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  • 2020-2023
  • 1970-1974  (2,165)
  • 1965-1969  (353)
  • 1920-1924
  • Analytical Chemistry and Spectroscopy  (2,446)
  • Insulin
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  • 1
    ISSN: 1432-0428
    Keywords: Insulin ; epinephrine ; lipolysis ; glucose metabolism ; fat cell ; adipose tissue ; plasma NEFA ; KK ; yellow KK ; C57BL ; diabetes ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Adipose tissue of KK mice was less sensitive to insulin in its stimulatory action on glucose oxidation or its inhibitory action on lipolysis, and to epinephrine in its stimulatory action on lipolysis as compared to that of C57BL mice. A lack of appreciable increase in plasma NEFA in response to fasting of the KK mice might be caused by the impaired response of lipolysis to the hormones. — Adipose tissue of KK mice was also less sensitive to insulin-like action of concanavalin A, ouabaine or omission of K+ in the medium on glucose oxidation or lipolysis. Lipolysis in response to theophylline and/or DcAMP was less marked in the tissue of KK mice. The mean diameter of the adipocytes was larger in KK than in C57BL mice. In the experiments using adipocytes with the same diameter, however, the cells of KK mice were less sensitive to the hormones than those of C57BL. — With respect to tissue sensitivity to the hormones, the mean diameter of adipocytes and the response of plasma NEFA to fasting, the F1-hybrid mice of KK and C57BL showed values between those of the parental strains. Yellow hybrid (genetically obese F1-hybrid) mice showed higher sensitivity to insulin in the adipose tissue, more remarkable response of plasma NEFA to fasting as compared with KK mice, although hypertrophy of adipocytes was more pronounced in the yellow hybrid mice. — These findings suggest that insulin insensitivity is associated with epinephrine insensitivity in adipocytes of KK mice; both appear to be subjected to genetic factor(s)per se rather than hypertrophy of the adipocytes. Furthermore, insensitivity to both hormones in the KK mice appears to be caused by a common defect in cellular process other than the hormone receptor systems. These genetically determined abnormalities of adipocytes may result in fat-storage metabolism through hyperinsulinemia; this is very similar to the metabolic profile due to thrifty genotype in human diabetes as proposed by Neel.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Active Sodium Transport ; Insulin ; Aldosterone ; Vasopressin ; Ouabain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Exposure of either the isolated urinary bladder or abdominal skin ofBufo marinus to the cardiac glycoside ouabain was regularly followed by reversible decreases of electrical potential difference and short-circuit current. Residual sodium-transporting activity, stable after 1–2h, was a function of the concentration of the glycoside. 2. Ouabain-inhibited preparations still reacted to vasopressin: the hormonal effect was decreased in amplitude only, and this in proportion to decrease in baseline activity; a similar observation was made when aldosterone was responsible for hormonal stimulation. 3. On the other hand, the insulin-induced increment in sodium transport was quite sensitive to ouabain inhibition so that this hormonal effect could be eliminated at moderate concentrations of the glycoside; the same held true when sodium transport was stimulated by addition of glucose to substrate-depleted preparations, especially when they were under the influence of aldosterone. 4. The persistence of residual hormonal effects in the presence of ouabain is interpreted as a type of response due to the stimuli (vasopressin, aldosterone in the absence of exogenous substrate) influencing a step distinct from, and probably proximal to, the ouabain-sensitive sodium “pump” mechanism proper. As for the increased ouabain effect noted on preparations stimulated by insulin or by glucose repletion, it suggests another type of response, possibly characterized by a facilitated interaction between ouabain and specific cell membrane ATP-ase set in operation as a consequence of these treatments.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 348 (1974), S. 333-342 
    ISSN: 1432-2013
    Keywords: Mouse Pancreas ; Amylase ; Glucose ; Insulin ; Glucagon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Glucose inhibited amylase release from batch-incubated and perifused pieces of mouse pancreas. Insulin (100μg/ml) reduced the amylase secretion. These effects, however, seemed to be independent of each other, since diazoxide, a potent inhibitor of glucose-induced insulin release, did not abolish the effect of glucose on amylase secretion. Glucagon (10–100 μg/ml) had no effect on the release of amylase from incubated pancreas. Glucagon has previously been shown to inhibit exocrine secretionin vivo. The present results suggest that the inhibitory action of glucagon may be mediated via an increased level of serum glucose and the subsequent release of insulin.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 117 (1974), S. 63-72 
    ISSN: 1432-1076
    Keywords: Growth hormone ; Newborn ; Glucose load ; Insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intravenous glucose tests (0.5 g/kg body weight) were performed in 13 newborn infants during their first 3 days of life. The variations in blood glucose, insulin and GH values were studied. In all patients there was a rise in plasma insulin. The correlation between initial insulin rise and glucose assimilation constant was 0.503 which is almost significant. The glucose load provoked a very variable response in plasma GH concentration, some infants showed a rise, others a fall. If the newborns were grouped according to this reaction it appeared that the GH response could be explained using Wilder's law of initial value. This hypothesis, however, did not stand up to a thorough statistical analysis including a discussion of a less well-known statistical error. In contrast to insulin secretion, GH apparently plays no major role in the short term regulation of the blood sugar in the newborn.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 33 (1974), S. 215-226 
    ISSN: 1439-6327
    Keywords: Exercise ; Training ; FFA ; Ketones ; Insulin ; Growth Hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eight young men underwent a programme of training by running for 30 min at moderate speed three times a week for 4 weeks. Metabolic and hormonal changes in blood were studied during and after a run of 60 min at comparable speeds before and at the end of the training programme. Increases in lactate, pyruvate and plasma FFA during exercise were less after training. Increases in glucose were greater. There was a smaller increase in the post-exercise concentration of blood ketone-bodies after training. Plasma levels of insulin and human growth hormone (HGH) were lower after training. The fall in insulin and the rise in HGH during exercise were also smaller. There is a dissociation of the normal relationship between blood glucose and insulin during exercise. Insulin appears to be more important in the control of fat metabolism, in which its role may be altered by physical training. The changes observed in the longitudinal study of training imply that differences observed in cross-sectional studies of athletes and untrained subjects are not the result of an innate difference but do depend upon metabolic changes related to athletic training.
