ion spectra and proton abstractions in the negative ion spectra (which enable determination of molecular weight) there is evidence from both spectral modes for oxidation-reduction processes in which species such as [M - H]+, [M - H + Na]+. and [M + 1]- are formed. It is argued that these may be formed rapidly from pre-associated molecules during bombardment/ionization rather than as a result of radiation damage. Sodium ion addition is apparently facilitated by the presence of electron pair donor groups, especially if chelation is possible.
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  • 59
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    Biological Mass Spectrometry 14 (1987), S. 257-261 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This study identified the reason for the poor quantification of Iormetazepam-TMS (1) using negative ion chemical ionization with lormetazepam-1,1,1-2H3-TMS (2) as an internal standard. Mass spectra of lormetazepam and its deuterium labelled compounds determined at various ion source temperatures (100-250°C) gave almost the same behaviour for 1 and lormetazepam-3′,4′,5′,6′-2H4-TMS (3) but a different one for 2, suggesting that the poor quantification was due to an isotope effect. This was confirmed by the findings that the ratios of ion currents of the base peaks of 1 and 3 were independent of the ion source temperature but those of 1 and 2 varied markedly with it. This phenomenon was also observed in the mass fragmentography of the molecular ion, although to a lesser degree than that of the above fragment. In both positive ion chemical ionization and electron impact ionization modes, no isotope effect arose because there was no corresponding fragment to cause the isotope effect.
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    Biological Mass Spectrometry 14 (1987), S. 127-129 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described to assign the positional series of methylene interrupted polyenoic acids, in complex mixtures, isolated from hydrolysed lipid extracts. It entails a simple comparison of the intensities of three ions of m/z 108, 150 and 192.
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  • 61
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behaviour of 1,1·,1″-phosphinothioylidinetrisaziridine (thiotepa) in water and aqueous salt solution of various acidity was studied by field ionization mass spectrometry (FI-MS), TLC and potentiometric titration. The rate of thiotepa hydrolysis increased with increasing thiotepa, or sodium chloride concentration, and with decreasing pH. As hydrolysis products of thiotepa, mono- and dichloro derivatives formed in neutral, salt-containing and acidic solution, tepa, and products formed by P—N bond cleavage and release of aziridine have been identified.
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  • 62
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methodology for the qualitative and quantitative analysis of the anthelmintic fenbendazole and its metabolites in goat feces using electron impact (EI)/direct exposure probe (DEP)/mass spectrometric (MS) and tandem mass spectrometric (MS/MS) techniques is presented. Analyses were conducted on extracts from spiked feces and feces from animals treated per os with 5 mg fenbendazole/kg, with samples being collected at zero time and at twelve hour intervals for 144 h. The results of the EI/DEP/MS quantitation of these samples are compared to those for the same samples analysed by high pressure liquid chromatography (HPLC). Mass spectral data for fenbendazole and its metabolites are presented and the advantages of the use of EI/DEP/MS and/or DEP/MS/MS over HPLC are discussed. This methodology may be used as a confirmatory method for the HPLC analysis of fenbendazole and its metabolites or may be used as a method in its own right for the rapid qualitative and quantitative analysis of these compounds.
