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  • Analytical Chemistry and Spectroscopy  (25,033)
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  • 1
    Electronic Resource
    Electronic Resource
    Vibrational dephasing of the ν3 mode of liquid allene (1986)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 17 (1986), S. 477-480 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectrum of the ν3 mode of allene has been studied as a function of temperature throughout the temperature range of the liquid. Analysis of the spectral band shape shows that the vibrational dephasing is a fast-modulation process. Evidence is presented for a vibrational-rotational coupling involving the tumbling reorientation of the molecule. Dilution studies in GeH4 indicated significant resonant vibrational energy transfer.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250170610
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of benzene alkyl derivatives in heavily loaded environmental aqueous samples by means of combination of distillation and purge and trap-gas chromatography-mass spectrometry (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 482-486 
    Details
    ISSN: 0935-6304
    Keywords: Volatile benzene alkyl derivatives ; Simple distillation ; Purge and trap ; Capillary gas chromatograph-mass spectrometry ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simple distillation was used to prepare aqueous environmental samples (especially those with high content of accompanying dissolved and suspended organic and inorganic matter) for determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) by means of purge and trap (PT) coupled to gas chromatography-mass spectrometry (GC-MS). The PT step was carried out with a laboratory-built device in which alalytes desorbed from a Primary trap (macrotrap) are focused in a microtrap (also with sorbent) and moisture is removed from purge gases by a Nafion tube (walls selectively permeable to water vapor). Recoveries, if only the first 10 ml distillate was collected, were of the order of 40% at optimum distillation parameters. At a probability level of 95% recoveries were independent of concentration in a studied concentration range of 0.50-30 ppb. Enrichment factors for distillation were of the order off 20. Real samples, i.e., raw and treated waste water were analyzedc for BTEX content by the developed medthod.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200904
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  • 3
    Electronic Resource
    Electronic Resource
    An energy-resolved study of the fragmentation of ionized 1-Penten-3-ol (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1984), S. 573-576 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed energy-resolved study of the fragmentation of CH2=CHCH(OH)CD2CD3 (1-d5) has been carried out using metastable ion studies and charge exchange techniques, combined with collision-induced dissociation studies to establish the structures of fragment ions. At low internal energies (metastable ions) the molecular ion of 1-d5 rearranges to the 3-pentanone structure and fragments by loss of C2H5 or C2D5 leading to the acyl structure, [CH3CH2C≡O]+ or [CD3CD2C≡O]+, for the fragment ion. However, with increasing internal energy of the molecular ion this rearrangement process decreases rapidly in importance and loss of C2D5 by direct cleavage, leading to [CH2=CHCH=OH]+, becomes the dominant fragmentation reaction. As a result the [C3H5O]+ ion seen in the electron impact mass spectrum of 1-penten-3-ol has predominantly the protonated acrolein structure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210191109
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  • 4
    Electronic Resource
    Electronic Resource
    A 15N labelling, FD and FAB study of ammonia loss from protonated arginine molecules (1983)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1983), S. 525-529 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive ion field desorption (FD) spectrum of arginine taken at the best anode temperature only contains a peak due to [M+H]+ ions. At higher emitter temperatures a considerable amount of fragmentation is induced and the [M+H—NH3]+ ions become most abundant. Specific 15N labelling reveals that the eliminated ammonia molecule, exclusively, contains one of the terminal nitrogen atoms of the guanidyl group. This also applies to the ammonia loss from metastably decomposing [M+H]+ ions. The positive ion fast atom bombardment (FAB) spectrum shows more fragmentation than the FD spectrum. In contrast with the FD results, the [M+H]+ ions generated upon FAB with ion lifetimes 〈10-6 s eliminate both ammonia containing one of the terminal nitrogen atoms of the guanidyl group and ammonia containing the α-amino group in the ratio of 1.35, as found by 15N labelling. The metastably decomposing [M+H]+ ions, however, eliminate only the former ammonia molecule. In the negative ion FD and FAB spectra no other peak than that corresponding to the [M—H]- ion is observed. Some attention has been paid to the thermal degradation of arginine on the basis of a few Curie-point pyrolysis experiments.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210181206