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  • 6
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Repetitive mass spectrometric scanning of gas-liquid chromatographic effuents at short (6 to 15 s) intervals, with a digital computer for data acquisition, reduction and display, allows plots (mass chromatograms) to be made of the intensities of specific ion fragments. Plotting of m/e values characteristic for certain classes of compounds and/or individual components reveals the location of constituents in the gas chromatogram. This technique was applied to the identification of trimethylsilyl derivatives of unsubstituted and 2-hydroxy fatty acid methyl esters in mixtures obtained from acid catalyzed methanolysis of cat brain galactocerebrosides. The plot of total ionization intensity vs scan number generated the gas-liquid chromatogram. Mass chromatograms of m/e 73 and [M - 59]+ gave the locations in the gas-liquid chromatogram of the hydroxy fatty acid derivatives, and mass chromatograms of m/e 74 and [M]+ located the unsubstituted fatty acid derivatives. Integrated ion intensities were used to determine the composition of the mixture of fatty acids.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 20-28 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complete mass spectra of the pertimethylsilylated derivatives of three high molecular weight polyene macrolide antibiotics are reported for the first time. The fragmentation pathways which are proposed have been corroborated by the stable isotope derivatives d9-TMS and d3-acetyl. Accurate mass measurements and metastable transitions confirm the proposed fragmentation mechanisms in the low mass range. Nystatin - the macrolide of highest molecular weight in this study - expels several TMSOH molecules and a TMS radical. Amphotericin B underwent extensive rearrangements preliminary to eliminating a series of TMSOH molecules. An apparent equilibrium between the keto and ketal forms of amphotericin B facilitated the rearrangements. Pimaricin fragmented in a manner parallel to that of the other two macrolides. The sugar portion of the molecules dominated the fragmentation in the low mass region in the spectra of all compounds. The transfer of a TMS group from the sugar amine to the glycosidic oxygen was observed when the amino sugar was eliminated from the intact molecule. The resulting sugar ion then expelled ammonia.
    Additional Material: 5 Ill.
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  • 8
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the separation, identification and quantitation of endogenous hydrogenated metabolities of corticosterone in rat liver Corticosterone, 5α- and 5β-dihydrocorticosterone, 3α,11β,21-trihydroxy-5α-pregnane-3,20-dione, 3β,11β,21-trihydroxy-5α-pregnane-3,20-dione, 3α,11β,21-trihydroxy-5β-pregnane-3,20-dione, 3β,11β,21-trihydroxy-5α-pregnane-3,20-dione, 5α-pregnane-3α,11β,20α,21-tetrol, 5α-pregnane-3α,11β,20β,21-tetrol and 5α-pregnane-3β,11β,20β,21-tetrol are specifically quantitated in one analysis by mass fragmentography all as their O-methyloxime pertrimethylsilyl derivatives. A pronounced difference in the amounts of these nine metabolites between male and female adult rats was found, while in newborn rats only the two tetrahydro-compounds bearing a 5α-hydrogen were detected in both sexes. On the other hand 3α,11β,1 5α,21-tetrahydroxy-5α-pregnan-20-one was detected only in the adult female as its second prominent metabolite of corticosterone. Corticosterone metabolites being biochemical markers of the sex-linked differentiation of the hepatocytes, their mass fragmentographic assay is proposed as a tool for the quantitative analysis of this type of gene expression.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 62-65 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separation and structural determination of ten partially methylated methyl glucosides by gas chromatography and gas chromatography-mass spectrometry are described. These glucosides were four possible structures for methyl tri-O-methylglucosides and six for methyl di-O-methylglucosides. The positions of free hydroxyl groups in four isomers of methyl tri-O-methylglucosides could be fairly distinguished from each other by their mass spectra. Mass spectra of methyl di-O-methylglucosides were similar to each other, though their spectra were different from those of fully methylated or methyl tri-O-methylglucosides. After introduction of a trimethylsilyl group to the free hydroxyl group, mass spectra of methyl di-O-methylglucosides showed a characteristic pattern for the position of the trimethylsilylated hydroxyl group, and O-trimethylsilyl ethers of methyl tri-O-methylglucosides also showed distinguishable mass spectra. The structures of fragment ions of partially methylated methyl glucosides were confirmed by high resolution mass spectrometry.
    Additional Material: 4 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 80-82 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monitoring of solutes eluted from a liquid chromatograph is possible by continuous introduction of the effluent solution into the ion source of a chemical ionization mass spectrometer. Detection sensitivities in the nanogram range are possible for a wide variety of solutes and solvents. Auxiliary techniques which have proved valuable for g.c.-m.s. also appear to be applicable to l.c.m.s.
    Additional Material: 3 Ill.
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  • 11
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of drug metabolites is very important in the biochemical field. However, the procedure for doing this has been very complicated in many cases. The major reason is because of the need for fairly large amounts of the samples. We have been studying procedures for the determination and identification by use of mass spectrometry, which usually gives a lot of information rapidly from very small amounts of the samples (below μg). In this paper, the metabolites excreted in urine and bile following oral administration of 2-(diethyamino)ethyl tetrahydro-α-(1-naphthylmethyl)-2-furanpropionate oxalate (1) in rats, were investigated by means of mass spectrometry and other techniques. The drug was not excreted unchanged in urine. Of the eight metabolites suspected to be present in urine and bile, the structures of three metabolites were elucidated to be tetrahydro-α-(1-naphthylmethyl)-2-furanpropionic acid (3) and α-(1-naphthylmethyl)-2-perhydro-5-oxofuranpropionic acid (4) in urine, and diethylaminoethanol (2) in bile. These metabolites might also be present as their structural isomers or conjugates.
    Additional Material: 11 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. xiv 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 83-95 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of the integrated ion current technique for the analysis of biogenic amines and phenols as their 1-dimethylaminonaphthalene-5-sulphonyl (dansyl) derivatives is described, particularly as regards to the linearity and sensitivity of detection. The mono derivatized amines gave a linear response over the range 10-9 to 10-14 mol, with a few being detected in quantities as small as 5 × 10-15 mol. The bisdansyl derivatives have a lower sensitivity and the response is linear over a more restricted range, terminating at 10-13 mol. Deuterated analogues of some of the amines were prepared and the feasibility of their use as internal standards was investigated. In this way, the problems associated with quantitative biochemical analyses caused by losses during extractions, chromatographic separations and thermal decomposition in the mass spectrometer lon source are overcome. The differentiation of isomers of biogenic amines as their dansyl derivatives has been accomplished by fractional sublimation and by examination of differences in their fragmentation patterns.
    Additional Material: 7 Ill.
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  • 15
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 115-119 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amino acids, arginine, citrulline, cysteine, cystine, histidine, hydroxyproline, methionine, ornithine, proline, serine, threonine, tryptophan and tyrosine, have been analysed in the form of their N-(N′, N′-dimethylaminomethylene) methyl esters. formed in a single step by reaction of the free amino acid or its hydrochloride with N,N-dimethylformamide dimethylacetal in acetonitrile/methanol (2:1). A reaction time of 15 minutes at 100 °C ensures complete derivatization, the derivatives being volatile at source temperatures below 150 °C, and giving electron impact spectra characterized by abundant (or moderately abundant) peaks at or near the mass of the molecular ion.The analysis of amino acid mixtures by mass fragmentography on characteristic high mass peaks of their N-(N′,N′-dimethylaminoethylene) methyl ester derivatives, introduced on a direct insertion probe and volatilized during temperature programming of the source, is qescribed. The method is applied to the analysis of a mixture containing arginine, citrulline, cystine, histidine and tryptophan, traditionally difficult to analyse by other methods.
    Additional Material: 6 Ill.