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  • 63
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Known and possible phenolic and primary and secondary amine metabolites of lidocaine were added to urine from drug-naive rats. These metabolites were derivatized in this aqueous medium by acetylation with acetic anhydride or by pentafluorobenzoylation with pentafluorobenzoyl chloride. The derivatives were simultaneously extracted into an organic solvent. The products were separated by gas chromatography (flame ionization detection for acetates and electron-capture detection for pentafluorobenzoates) and identified by combined gas chromatography/mass spectrometry. Mass spectral fragmentation pathways were readily deduced; diagnostic fragment ions were identified and were valuable for characterization purposes. Structural isomers could be distinguished on the basis of their GC retention times.Extractive derivatization using pentafluorobenzoyl chloride is an attractive analytical procedure for the identification of phenolic and dealkylated metabolites of lidocaine.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 65
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    Biological Mass Spectrometry 14 (1987), S. 213-220 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermospray HPLC/MS analysis of the metabolites of arachidonic acid proved to be sensitive and specific. The compounds included were hydroxy-fatty acids (5-HETE, 12-HETE, and 15-HETE) and prostaglandins PGD2, PGE2, PGF2α, PGA2, PGA1, TXB2, and 6-Keto-PGF1α. Thermospray HPLC/MS analysis allows for simultaneous monitoring of each compound without the need for additional sample preparation or derivatization. The thermospray spectra for the metabolites exhibited [M + NH4]+ ions and fragment ions because of sequential loss of equivalents of H2O. HPLC/MS showed detection limits in the 0.5 to 5 ng range when using multiple ion detection for most of the metabolites. Post-column derivatization of these metabolites using trimethylanilinium hydroxide (TMAH) to form the methyl esters is also presented. This derivatization resulted in a gain in ion current by a factor of 3-6 for most compounds while adding potential specificity to the analysis. The thermospray spectra of the derivatives were nearly identical to the spectra of the free acid except the peaks were incremented by 14 daltons due to the methyl ester formation. The derivatization of the carboxylic acid group proved to be complete under thermospray conditions producing the maximum ion current and causing no compromise in operation of the interface.
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    Biological Mass Spectrometry 14 (1987) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Biological Mass Spectrometry 14 (1987), S. 247-248 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of polyhydrogen adducts of peptide molecules during fast atom bombardment (FAB) mass spectrometry (MS) is shown to be matrix dependent. FAB/MS analyses completed in glycerol solvent produced higher than expected peak intensities at m/z corresponding to (M + 2)+, (M + 3)+, and (M + 4)+ when the contributions of all stable isotopes present in the sample are included. Analysis of the same peptides in thioglycerol by positive or negative ion FAB yielded peak intensity distributions for the protonated molecule which matched those predicted from the natural abundance of stable isotopes. These findings suggest that thioglycerol should be the FAB matrix in analyses of peptides when determination of elemental or isotopic composition is desired.
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    Biological Mass Spectrometry 14 (1987), S. 249-256 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for calculating the empirical formulae of peptides from mass spectrometric data is described. Exact mass measurement data and isotopic peak ratios are used to generate a list of potential empirical formulae that fit a given compound within experimental error. The formulae are then analysed by a mathematical algorithm and only those corresponding to chain peptides formed from the basic amino acids are retained. Calculations conducted for typical peptides indicate that the approach may be useful for peptide identification if the experimental values are determined within an acceptable range of errors. Experimental measurements of the exact mass and isotopic peak ratios made using typical peptides demonstrate the feasibility of the approach.
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    Biological Mass Spectrometry 14 (1987), S. 303-303 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure elucidation of drug metabolites directly from urine by tandem mass spectrometry (MS/MS) for a new bronchodilator is described. When urine samples from human subjects dosed with 400 mg of MDL 257 were examined by MS/MS, three major urinary metabolites previously characterized in animal studies were confirmed and two previously unsuspected metabolites were identified.Using the operational modes of a triple stage quadrupole mass spectrometer, it is possible both to detect and to identify possible metabolites. Since the pure drug and its metabolites often contain common structural daughter ions, the parent spectra of these common daughter ions should contain some or all of the molecular ions of possible metabolites. Daughter spectra of these suspected molecular ions were obtained and the resulting daughter spectra were interpreted for structural information of suspected metabolites.This study confirms the utility of MS/MS to do rapid metabolic profiling and identification directly from complex samples such as urine, with minimal time for sample preparation and analysis. This technique can provide unique and complimentary data when combined with the more classical approaches such as HPLC profiling, isolation, and off-line spectroscopy.
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    Biological Mass Spectrometry 14 (1987), S. 339-342 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water is produced by vacuum sublimation of biological fluids directly into reaction vessels in preparation for reduction using zinc. Following heating to 450°C the hydrogen produced is admitted directly to the mass spectrometer. The standard derivation, σ10 of analysis of water samples was 1.08-1.23% while for blood plasma σ6 = 2.02-2.62%. The method allows the determination of very low levels of deuterium in biological fluids, thus allowing very small doses of deuterium oxide to be used in studies of body water in animals and possibly humans.