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  • 5
    Electronic Resource
    Electronic Resource
    Negative ion field desorption mass spectrometry by clustering with anions (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 312-315 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that under field desorption conditions some less volatile or non-volatile compounds such as oligosaccharides, sulphonic acids and fatty acids can be ionized below the threshold of field electron emission by clustering with anions. In all cases the sample, together with polyethylene oxide 4000, is dissolved in water. The source of the clustering anion is provided either by a small amount of a salt added to this solution (sugars) or by the compounds themselves (sulphonic and fatty acids). The solution is applied to unactivated and/or slightly activated 10 μm tungsten wire cathodes. Suitable clustering ions for the sugars appear to be [Cl]-, [NO3]- and to a lesser extent [Br]- and [I]-. Most of the sulphonic acids studied give rise to the formation of [Mn - H]- ions (n≤5), but their potassium salts yield only unclustered sulphonate anions. However, the addition of a small amount of LiCl to the mixture of benzene sulphonic acid and polyethylene oxide 4000 promotes the formation of clustered anions, [(M - H)2Li]- being by far the most abundant if activated cathodes are used. This addition of some LiCl is essential in the case of fatty acids: without LiCl no anions may be desorbed at all from activated wires, but with the presence of LiCl both [M - H]- and the most abundant [(M - H)2Li]- anions are easily generated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200080706
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  • 6
    Electronic Resource
    Electronic Resource
    Biodegradation of Pharmaceutical Residues Investigated by SPE-GC/ITD-MS and On-Line Derivatization (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 474-478 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Solid-phase extraction, on-line derivatization, and measurement by ion trap mass spectrometry (ITD-MS) were used to investigate the biological degradation of pharmaceutical residues (clofibric acid, ibuprofen, diclofenac). The results of the single steps of sample pretreatment and analytical determination are reported. MS/MS measurements were performed on an ITD-MS by selecting collision induced dissociation of the molecular ions (M+) as parent ions to defined daughter ions. A pilot sewage plant and biofilm reactors operating under oxic and anoxic conditions were run as model systems with synthetic sewage water containing 10 to 50 mg/L dissolved organic carbon (DOC) and pharmaceuticals in concentrations of 10 μg/L. Clofibric acid displayed its persistent character in all cases. The pilot sewage plant and the oxic biofilm reactor showed comparable results for diclofenac and ibuprofen, which both were partly degraded. These results can explain the occurrence of these substances in sewage effluents and in the aquatic environment. A high degree of degradation was found especially for ibuprofen in the oxic biofilm reactor, which was attributed to adaptation of the biofilm to the residue. Two metabolites of ibuprofen could be identified on the basis of their mass spectra and comparison with literature data, viz. hydroxyibuprofen and carboxyibuprofen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Low wavenumber Raman scattering in viscous liquids (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 25 (1994), S. 849-854 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Low-wavenumber depolarized Raman spectra (-400 to 400 cm-1) for dioxane, water and glycerol are presented. Stokes and anti-Stokes spectra (-400 to 400 cm-1), are used to define a reduced spectrum, in which the effects of temperature and also flat backgrounds and symmetric central components are removed, without knowledge of these parameters. Comparison with the usual reductions shows that (i) all inelastically scattered photons must be considered as ‘true’ Raman signals, due to processes involving Boson-like excitations, (ii) if central scattering exists, then its intensity also depends on the population factor, (iii) the low-wavenumber Stokes signal is more intense than expected for a factor of n + 1 only, owing to non-linear effects, and (iv) the systematic use of reduced spectra is not essential, and can be hazardous in some cases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250251102