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  • 16
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of cyclophosphamide-4-d2 (2-[bis(2-chloroethyl)amino]-tetrahydro-4,4-dideuterio-2H-1,3,2-oxazaphosphorine 2-oxide), was studied. The first detectable metabolite was a hydroxy derivative which was trapped with ethanol. Mass spectrometry of the resulting two ethoxy derivatives and of the deuterated acrolein 2,4-dinitrophenylhydrazones formed therefrom via reaction with acidic 2,4-dinitrophenylhydrazine, afforded evidence that the ethoxy substituents were at C-4, which was therefore the position of the original hydroxy substituent. The mass spectrum of the deuterated acrolein 2,4-dinitrophenylhydrazone obtained from the total reactive metabolites was used to estimate the ratio of 4- to 6-hydroxylation. The rate of metabolism and the antitumour activity of cyclophosphamide and its 4-d2 analogue were compared.
    Additional Material: 3 Ill.
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  • 17
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The organic material in airborne particulate matter is being studied by high resolution mass spectrometry to determine if hydrocarbons typical of major sources of pollution can be detected. Carbon number distributions and hydrogen-to-carbon ratios of components found in airborne particulate samples and the corresponding data for compounds detected in fuel combustion products show great similarity. Samples collected near large power stations and major airports were compared with typical urban particulate samples. Particulates collected from jet engine exhaust and a condensate from the stack effluent from a coal-fired combustion system were studied. Mass spectral data were obtained for an auto exhaust tar, a coal tar pitch and several fuels. The mass spectra of two total particulate samples, compared to the spectrum of an ether extract of the organic matter, indicate that direct vaporization can be used and extraction is not essential for qualitative mass spectral studies.
    Additional Material: 7 Ill.
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  • 18
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 154-155 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first application of field desorption mass spectrometry to the analysis of intact diacyl glycerophosphorylcholines (lecithins) has led to the detection of prominent molecular ions. This technique enables positive identification of the components of a mixture of phosphatidylcholines, which will provide valuable information on the phospholipid composition of biological fluids.
    Additional Material: 1 Tab.
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  • 19
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 157-157 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 20
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. xi 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 21
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 159-162 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high resolution mass spectrometric integrated ion current procedure has been used to identify and quantitate amphetamine, isolated as its dansyl derivative, as it is found after addition to urine and in tissues of the rat following intraperitoneal injection. A linear relationship between amphetamine and ion current response has been established at least in the range 5 × 10-12 to 5 × 10-7 g, and as little as 8 × 10-13 mol of amphetamine in urine may be detected.
    Additional Material: 3 Ill.
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  • 22
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 166-168 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is described for the identification of the sapogenins of several Digitalis species. The steroids are separated by repeated development thin-layer chromatography and identified by means of high resolution mass spectrometry. The spectra of tigogenin, gitogenin, digalogenin and digitogenin are recorded. These spectra are of particular use in establishing the position of extra hydroxy moieties in the steroid nuclei. Several species of Digitalis were screened for their sapogenin content. D. purpurea, D. mertonensis and D. lutea were found to contain tigogenin and digitogenin in small amounts, the principal steroid being gitogenin, whilst D. ambigua and D. lanata contained all four steroids.
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  • 23
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 172-174 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetic acid isolated from cider vinegar and inorganically synthesized glacial acetic acid have markedly different intramolecular isotopic distributions of the stable carbon isotopes. Carbon-12 is concentrated in the methyl group relative to the carboxyl group in the biologically produced acid. The reverse distribution is observed in the particular sample of glacial acetic acid examined here.
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  • 24
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 192-194 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analysis has been made of a sample of rain water collected in Washington, D.C. following a sustained photo-oxidant smog alert which was accompanied by haze and low visibility. The analysis was effected by purging the organic content from the water with helium gas and identifying the constituents by means of gas chromatography - mass spectrometry. The predominant compound was found to be 3-methylfuran, a possible intermediate or end product of the atmospheric decomposition of terpenoid hydrocarbons. The analysis suggests that the smog resulted from the air oxidation of hydrocarbons evolved from Appalachian forestation rather than from manassociated activities.
    Additional Material: 3 Ill.
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  • 25
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Combined gas chromatography-mass spectrometry and isotope labeling techniques have been employed to demonstrate that the carboxamide nitrogen atom in 2-carboxamido-5-isopropoxycarbonylaminobenzimidazole, a metabolite of 2-thiazolyl-5-isopropoxycarbonylaminobenzimidazole (cambendazole), is derived wholly from the parent drug. [15N] Thiazole-labeled cambendazole was administered to a rat and the metabolite isolated from urine. Trideutero-2-carboxamido-5-isopropoxycarbonylaminobenzimidazole was employed as a carrier to isolate the metabolite in sufficient purity for isotope ratio measurements using multiple ion detection. The metabolite was converted to its tetramethyl derivative by on-column reaction with trimethylanilium hydroxide to permit satisfactory gas chromatography.
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  • 26
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 206-207 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 27
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. xiii 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 28
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 29
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    Biological Mass Spectrometry 1 (1974), S. 219-222 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twelve derivatives of bilirubin were evaluated from the point of view of providing intense molecular ion peaks on electron impact and unambiguous molecular weights. The tetrakis-(trimethylsilyl) derivative of bilirubin was judged to be the most suitable because its molecular ion carries 22% of the total ion current and is the base peak in the spectrum. Molecular ions were found to carry 10% of the total ion current in the spectrum of the trimethylsilylated methyl ester of the phenylazo derivative of bilirubin. Fragmentation patterns of these two compounds were studied using deuterium labeling.
    Additional Material: 3 Ill.
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  • 30
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectrometric analysis of peptide mixtures may lead to ambiguous results when it is possible to change from one peptide chain to another during the interpretation of the spectra. This kind of ambiguity can be eliminated by submission of part of the sample to one cycle of Edman degradation, followed by comparison of the results obtained for this preparation with those obtained for the nondegraded sample. Combination of this procedure with the use of deuterated derivatives has allowed an unambiguous interpretation for two mixtures of synthetic peptides.
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  • 31
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    Biological Mass Spectrometry 1 (1974), S. 256-262 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The field desorption mass spectra of ten medicinal carbamates - meprobamate, mebutamate, carisoprodol, emylcamate, bethanechol chloride, styramate, hydroxyphenamate, mephenesin carbamate, methocarbamol and chlorphenesin carbamate - were run and compared with their published electron impact spectra. Of the ten compounds run only emylcamate did not give a field desorption mass spectrum. All others gave abundant molecular ions, with the exception of bethanechol chloride which has a quarternary ammonium group and gave a field desorption spectrum characteristic of compounds possessing such a functional group. No general characteristic fragmentation was attributed to the carbamate function in the field desorption mode. However, the ease of obtaining abundant molecular ions or quasimolecular ions makes the field desorption method a valuable complementary technique to electron impact studies of carbamates.