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    Biological Mass Spectrometry 14 (1987) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Biological Mass Spectrometry 14 (1987), S. 369-374 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A previously-unidentified peak occurring in chromatograms of the polycyclic aromatic hydrocarbon fraction from wood smoke particulate extracts analysed by capillary gas chromatography on a DB-5 column was found to correspond in retention index and molecular mass either to benzo(a)fluoranthene or to benzo(1)aceanthrylene, one of a series of four novel and highly mutagenic cyclopentafused isomers of benz(a)anthracene. Detailed sub-fractionation, and re-analysis on a liquid crystal capillary column, indicated that the identity of this peak was most likely to be benzo(a)fluoranthene, a compound not previously reported in woodsmoke.
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    Biological Mass Spectrometry 14 (1987), S. 513-516 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method was developed to measure bioavailability of lidocaine by simultaneous peroral and intravenous dosing. Lidocaine hydrochloride corresponding to 125 mg base was given perorally. Simultaneously, 30 mg of deuterated lidocaine-d3 were injected intravenously. Blood samples were taken at intervals for 270 min. Plasma samples were spiked with mepivacaine hydrochloride as internal standard, alkalinized to pH 11.7 and extracted with diethyl ether. The extracts were analysed by capillary GC ammonia CI MS using a 15 m × 0.32 mm i.d. glass capillary column coated with SE-54. The ion source pressure was 0.4 Torr of ammonia as reagent gas. Quasimolecular ions were monitored at m/z 235, 238 and 247 for lidocaine, lidocaine-d3 and mepivacaine, respectively.Calibration curves were linear from 0.2 to 5.0 nmol lidocaine ml-1 plasma. Interday reproducibility of this method was 6.9% for lidocaine-d3 (n = 16; 1.90 ± 0.13 nmol ml-1). Bioavailability of lidocaine in 5 normal volunteers ranged from 26 to 36% (mean 31 ± SD 5%) and in a cirrhotic with an end-to-side portacaval shunt it approached 100%, as anticipated. The method is well suited for determination of bioavailability of lidocaine after simultaneous administration of rather small and safe doses both intravenously and perorally.
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    Biological Mass Spectrometry 18 (1989), S. 281-286 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Positive ion fast atom bombardment mass spectra of the opioid pentapeptides leucine enkephalin (1) (H-Tyr-Gly-Gly-Phe-Leu-OH or YGGFL), methionine enkephalin (2) (H-Tyr-Gly-Gly-Phe-Met-OH or YGGFM) and leucine enkephalin-2H2 (3) (H-Tyr-2Gly-2H2-Gly-Phe-Leu-OH or YGGFL-2H2) have been recorded in glycerol. The following experiments have been carried out: (i) dimer studies [2M + 1]+; (ii) decompositions of dimers: daughter ions from (YGGFL)2, (YGGFL-YGGFL-2H2) and (YGGFL-2H2)2 as well as (YGGFM-YGGFL) and (YGGFM)2 dimers; (iii) solvation site and pyridine collision-activated dissociation studies for dimer ions; (iv) mechanism of formation of [(2M + 1) - Gly4]+ ions.
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    Biological Mass Spectrometry 18 (1989), S. 321-327 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Increasingly widespread usage of stable isotope tracers to aid clinical diagnosis and support basic research has stemmed from both advances in mass spectrometry and the availability of competitively priced labelled compounds. Stable isotopes have been used generally to investigate normal and abnormal metabolic pathways, to estimate energy expenditure and body composition and to quantitate substrate flux and oxidation rates. Despite the fact that the underlying principles relating to the use of stable isotopes for in vivo studies are straightforward, careful consideration must be given to all aspects of human studies. This review highlights some of these, including choice of label and tracer molecule, mode of tracer administration and sampling site, analytical instrumentation, interpretation of data and ethical constraints.