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  • 8
    Electronic Resource
    Electronic Resource
    Gas chromatographic analysis of estrogens from pregnant mares' urine using glass capillary columns (1980)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 169-171 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Glass capillary columns ; Trimethylsilyl derivatives ; Pregnant mares' urine estrogens ; Estrone-equilin separation ; OV-225, Silar 10C stationary phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillary columns coated with OV-225 and Silar 10C were used to analyze estrogens (as their trimethylsilyl derivatives) present in pregnant mares' urine. Such columns provide better resolution in a shorter time than the corresponding packed columns, as exemplified by the separation of estrone from equilin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240030404
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  • 9
    Electronic Resource
    Electronic Resource
    Electron paramagnetic resonance and Mössbauer studies of metal chelation by adriamycin (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. S114 
    Details
    ISSN: 0749-1581
    Keywords: electron paramagnetic resonance ; adriamycin ; metal chelation ; coordination structure ; iron ; free radical ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: EPR and Mössbauer studies demonstrate that iron chelation by adriamycin is complex, with several different chelation structures. At physiological pH in aqueous solution, three different EPR spectra are observed: a spectrum at g = 4.2 of Fe3+ in a rhombic crystal field (type 1); a spectrum at g = 2.01 with symmetric Gaussian lineshape linewidth 225 G (1 G = 10-4 T), suggestive of Fe3+ bound in an octahedral crystal field (type 2); and a broad spectrum centered at g = 2.0 suggestive of ferromagnetically coupled Fe3+ (type 3). The type 1 and 2 spectra are observed at adriamycin/Fe3+ ratios 〉4, the type 3 spectrum is observed at ratios 〈4 and at ratios 〈2 an increasing amount of Fe3+ gives rise to EPR silent iron(III) hydroxide polymers. At 4 K the type 1 and 2 complexes exhibit a broad doublet Mössbauer signal with an isomer shift δ = 0.56 (1) mm s-1 and quadrupole splitting δEQ = 0.74 (1) mm s-1. The type 3 complex gives rise to a sextet signal with isomer shift ΔEq = 0.47 (1) mm s-1 and hyperfine splitting HF = 476 (1) kG with exhibits superparamagnetic relaxation behavior with a blocking temperature of 23 K, consistent with a microcrystal size of 25 Å. Cu2+ binds to adriamycin at adriamycin/Cu2+ ratios 〉4:1 giving rise to an EPR spectrum with axial symmetry g∥ = 2.26, g⊥ = 2.066, A∥ = 188 G, while 2:1 complexes exhibit a single Gaussian line at g = 2.09 indicative of exchange-coupled Cu2+. The exchange-coupled Cu2+ and ferromagnetically coupled Fe3+ complexes can be explained by the formation of stacked 2:1 adriamycin-metal polymers. On titration of adriamycin with Fe3+-nitrilotriacetate a different spectrum is observed at g = 4.3 and its intensity plateaus at an adriamycin/iron ratio of 2. The iron adriamycin complexes cycle to reduce molecular oxygen and this cycle has been hypothesized to be a mechanism mediating the therapeutic and toxic effects of the drug. Both EPR and Mössbauer experiments demonstrate that the type 1 and 2 chelates reduce their Fe3+ to Fe2+ while the type 3 chelate does not. Therefore, the stoichiometry and method of complex preparation can profoundly effect the properties of these complexes.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260331318
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  • 10
    Electronic Resource
    Electronic Resource
    Combined Cl and El mass spectra in the analysis of essential oils (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 510-513 
    Details
    ISSN: 0935-6304
    Keywords: GC-MS ; Cl ; El ; Flavors ; Cola beverages ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As part of a study directed at introducing GMP recommendations to the production of non-alcoholic beverages, combined Cl and El mass spectra have been used for the identification of compounds present in extracts of “Cockta” beverage following GC-MS analysis. The amount of useful information present both in the separate Cl and El spectra, and in two of the possible combinations of the spectra, is described.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240150805
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