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  • 32
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    Biological Mass Spectrometry 1 (1974), S. 269-273 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An azurin, a small respiratory copper protein from the bacterium Pseudomonas fluorescens biotype G, has been studied by mass spectrometry to determine sequence information. The study of homologously related proteins by mass spectiometry is particularly attractive, since the correct nature of major parts of the deduced sequences can be confirmed by comparison with the sequences of the protein from related organisms. An oxidized tryptohan residue has been identified amongst the products from a cyanogen bromide digest of this wild type azurin. In the same digest, a product is also found to arise from cleavage of the peptide chain at the C-terminal side of the same tryptophan residue. These results are rationalized.
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  • 33
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral data for the primary fragmentation of partially ethylated alditol acetates have been tabulated in order to allow easy reference for the identification of these polysaccharide derivatives. Sodium borodeuteride is used in all the aldose to alditol reductions, since the presence of a single deuterium label on C-1 greatly increases the information available in the mass spectrum and allows some identifications to be made which would not otherwise be possible. The primary fragmentations of these derivatives are analogous to those of the partially methylated alditol acetates, with each fragment shifted to a higher m/e value by fourteen mass units for each ether linkage contained in the fragment. The secondary fragmentation is also very similar, being characterized by the loss of acetic acid or ketene, or, less frequently, by the loss of ethanol or acetaldehyde. Coupled with the chromatographic retention time data for the partially ethylated alditol acetates tabulated elsewhere, the unambiguous mass spectral identification makes this derivative an excellent choice as a complementary derivative to the partially methylated alditol acetates for polysaccharide analysis. The utility of the partially ethylated alditol as a routine analytical derivative is further enhanced by the almost identical procedures required for synthesis of the ethyl and methyl derivatives. Through the combined use of these derivatives, most of the possible linkage isomers of the seven common aldoses of plant cell wall polysaccharides can be resolved, identified and quantitated.
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  • 34
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    Biological Mass Spectrometry 1 (1974), S. 281-285 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of most nucleosides of cytosine exhibit molecular ions of low abundance, rearranged ions base + 2H in greater abundance than the companion species base + H, and a characteristic and abundant ion which corresponds to base + C2HO from the sugar. Deuterium, oxygen-18 and substituent labeling showed the presence of C-1′, 2′, H-2′ and O-4′ in the latter ion, which led to a proposed mechanism of formation involving opening of the sugar ring and recyclization between O2 and C-2′ with expulsion of water. Primary driving force for the reaction is due to resonance stabilization promoted by unshared electrons from N4, which results in diminished abundance in the case of imino isomers and derivatives which contain electron-withdrawing groups at N4, and enhanced abundance resulting from methylation at N4. Data for 24 nucleosides are presented and discussed in terms of the determination of nucleoside structure.
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  • 35
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    Biological Mass Spectrometry 1 (1974), S. ix 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 36
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of sodium dipropylacetate (a newly developed anticonvulsant) was investigated in rats, and two metabolites were found in urine of rats which received dipropylacetate. The metabolites were identified as 2-n-propyl-5-hydroxypentanoic acid and 2-n-propylglutaric acid, respectively, by low and high resolution mass spectrometry. Synthetic 2-n-propylglutaric acid, when administered to rats, was not oxidized further and was excreted intact in urine. These data clearly show that ω-oxidation is involved in the metabolism of sodium dipropylacetate and that 2-n-propylglutaric acid, the end product of ω-oxidation, does not serve as a substrate for β-oxidation.
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  • 37
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The precise isotopic analysis of carbon by means of differential comparison of CO2 samples is applied to neutral, acid c and basic extract fractions of human urine. It is shown that the standard deviation of the analytical procedure, including sample preparation steps, is about 1% or 0.001 atom % excess carbon-13, but depends some what on the fraction considered. Day to day variations (expressed as standard deviations) in the isotopic composition of the urine fractions are generally less than 2.8%, 1.4% and 3.9% for the neutral, acidica and basic fractions, respectively, although the effect of unusual dietary inputs can be recognized. The ingestion of 23 μg excess carbon-13 in the form of isotopically labelled aspirin is shown to perturb significantly the isotopic composition of the acidic urine fraction which, for a 24 hour collection period, had a mass of 570 mg C. Because only 0.01% of the fraction was consumed by isotopic analysis, further extensive analysis would be possible. It is concluded that carbon-13 tracer experiments generally should be arranged to provide at least 5 × 10-5 g excess 13C/g carbon in any fraction which is to be used for lable detection.
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  • 38
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    Biological Mass Spectrometry 1 (1974), S. 363-364 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of a mixture twenty dansyl derivatives of biogenic amines were run using low energy electron impact. This method appears to be useful for the analysis of amines present in biological materials.
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  • 39
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    Biological Mass Spectrometry 1 (1974) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 40
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    Biological Mass Spectrometry 1 (1974), S. 374-380 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the trimethylsilyl derivatives of thyroxine and sixteen related compounds are reported. In addition to deiodinated analogues and iodinated tyrosines, the latter include a series of thyroacetic and thyropropionic acids and one thyroformic acid compound. Their spectra are discussed in terms of their fragmentation and utility for qualitative and quantitative estimation by gas chromatography - mass spectrometry.
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  • 41
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    Biological Mass Spectrometry 1 (1974), S. 386-392 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of synthetic methoxychlorobiphenyls have been investigated. These substances are of interest as reference compounds in studies of the metabolism of chlorobiphenyls. Some characteristic fragmentation patterns have been found, useful for differentiation between the 2-, 3- and 4-methoxychlorobiphenyl isomers. Thus, mass spectra of 2-methoxychlorobiphenyls show large fragments at [M - CH3Cl]+., while those of 4-methoxy compounds differ from 3-methoxy isomers by the presence of significant [M - CH3]+ fragments in the former.
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  • 42
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical ionization mass spectra of four explosive compounds have been obtained by using water as reagent gas. The compounds are 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane, 1,3,5-trinitor-1,3,5-triazacyclohexane, pentaerythritol tetranitrate, and an explosive which has been used in letter bombs, containing the two latter compounds and a plasticizer. The chemical ionization H2O mass spectra were recorded at an ion source temperature range of 170 to 225°C, a probe temperature range of 160 to 265°C and a reagent gas (H2O) pressure range of 0.07 to 0.10 Torr. Unlike in chemical ionization using methane or isobutane, chemical ionization H2O spectrum of these compounds provides a method for obtaining quasimolecular peaks. Adduct ion peaks like [M + H3O]+, [M + H5O2]+, [M + NO]+ and [M + NO2]+ are also observed in the chemical ionization H2O mass spectra of these compounds. Chemical ionization H2O mass spectra provide thus a better means of explosive identification.