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    Biological Mass Spectrometry 18 (1989) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Biological Mass Spectrometry 18 (1989), S. 358-358 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The glucuronide of N-1-hydroxy-ethyl flurazepam has been analysed by a direct liquid inlet liquid chromatographic/mass spectrometric system using MeOH/H2O (70:30 v/v) as mobile phase, at a flow rate of 0.7 ml min-1. Urine samples were purified by amberlite XAD-2 chromatography; the glucuronide was quantified by highperformance liquid chromatography using a counterion (tetrabutyl ammonium nitrate in methanol). Chromatographic results were validated by an enzymatic method: treatment of the samples with β-glucuronidase and extraction of the parent drug with ethyl ether at pH 9. The biological application of this method was demonstrated by determination of this glucuronide in the urine of healthy human volunteers following a single intravenous administration of 50 mg of N-1-hydroxy-ethyl flurazepam.
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    Biological Mass Spectrometry 18 (1989), S. 373-386 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Domoic acid is a naturally occurring amino acid, formerly available in limited amounts as a natural product of some algae of the family Rhodomelaceae. As the result of a recent incidence of toxicity in cultured blue mussels (Mytilus edulis) from a highly localized region of Atlantic Canada, useful amounts of this substance are likely to become available in the near future. Domoic acid is an important substance for fundamental studies in neurobiology as it possesses the highest affinity amongst known substances for the kainate receptors of the central nervous system. The present work describes fast atom bombardment (FAB) mass spectra of domoic acid, and of some of its isomers present in minor quantities in contaminated mussel extracts. These FAB spectra are subject to interferences from beam-inducced reduction reactions associated with matrices such as glycerol, but not with others such as 3-nitrobenzyl alcohol. Tandem mass spectrometry of the MH+ ions from these compounds is also reported. As a more feasible approach to quantitative analysis at trace levels, formation of the volatile tert-butyldimethylsilyl derivatives has been investigated and shown to be highly promising.
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    Biological Mass Spectrometry 18 (1989), S. 394-400 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Collisionally activated decomposition mass spectra of M-. ions of azo dyes are presented. The compounds are of general structure Ar(1)—N=N—Ar(2), where Ar(1) is substituted phenyl and Ar(2) is 2-naphthol. Characteristic fragment ions observed include m/z 157, which corresponds to the 2-naphthol substituent with cleavage of the —N=N— bond represented as [Ar(2) - N]-.. Ion of general structure [Ar(1)- NH]- are also observed. Parent ion scans of m/z 157 provide a potential screening technique for 2-naphthol-containing axo dyes. Specific results are reported for the chloroform extract of FD&C Red #8, and capillary gas chromatographic introduction is compared with direct exposure probe introduction for the identification of dyes.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to determine the fraction of an intravenous bolus dose of ketamine which is metabolized in vivo to the corresponding N-desmethyl compound, norketamine, a novel stable isotope technique was developed and applied to a study in rats. Co-injection of equimoiar amounts of deuterium-labeled ketamine and unlabeled norketamine to four animals, followed by gas chromatographic/mass spectrometric analysis of both the administered compounds and deuterium-labeled norketamine in plasma yielded pharmacokinetic data from which the fraction of the parent drug subjected to N-demethylation (fm) was calculated from AUC data to be 36.8 ± 2.4%. It is concluded that this stable isotope co-administration technique represents a powerful approach to the determination of fm, in that the pharmacokinetics of the metabolite of interest, given as the preformed compound and generated in vivo, are determined simultaneously. This experimental design thus obviates the influence of time-dependent changes in metabolite clearance which may complicate the interpretation of studies performed using the classical cross-over design.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Chemistry and Pharmacology
    Notes: Rats given 2-octynoic acid by intraperitoneal injection excrete elevated amounts of medium-chain dicarboxylic acids and other acidic metabolites usually associated with human medium-chain acyl-CoA dehydrogenase deficiency. Onset of this organic acid profile is immediate and lasts for approximately 24 h. The induced acidosis in this animal model closely, acutely and transiently resembles the human disorder. The 2-octynoate load is also extensively Ω- and Ψ-oxidized, and evidence is presented for the enzymic hydration of 2-octynoate to 3-ketooctanoic acid.