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  • 43
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    Biological Mass Spectrometry 1 (1974), S. 412-414 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetobacter suboxydans, strain 8.3, was grown using ethanol, made by the hydration of ethylene, as the sole energy source. After the microorganism had oxidized some of the ethanol to acetic acid, the unassimilated alcohol and produced acetic acid were isolated from the supernatant. Carbon isotopic analyses of these compounds and the starting ethanol show: (1) the methyl carbon of the starting alcohol is enriched in carbon-13 by 4.6% relative to the hydroxyl carbon, (2) the starting alcohol contains 2% less carbon-13 than the unassimilated ethanol and (3) the carboxyl carbon of the acetic acid excreted by the A. suboxydans is enriched by 3.8% in carbon-13 relative to the methyl carbon. These results support earlier findings which indicate that organisms preferentially utilize compounds enriched in carbon-12 and tend to concentrate carbon-12 in the reduced carbons relative to the oxidized carbons of metabolic products.
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  • 44
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    Biological Mass Spectrometry 1 (1974), S. 423-424 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact, chemical ionization and field desorption mass spectra of seven steroids showing varying stability to electron impact have been compared.
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  • 45
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    Biological Mass Spectrometry 1 (1974), S. 427-428 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 46
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    Biological Mass Spectrometry 1 (1974), S. ix 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 47
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 48
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    Biological Mass Spectrometry 1 (1974) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
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    Biological Mass Spectrometry 1 (1974), S. xi 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 50
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 3′- and 5′-O-t-butyldimethylsilyl derivatives of thymidine and deoxyadenosine have characteristically different mass spectra and can be separated by gas chromatography.
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  • 51
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The difficulty of collecting volatile hydrocarbons, such as benzene, from street air in a form suitable for subsequent analysis is overcome by the use of a time-based elution procedure. By linking this technique to a gas chromatograph-mass spectrometer-data system, a rapid analysis is possible for low concentrations of collected material. Among advantages of this novel sample introduction procedure are the facility for collecting organic materials without interference from water vapour and their subsequent introduction into the g.c.-m.s. system without the use of any auxiliary solvents. Consequently the mass spectrometer can be used continuously on-line enabling the more volatile materials, normally masked by solvents, to be examined. This procedure is illustrated by the measurement of benzene and other hydrocarbon levels in street air (London). Following gas chromatographic separation the hydrocarbons can be identified by library search facilities attached to the mass spectrometer.
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  • 52
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    Biological Mass Spectrometry 1 (1974), S. xiv 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 53
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    Biological Mass Spectrometry 1 (1974), S. xv 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 54
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    Biological Mass Spectrometry 1 (1974), S. 96-102 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several reagent gases and mixed reagent gases for high pressure ion-molecule reaction ionization of samples have been investigated for use in gas chromatography-mass spectrometry analyses. The common g.c. carrier gases and their mixtures with other gases such as isobutane, ammonia, tetramethylsilane, hexafluoroacetone and nitric oxide, were studied. These reagents were used to enhance the molecular ion intensity and to simplify the spectra of steroidal alcohols and the trimethylsilyl ethers of biologically important compounds.
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  • 55
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The presence of epinine in adrenal medulla and in reaction mixtures of enzymic in vitro experiments is proven by mass fragmentography. Derivatization of catecholamines, suitable for gas chromatographic analysis is discussed. The perfluoropropionates were selected for mass fragmentography.
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  • 56
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using methylsulphinyl carbanion as base. methylation of 17-ketosteroids with methyl iodide not only converts hydroxy into methoxy groups, but also replaces both C-16 hydrogen atoms by methyl groups. These permethyl derivatives are very stable, have excellent properties for gas chromatographic separation and fragment characteristically upor electron impact. The mass spectra of a number of these derivatives are discussed.
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  • 57
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    Biological Mass Spectrometry 1 (1974), S. 120-123 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high resolution field desorption mass spectra of a number of glycosides are described. In all cases the spectra enabled molecular weights and elemental formulae to be established, and the presence of fragment ions due to cleavage of the sugar groups provides considerable assistance in the identification of sugar and aglycone moieties. The [M + 23Na]+ ion was the base peak in the spectrum of the sodium salt of testosterone glucuronide, and the presence [M + 39K]+, [M + 41K]+ and [M + 23Na]+ ions in the spectra of other glycosides are attributed to the presence of their sodium or potassium salts as impurities.
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  • 58
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary results are reported for the quantitative determination of the antiarrhythmic agents quinidine and lidocaine in human plasma by combined isobutane chemical ionization mass spectrometry and stable isotope labeling. The concentration of monoethylglycinexylidide, a known metabolite of lidocaine, was also determined using this method. In the procedure used, stable isotope analogs of the materials to be determined were added to serial plasma samples. The plasma was then made basic and extracted with benzene. The residue after evaporation of the solvent was placed directly into the mass spectrometer via the direct insertion probe and the spectrum determined. In this manner the above named compounds could readily be quantitated without recourse to either derivitization or further purification.
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  • 59
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    Biological Mass Spectrometry 1 (1974), S. 142-144 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The urinary excretion of butobarbitone and its metabolites has been studied quantitatively using combined gas chromatography-mass fragmentography, tuned to ions at m/e 169 and 184. After a single oral dose (200 mg) to healthy male volunteers, unchanged drug (7 to 9%), 3′-hydroxybutobarbitone (22 to 27%), 3′-oxobutobarbitone (14 to 18%) and the 3′-carboxylic acid (4 to 8%), were found. In all cases, the maximum rate of excretion was in or near the third 12 hour urine.
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  • 60
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    Biological Mass Spectrometry 1 (1974), S. 156-157 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 61
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high resolution, electron impact mass spectrum of 1,6-anhydro-3,4-O-isopropylidene-β-D-talopyranose, together with those of its derivatives having specific deuterium substitution at C-2, at C-3, at C-2 and C-3, and in the isopropylidene group, is considered in detail and compared with the ammonia and isobutane mediated chemical ionization spectra of these five compounds. From the elemental compositions of the fragment ions and mass number shifts upon deuterium incorporation, the origin of the hydrogen atoms in each of the fragments is traced, and a detailed scheme of the main fragmentation. pathways is presented.
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  • 62
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    Biological Mass Spectrometry 1 (1974) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 63
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    Biological Mass Spectrometry 1 (1974), S. 163-165 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methyl derivative of tolbutamide, obtained by the action of dimethyl sulfate, has been subjected to g.c.-m.s. at high resolution. From the mass spectrum it is deduced that methylation of the sulfonamide nitrogen atom has occurred. During the loss of SO2 from the molecular ion, aryl rearrangement to both oxygen and nitrogen occurs in the ratio of 1:2.
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  • 64
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    Biological Mass Spectrometry 1 (1974), S. 169-171 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Characterization of the B vitamins. pyridoxal, pyridoxamine, their phosphates and thiamine salts by electron impact mass spectrometry is difficult. A new technique, field desorption, is applied in ionizing these molecules for mass spectrometric analysis Characterization of these compounds by field desorption has the advantage that in each case the most intense peak in the spectrum is formed without fragmentation.