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    Biological Mass Spectrometry 18 (1989), S. 445-449 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of dyes belonging to different chemical classes have been analyzed by thermospray (TSP) ionization mass spectrometry using a modified source containing a wire-repeller. Detection limits were determined and found to be in the range 0.05-20 ng, which are lower by a factor of 10-400 than previously published results. Positive-ion TSP mass spectra of some sulfonated dyes could be recorded for the first time owing to the increased sensitivity. Losses of SO3Na and 2SO3Na as well as losses of Na and 2Na were observed. The losses of each one of these groups involved replacement by a hydrogen atom.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct determination of 2-(2-furoyl)-4(5)-(2-furanyl)-1H-imidazole (FFI), present in the acid hydrolysis products of B-poly(L-lysine) and B-albumin and which appears to be a key intermediate in the physicochemical changes occurring during the incubation of protein with glucose, has been carried out by collisional spectroscopy, using a commercial double-focusing, reverse-geometry mass spectrometer and without any sample derivatization and chromatographic separation procedures.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the screening, quantification and confirmation of a variety of estronenic substances in animal tissues. A solid-phase extraction technique combined with a liquid/liquid extraction allows for rapid sample preparation and high throughput for the following compounds in bovine liver, muscle and kidney: diethylstilbestrol, dienestrol, hexestrol, zeranol, taleranol, zearalanone, zearalenone, zearalenol, estradiol and estriol. Gas chromatography/mass spectrometry and selected ion monitoring is used for the determination with detection limits ranging from 50 to 150 ppt.
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Combined packed column supercritical fluid chromatography/mass spectrometry has been effected using a thermospray ion source in the filament-on mode. If organic modifiers are used with carbon dioxide as the supercritical mobile phase, chemical ionization mass spectra are obtained. With carbon dioxide electron impact type mass spectra are obtained. The potential of the system is illustrated with studies of mixtures of carbamate and organochlorine pesticides and a crude ergot fermentation extract.
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    Biological Mass Spectrometry 15 (1988), S. 123-128 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new mass spectral method has been developed and used to identify biologically important thiols. This method is based upon the use of C-14 labeled N-para-bromophenylmaleimide (BPM) to selectively derivatize thiols. The isotopic label facilitates the isolation and purification of trace quantities of the maleimide thiol adducts by high performance liquid chromatography (HPLC) with radioactivity detection. The use of the bromine atom in the thiol derivative greatly enhances the detectability of the parent and fragment ions containing the BPM moiety because of the generation of the characteristic N + 2 doublet ions. Several examples of the use of this method to identify non-volatile thiol peptides such as glutathione (GSH) and homoglutathione (hGSH) by fast atom bombardment mass spectrometry (FAB-MS) are described in this report.
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  • 89
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    Biological Mass Spectrometry 15 (1988), S. 117-122 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-trans-Delta-9-tetrahydrocannabinol [(+)-delta-9-THC], a biologically inactive isomer of (-)-trans-delta-9-THC, the major psychoactive constituent of cannabis, was administered intraperitoneally to male Charles River CD-1 mice; hepatic metabolites were extracted with ethyl acetate and isolated by chromatography on Sephadex LH-20 in chloroform. The metabolites were converted into trimethylsilyl (TMS), 2H9-TMS and methyl ester/TMS derivatives for examination by gas chromatography/mass spectrometry and additional samples were prepared by reduction of metabolic fractions with lithium aluminium deuteride. Sixteen metabolites were characterized: these were alcohols and carboxylic acids, together with several of their hydroxylated analogues. The major biotransformation pathway was hydroxylation at C(11) to give the major metabolite, followed by oxidation of this compound to a carboxylic acid. Hydroxylated analogues of these two compounds were substituted mainly in the side-chain. Although metabolism was very similar to that of the naturally occurring (-)-isomer as far as positions of substitution were concerned, some differences were observed. These related mainly to the positions of hydroxylation on the side-chain, where 1′-hydroxylation was preferred to hydroxylation at the 2′-position. The major difference in metabolism between the two isomers was that much less oxidation of the 11-hydroxy group to a carboxylic acid occurred and there was less hydroxylation at the 8-position. Thus, 11-hydroxy-(+)-trans-delta-9-THC was the major metabolite and most other metabolites were hydroxylated derivatives of this compound.
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  • 90
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Negative ion chemical ionization mass spectra of prostaglandin F2α, prostaglandin E2, prostaglandin D2, 6-oxo-prostaglandin F1α, 2,3-dinor-6-oxo-prostaglandin F1α, thromboxane B2, 2,3-dinor-thromboxane B2, and 11-dehydro-thromboxane B2 pentafluorobenzyl ester (PFB)/methoxime/trimethylsilyl ether derivatives are presented. Collisionally activated decomposition mass spectra of the [M - PFB]- ions at collision energies of 8-24 eV and argon collision gas pressures of 1-2 mTorr almost show only fragmentation of trimethylsilanol, (CH3)2Si=CHOH, (CH3)2Si=CH2 and methanol whereas, except for carbon dioxide loss, only few low-intensity fragments from the carbon skeleton of the prostanoids are observed.
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  • 91
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A conventional bore liquid chromatograph has been interfaced to quadrupole and magnetic sector mass spectrometers configured for fast atom bombardment ionization via a continuous flow FAB probe. It is shown that post-column addition of FAB matrix and in-line ultraviolet detection facilities do not significantly compromise chromatographic integrity and that high quality mass spectra are obtainable from such FAB LC/MS studies.
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  • 92
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    Biological Mass Spectrometry 15 (1988), S. 193-204 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method which involves the use of tandem mass spectrometry (MS/MS) for the identification of drug metabolites has been demonstrated with a triple quadrupole mass spectrometer. The method is based on the fact that metabolites usually retain various substructures of the original drug molecule. MS/MS is capable of rapidly identifying molecules with characteristic substructures without prior separation. It is shown that this method makes it possible to postulate possible drug metabolite structures rapidly and systematically without the use of standards. The MS/MS method, as it was applied to the identification of the metabolites of a new antiepileptic drug, zonisamide, is discussed. In this case it was possible to identify isomeric metabolites due to their differences in vaporization times off the probe and their different daughter spectra. The complementary uses of the neutral loss and parent scans for the determination of the site of metabolism is demonstrated. A new figure of merit, the limit of identification, is introduced. The amount of the epoxide metabolite of carbamazepine necessary for its reliable identification in urine was shown to be 0.4 ng/μl. The application of various techniques to confirm preliminary findings with this MS/MS method are described.
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  • 93
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    Biological Mass Spectrometry 18 (1989), S. 558-562 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A specific and sensitive gas chromatographic/mass spectrometric method was developed and validated for the quantitative determination of the aromatase inhibitor CGS 16 949 in plasma and urine. A deuterium-labelled analogue of CGS 16 949 was used as internal standard. The analysis of spiked samples demonstrated the good accuracy and precision of the method. For both plasma and urine, the limit of quantification (LOQ: coefficient of variation (CV) = 10%) and the limit of detection (LOD: CV = 100%) were estimated to be 5 and 1 nmol l-1, respectively. The method was applied to the determination of unchanged CGS 16 949 in plasma and urine of a healthy volunteer orally dosed with 1 mg of CGS 16 949 A.
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  • 94
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of pipecolic acid in serum or plasma by positive chemical ionization gas chromatography/mass spectrometry is assessed. This quantitative method involves stable isotope dilution and cation-exchange solid-phase extraction. Several derivatives of pipecolic acid and its octadeuterated analogue were investigated for their mass spectrometric characteristics. The beptafluorobutyric methyl ester derivatives afford optimal resolution on gas chromatography of biological extracts. Moreover, the derivatizing reagent (methanolic HCl) allows a combined elution and derivatization. Selected ion monitoring is performed on the [M + H]+ ions of both analyte and internal standard, at m/z 340 and 348, respectively. Serum or plasma samples from healthy subjects and patients suspected of peroxisomal diseases have been examined.