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  • 65
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectra of a series of stable isotope derivatives aided a structure elucidation study of an amino acid amide (Tyr-NH2) and the following family of synthetic oligopeptides: Gly-Tyr-NH2, Gly-Gly-Tyr-NH2, Gln-Gly-Gly-Tyr-NH2, Gln-Gln-Gly-Gly-Tyr-NH2, Ala-Gln-Gln-Gly-Gly-Tyr-NH2, Ser-Ala-Gln-Gln-Gly-Gly-Tyr-NH2 and Lys-Ser-Ala-Gln-Gln-Gly-Gly-Tyr-NH2. This series of peptides was synthesized by classical methods. N,O-permethylated, N-acetylated derivatives were synthesized to provide sufficient volatility for mass spectrometry. Various combinations of stable isotope derivatives (CH3CO + CH3, CD3CO + CH3, CH3CO + CD3, CD3CO + CD3) confirmed proposed fragmentation pathways and corroborated hypothetical ion structures. This family of oligopeptides corresponds to the C-terminus of scotophobin.
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  • 66
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    Biological Mass Spectrometry 1 (1974), S. 195-198 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatography-mass spectrometry has been used to identify the phosphate diester backbones of two classes of phospholipids previously unrecognized in washings from human lungs. Washings were analyzed from two patients with pulmonary alveolar proteinosis and also from two pairs of normal lungs washed postmortem. α-Glycerophosphorylglycerol and α-glycerophosphorylinositol were identified in all four cases following hydrolysis of the fatty acid esters and treatment with trimethylsilylating reagent.
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  • 67
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    Biological Mass Spectrometry 1 (1974), S. 207-208 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 68
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the methyl-, ethyl- and benzyl-oxime trimethylsilyl ester derivatives of sixteen oxocarboxylic acids are reported. They are discussed both in terms of their fragmentation and their utility for use in studies of inborn errors of metabolism. Several applications where these derivatives have proved of value are presented.
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  • 69
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    Biological Mass Spectrometry 1 (1974), S. 209-211 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thirty-two organic contaminants have been identified in District of Columbia drinking water. These contaminants include aliphatic and aromatic hydrocarbons, chlorocarbons, bromine-containing compounds, alcohols and ketones. The concentration of each constituent identified was less than one part per million. The organic contaminants were extracted from the water samples with a 1:1 mixture of carbon disulfide (CS2) and methylene chloride (CH2Cl2). Each constituent was identified by its gas chromatographic retention time and by its mass spectrum.
    Additional Material: 1 Tab.
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  • 70
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    Biological Mass Spectrometry 1 (1974), S. 212-218 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The components of mixtures of dipeptides can be identified from the electron ionization and chemical ionization mass spectra of their N-acetylacetonyl methyl ester derivatives without prior separation. The pyrolytic conversion of peptide trimethylanilinium salts to their methyl esters in the direct insertion probe of a mass spectrometer was found to be most suitable for the derivatization of dipeptides in mixtures.
    Additional Material: 4 Ill.
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  • 71
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    Biological Mass Spectrometry 1 (1974), S. 223-230 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some of the known and important metabolites of cyclophosphamide and the parent drug itself were investigated by low and high resolution field desorption mass spectrometry. The potential of the relatively new analytical method for the determination of the molecular weight and elemental formulae of drugs and drug metabolites was exemplified. This holds for pure, synthetic compounds as well as for contaminated extracts from biological sources. In addition, by thermally-/field-induced fragmentation, diagnostic fragment ions could be produced, providing valuable structural information. Further, an indication on how to distinguish [M]+. and [M + H]+ ions in field desorption mass spectrometry is given. The ability to identify these ions unambiguously is critical for interpretation. Finally, the potential of the method as applied to drug and drug metabolite mixtures is evaluated. The results indicate that field desorption mass spectrometry is a promising tool in metabolism studies.
    Additional Material: 6 Ill.
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  • 72
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    Biological Mass Spectrometry 1 (1974), S. 252-255 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High resolution mass spectrometry has been used to identify phenylbutanone in plasma extracts. Concentrations of 5 μg/ml of the drug in plasma have been determined by a gas chromatographic method with a standard deviation of ±0.3%.
    Additional Material: 3 Ill.
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  • 73
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amino acid sequences of the thirteen tryptic peptides of the cowpea strain of tobacco mosaic virus (Cowpea TMV) protein were determined by a combination of the mass spectrometric and Edman degradation procedures. In order to complete the amino acid sequences, a number of the tryptic peptides were further digested with chymotrypsin, thermolysin and carboxypeptidases A and B. The peptide fragments were separated and purified by the use of ion exchange chromatography. Sephadex chromatography and paper electrophoresis.The total number of amino acid residues in the Cowpea TMV protein was found to be 161 as opposed to the 158 found for the type TMV protein, and asparaginyl-arginine was the only tryptic peptide common to both proteins. All peptides used for mass spectrometry were first N-acetylated and then permethylated using methyl iodide and methyl sulphinyl carbanion or potassium t-butoxide dissolved in dimethyl sulphoxide.
    Additional Material: 1 Ill.
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  • 74
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Representative phenylalkylamines (six enantiomeric pairs) and amino acid methyl esters (five enantiomeric pairs) have been examined by gas chromatography-mass spectrometry, in the form of their N-(R)-α-phenylbutyryl, N-(S)-α-phenylpropionyl- and N-(R)-α-chlorophenylacetyl derivatives. In most cases, satisfactory gas chromatographic resolution of the diastereomeric amides has been achieved on both SE-30 and OV-17 stationary phases. The phenylbutyramides and phenylpropionamides gave the more informative mass spectra (for characterization of the amines) but molecular ions were observed in all instances.
    Additional Material: 4 Ill.
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  • 75
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    Biological Mass Spectrometry 1 (1974), S. 295-295 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 76
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Characteristic mass spectroscopic data for the identification of ten nitrosophenols is presented. The use of TMS derivatives for gas chromatography-mass spectrometry of 4-nitrosophenols is discussed, together with the use of copper chelates for obtaining direct insertion spectra of 2-nitrosophenols. The fragmentations of nitrosopher ols also show ions derived from their quinonemonoxime tautomers, even under gas chromatography-mass spectrometry conditions, indicating that isomerization occurs in the mass spectrometer. An anomalous elimination of nitrogen from these nitrosophenols has been shown to be a facile reduction of the nitroso moiety which takes place in the ion source of the mass spectrometer.
    Additional Material: 4 Ill.
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  • 77
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    Biological Mass Spectrometry 1 (1974) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 78
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mass fragmentographic method for the estimation of the estimation of free and bound morphine and free 6-monoacetylmorphine in blood has been developed. It uses stable isotope internal standards and has a sensitivity of about 1 ng per ml or about 100 times better than ordinary gas chromatography. The focusing on specific high molecular fragments of the molecules gives high specificity to the assay and the stable isotope internal standards allow correction for losses occuring in the preparative steps of the analysis. A sensitive, specific method for monoacetylmorphine is particularly valuable since this compound seems to be a specific metabolite of heroin.
    Additional Material: 11 Ill.
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  • 79
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nonvolatile biological materials, such as biopolymers or even whole cells, can be made accessible to mass spectrometric analysis by pyrolysis techniques. In principle, this enables differentiation, classification and identification of these materials. Moreover, pyrolysis mass spectrometry can provide a general picture of the chemical composition and structure of the sample analysed. During the past few years we have investigated several pyrolysis techniques in combination with different mass spectrometric methods. These investigations included Curie point pyrolysis, infrared laser pyrolysis, low voltage electron impact ionization, field ionizationIn co-operation with Professor Dr H. D. Beckey and Dr H.-R. Schulten, University of Bonn, Germany. and pyrolysis field desorption. Pyrolysis reactions were performed either at the gas inlet or directly at the ion source. The relative merits of these different experimental approaches are discussed. Additionally, examples of various applications, such as computer identification of bacteria and qualitative analyses of biopolymers, are given.
    Additional Material: 8 Ill.
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  • 80
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantitative methods based on chemical ionization mass spectrometry are described for the determination of tolbutamide, a sulfonylurea, and its metabolites from human plasma. The sulfonylureas are extracted from the acidified plasma and then N-1 methylated with diazomethane. The methylated compounds can be subjected to gas chromatography where they are partially cleaved to the corresponding N-1 methylated sulfonamides. Alternatively, the methylated compounds can be introduced into the ion source by means of a solid sampler. The sulfonylureas upon evaporation from the solid sampler or the formed sulfonamide and the parent sulfonylurea upon elution from the gas chromatographic column are subjected to chemical ionization with methane as the reactant gas. The [M + H]+ ions formed are measured quantitatively with respect to the deuterium substituted internal standards. It is suggested that the technique of introducing biological extracts into the ion source via a solid probe may be applied for the quantification of compounds that are unstable under gas-liquid chromatographic conditions. Both the gas chromatographic and the non gas chromatographic methods provided excellent and comparable results. The plasma level-time profile of tolbutamide and its metabolites in a diabetic patient following the administration of 1.0 g tolbutamide intravenously is presented.
    Additional Material: 11 Ill.
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  • 81
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of barbituric acids with diazoalkanes (diazomethane and diazoethane) gives the N,N′-dialkylbarbituric acids as the major products. Gas chromatograms of the reaction products show up to four additional peaks. These have been shown by mass and proton magnetic resonance spectrometry to be produced by the two isomeric N,O-dialkylbarbituric acids (1,4- and 1,2-dialkylbarbituric acids) and the two O,O′-dialkyl isomers.
    Additional Material: 7 Ill.
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  • 82
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    Biological Mass Spectrometry 1 (1974), S. 297-304 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fragmentation studies of the mass spectra of 24 high purity compounds of importance in a study of fossil fuels are described. The substances include eleven 1-(2-thienyl)-1-thia-, six1-(2-thienyl)-3-thia, and seven1-(2-thienyl)-4-thiaalkanes in the molecular weight range 158 to 270. Rearrangement peaks are prominent in all spectra and form the base peaks for the 1-thia- and 4-thia- compounds. The 3-thia- compounds are somewhat perverse in exhibiting weaker rearrangement peaks, and large ion intensities, including base peaks, at masses typical of alkyl fragments, alkenyl fragments, or ions more characteristic of the thiaalkanes (aliphatic sulfides). The major fragment ions are discussed and their use in differentiating subclasses is described. Low ionization voltage data is presented in support of suggested mechanisms of fragmentation.
    Additional Material: 3 Ill.
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  • 83
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for the quantification of phenformin, an oral hypoglycemic biguanide, from biological fluids based upon gas chromatography and chemical ionization mass spectrometry, is reported. Phenformin is quantitatively cyclized to the 2-substituted-4-trifluoremethyl-2,6-diamino-1,3,5-S-triazine when acylated with trifluoroacetic anhydride. This cyclized product was measured with respect to the deuterium substituted phenformin. The plasma levels achieved following the administration of a therapeutic dose of phenformin to a diabetic subject are reported.
    Additional Material: 4 Ill.
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  • 84
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On incubation with rat liver microsomes, N,N-dimethyl-5H-dibenzo[a,d]cycloheptene-Δ5,γ-propylamine is converted to the N-oxide. The identification of this metabolite has been achieved by the use of gas chromatography, mass spectrometry and thin-layer chromatography.
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  • 85
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    Biological Mass Spectrometry 1 (1974), S. 332-339 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three mass fragmentatographic methods for the determination of unconjugated estriol in pregnancy plasma and unconjugated and conjugated estriol in plasma of nonpregnant women after estriol administration were developed and tested as to their reliability and practicability. The methods were found to fulfil appropriate reliability criteria especially with regard to specificity. Unconjugated estriol could be assayed without prior chromatography in late pregnancy plasma, but a chromatographic step was needed for plasmas with a low estriol titre, and both a methylation step and chromatography is needed to achieve the required specificity if plasma conjugated estriol is determined or if assays are carried out following estriol administration. Unconjugated estriol in normal late pregnancy plasma was found in concentrations from 4.3 to 9.3 μg/l. The highest value recorded, 16.3 μg/l, was found in a prediabetic subject with mild hypertension, who delivered a child weighing 4150 g by Cesarean section in the 39th week. Low values were found in severe hypertension and in toxemia, and in general the results from the pathological material investigated seemed to correlate well with the clinical findings. However, only a few samples (five to ten) can be processed so rapidly that the results can be obtained the same day, which in addition to the expensive and complicated instrumentation limits the usefulness of the methods in routine clinical chemistry.
    Additional Material: 6 Tab.
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  • 86
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    Biological Mass Spectrometry 1 (1974), S. 350-351 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An unusual morphine analog was extracted and separated from an opium-like sample. The high resolution mass spectrum of the unknown substance confirmed the empirical formula as C17H18O2NCl. Mass spectra and retention factor values in thin-layer chromatography of both unknown and authentic standards were compared, which lead to the identification of the unknown as β-chloromorphide.
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  • 87
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    Biological Mass Spectrometry 1 (1974), S. 352-357 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two different mass spectrometric techniques have been used to analyse the products resulting from Curie-point pyrolysis of nucleic acids: low voltage ionization quadrupole mass spectrometry and high resolution field ionization mass spectrometry. The spectra obtained with both techniques are in good agreement with one another. As already indicated by the low resolution spectra, the high resolution spectra proved that most of the peaks originate from the carbohydrate moiety of the nucleic acid. Micrograms of DNA/RNA can be distinguished very easily by use of these key fragments, although the bases themselves are not found. Some significant pyrolysis mechanisms are proposed.
    Additional Material: 4 Ill.