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  • 95
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    Biological Mass Spectrometry 18 (1989), S. 581-591 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laser microprobe mass spectrometry has been applied to a variety of organic polyfunctional molecules, covering a wide range of polarity and mass spectrometric behaviour. The technique apparently combines desorption under relatively soft conditions with extensive fragmentation and hence allows much structural information from intactly released thermolabiles to be obtained. The mass spectra appear unfamiliar in comparison to conventional techniques. Interpretation is attempted in a purely empirical way by means of the evidence from our database and tentative hypotheses to rationalize the desorption and ionization by laser microbeam irradiation of organic solids. Selected examples are presented to illustrate the potential and limitations of the method in the field of biomolecules, such as pyridoxine and pyridoxal phosphate, nucleosides, nucleotides and related analogues, drugs and the corresponding N-oxides.
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  • 96
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    Biological Mass Spectrometry 15 (1988) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 97
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Macrocyclic trichothecenes are di- and triesters of simple trichothecenes such as verrucarol and oxygenated verrucarols. They form the negatively charged molecular (M-·) ions more effectively than the positively charged protonated molecules under chemical ionization (methane) conditions. This is proposed to be due to extended conjugation at the macrocyclic ester bridges of the molecules. The M-· ions of several macrocyclic trichothecenes undergo collisionally activated dissociation (argon) yielding the daughter ions characteristic of the ester bridges. Structures for various specific and abundant ions observed in the tandem mass spectra are proposed. The daughter ions and experimental conditions for the specific detection of these trichothecenes are selected. A semi-synthetic macrocyclic trichothecene is found to be an adequate internal standard for the analysis of macrocyclic trichothecenes under collisionally activated dissociation (CAD) conditions. Low nanogram (1-2) quantities of roridin H and satratoxins are detected under these conditions. Preliminary results indicate the applicability of this negative ion chemical ionization/tandem mass spectrometric method for the analysis of macrocyclic trichothecenes in real samples.
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  • 98
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    Biological Mass Spectrometry 15 (1988) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 99
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    Biological Mass Spectrometry 15 (1988), S. 99-104 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dehydroepiandrosterone sulphate (DHAS) has been quantified in human blood serum by fast atom bombardment (FAB)/tandem mass spectrometry of immunoadsorption extracts. FAB of DHAS yielded abundant ions corresponding to the intact steroid sulphate; these were selected by a double-focusing mass spectrometer prior to collisionally activated decomposition in a quadrupole collision cell and mass analysis by a quadrupole mass filter. [HSO4]- (m/z 97) was the sole prominent daughter ion. For quantitative analyses the quadrupole mass filter was set to transmit m/z 97 and a narrow-range magnet scan yielded a spectrum of parents, including m/z 367 and 369, corresponding to DHAS and the (2H2)-analogue (used as internal standard), respectively. Serum concentrations by this procedure were in good agreement with data obtained by gas chromatographic/mass spectrometric analyses of DHA heptafluorobutyrate, formed by direct derivatization of the steroid sulphate.
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  • 100
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    Biological Mass Spectrometry 15 (1988), S. 153-156 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron impact mass spectrometry has been used to determine the ratio of monensin A and B, and monensin A with monensin B as an internal standard in extracts of the premix and the fermentation broth. From the data obtained the total amount of monensin A and B was calculated and compared with the results of photometric determination. The relative width of the confidence intervals for the determination of monensin A and B ratio was 2% (2%) in the premix (fermentation broth), 5% (7%) for monensin A, 13% (14%) for monensin B and 5% (6%) for the total amount of monensins A and B. The limit of determination of monensins was about 100 ng. The difference in the results of photometric and mass spectrometric determination was significant for fermentation broth. No significant difference was found in the premix.
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