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  • 88
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    Biological Mass Spectrometry 1 (1974), S. 358-362 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quantitative method for loading nanogram samples onto field desorption emitter wires is described. Sample consumption is reduced and problems with emitter wettability are overcome by freezing microliter droplets onto the emitters. Using this technique, good spectral data are obtained from 10 to 50 ng of material. Field desorption sensitivity measurements are reported for neomycin B, adenosine and cholesterol. Evaluation of the nonquantitative dipping technique previously employed reveals poor and nonreproducible sample loading efficiency.
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  • 89
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    Biological Mass Spectrometry 1 (1974), S. xv 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 90
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    Biological Mass Spectrometry 1 (1974), S. 365-366 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spark source mass spectrometry at a resolving power of up to 19 000 has been used to analyse an ashed human blood standard and an unknown animal blood for 28 elements.
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  • 91
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Biologically active primary amines (phenethylamines, amphetamines and tryptamines) form thermally stable isothiocyanate derivatives by reacting with carbon disulfide. Phenolic hydroxyl and indole (NH) nitrogens are further converted to their trimethylsilyl derivatives. The gas chromatographic and mass spectrometric properties of several amines are presented. It is shown that the combined use of gas chromatography and mass spectrometry of these derivatives is well suited for the differentiation of several structural isomers. Fragmentation mechanisms leading to the formation of structurally significant ions are discussed.
    Additional Material: 5 Ill.
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  • 92
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Piperidine is a putative neurotransmitter. Its sensitive determination is one of the prerequisites for the evaluation of its assumed physiological role. For its derivatization 5-di-n-butylaminonaphthalene-1-sulphonyl chloride, a new reagent which improves methods applying 5-dimethylaminonaphthalene-1-sulphonyl chloride, is used. Reaction of the perchloric acid tissue extract with this reagent, thin-layer chromatographic separation of the fluorescent derivatives and mass spectrometric evaluation of the di-n-butylaminonaphthalenesulphonyl piperidine spot by a version of the integrated ion current technique allows the determination of piperidine in tissues in picomole quantities. Standard deviation of the determinations of 2 to 16 pmol of piperidine added to 50 mg of brain tissue was ±8%. The method was applied to the analysis of different tissues. Brain concentrations of piperidine in different species were found to be lower by a factor up to 100 in comparison with published data.
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  • 93
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    Biological Mass Spectrometry 1 (1974), S. 415-417 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concentrations of carbon-13 in the individual carbon atoms of 3-hydroxy-2-butanone (acetoin) from apple cider vinegar decrease with decreasing oxidation level in the sequence .Because the distributions of isotopes within biological compounds are controlled by kinetic and equilibrium effects, intramolecular isotopic analyses may provide a means of defining the equilibria between metabolic pathways and of recognizing the molecular remnants of pre-existent organisms in geological samples.
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  • 94
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The minicomputer calculates and sets the required accelerating voltages by means of a 16 bit d.a.c. for maximum 8 masses within a 30% mass range. These, together with the t.i.c., are displayed in real time on a television screen and recorded on magnetic tape with a dynamic range of 1:32 000. Automatic fine adjustment of the mass focus and compensation for drifts in the magnetic field are some of the features in the mass fragmentographic package, which also allows data to be displayed, analysed, edited and plotted. Quantitative analyses can be handled entirely by the system if it is provided with the weight ratios of the compound to be determined and the standards to construct the standard curve. A table of the concentration per ml sample at the various times and/or a semi-log plot may be obtained by providing the amount of the standard added to the sample (e.g. blood), the extracted sample volume and the time at which the sample was drawn. Mass determinations of isolated or non-isolated compounds (nanogram amounts) can be performed within a few minutes with a precision usually better than 5 ppm employing a single focusing instrument at a resolution of 600-700. A maximum of seven unknown masses within a 30% range can be specified and determined simultaneously or in a preselected order. The shortest sweep time of the ion beam is 300 ms. The peak shapes can be analysed by displaying the data stored on magnetic tape on the television monitor.
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  • 95
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    Biological Mass Spectrometry 1 (1974), S. 418-422 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analog multiple ion detection system has been developed for magnetic sector mass spectrometers based on accelerating voltage alternation in conjunction with the accurate maintenance of focusing by means of voltage sweeping, using a superimposed a.c. sine wave voltage. This multiple ion detector voltage sweep system is easily constructed, inexpensive and produces analytical data of much greater precision than that reported from conventional systems. The application of the multiple ion detector voltage sweep system to biomedical problems is illustrated by the development of a method for the determination of stable isotope enrichment in blood glucose and alanine in children infused with tetradeuterio-L-alanine and dideuterioglucose to study gluconeogenesis and glucose utilization in vivo.
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  • 96
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    Biological Mass Spectrometry 1 (1974), S. 425-426 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of a macrocyclic ligand, such as a crown ether or cryptate, to the solution of an organic compound containing alkali metal ions prior to field desorption mass spectral analysis, has been shown to result in a reproducible, smooth field desorption process at low anode temperature. Crystalline dibenzo-18-crown-6 ether complexes of NaI and KI give field desorption spectra in which free and complexed ligands are of comparable intensity. Cryptate complexes retain the metal ion even more strongly, as illustrated by the fact that the complex of LiCl with [2.1.1]-cryptate yields almost exclusively the complexed lithium peak on field desorption. Alkali metal salts with organic anions also desorb more smoothly after complexation, although in the case of simple carboxylates the anion is found only in a cluster peak.
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  • 97
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    Biological Mass Spectrometry 1 (1974), S. x 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 98
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    Biological Mass Spectrometry 1 (1974), S. 1-4 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two major metabolites of [14C]niflumic acid, 2-(3′-[14C] trifluoromethylanilino)nicotinic acid have been isolated from human urine. Low and high resolution mass spectrometry indicate that both metabolites (M2a and M2b) are monohydroxylated derivatives of niflumic acid. The 100 MHz proton magnetic resonance spectrum of M2b demonstrates it to be 5-hydroxyniflumic acid, whereas M2a is either the 4′- or 6′-hydroxy derivative. The synthesis of 6′-methoxyniflumic acid methyl ester and comparison of its spectral data and melting point with that of the corresponding derivative of M2a reveal their non-identity. The structure of M2a is, therefore, 4′-hydroxyniflumic acid.
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  • 99
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    Biological Mass Spectrometry 1 (1974), S. 5-9 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The field ionization and electron impact mass spectra of eleven coumarins have been compared. In the field ion spectra the molecular ions were the base peaks and structurally diagnostic fragment ions formed by direct cleavage were present, whereas the molecular ions were weak in the electron impact spectra and fragment ions formed by rearrangement were dominant. Crude coumarin mixtures obtained from natural sources have been successfully examined using field ionization and gas chromatography + field ionization mass spectrometry.
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  • 100
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amino acid sequence in Cyl-2, a biologically active cyclotetrapeptide from Cylindrocladium scoparium, was investigated. Through high resolution mass spectrometry along with application of the defocusing technique, the structure of cyl-2 was determined as cyclo-D-O-methyltyrosyl-L-isoleucyl-L-pipecolyl-2-amino-8-oxo-9, 10-epoxydecanoyl.
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