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  • 1995-1999  (164)
  • 1970-1974
  • 1998  (164)
  • Analytical Chemistry and Spectroscopy  (163)
  • Nuclear reactions
Materialart
Erscheinungszeitraum
  • 1995-1999  (164)
  • 1970-1974
Jahr
  • 101
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 161-170 
    ISSN: 1075-4261
    Schlagwort(e): surface-enhanced resonance Raman scattering ; SERRS ; cytochrome c3 ; electrode modifiers ; electroreflectance voltammetry ; ER ; 11-mercaptoundecanoic acid ; 4,4′-bipyridine promoters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Surface-enhanced resonance Raman scattering and electroreflectance voltammetry were used to investigate the effect of electrode surface modification on the structure and redox properties of cytochrome c3 immobilized on Ag surfaces. It is shown that the redox reactions of cytochrome c3 are more reversible at an 11-mercaptoundecanoic acid modified Ag electrode as compared to a bare metal surface. The heme of cytochrome c3 is in a mixed low and high spin state when adsorbed at the bare electrode, whereas only the low spin form is present on the 11-mercaptoundecanoic acid modified electrode, suggesting that the native conformation is maintained in the latter case. The reduction potential is close to that of the most positive macroscopic potential as determined by electroreflectance spectroscopy. In contrast, the reduction potential as determined by SERRS undergoes a large positive shift in the presence of 4,4′-bipyridine, the magnitude of which is dependent upon the concentration of 4,4′-bipyridine. These results indicate that the effect of the cytochrome c3 interaction with the 4,4′-bipyridine-modified surface is significantly different as compared to its interaction with the 11-mercaptoundecaodoic acid modified surface. Moreover, the results emphasize that electrode modifiers can have dramatically different effects on the redox properties of different proteins. It is well known that 4,4′-bipyridine acts as a redox promoter in the case of cytochrome c, whereas no electrochemical or electroreflectance response was observed in the case of cytochrome c3. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 161-170, 1998
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 102
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 185-195 
    ISSN: 1075-4261
    Schlagwort(e): hydrogen bonding ; van der Waals ; betacarbolines ; benzopyridines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: A spectroscopic (UV-vis, Fourier transform IR, steady state, and time-resolved fluorescence) study of the interactions of the ground and excited singlet states of harmane (1-methyl-9H-pyrido/3,4-b/indole) with quinoline has been carried out in cyclohexane, toluene, and buffered pH = 8.7 aqueous solutions. To analyze how the number of rings in the substrate influences these interactions, pyridine and phenanthridine have also been included in this study. In cyclohexane and toluene 1 : 1 stoichiometric hydrogen-bonded complexes are formed in both the ground and the excited singlet states. As the number of rings of the benzopyridines and the solvent polarity increase hydrogen-bonding interactions weaken and π-π van der Waals interactions become apparent. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 185-195, 1998
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 103
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 171-184 
    ISSN: 1075-4261
    Schlagwort(e): ultraviolet resonance Raman spectroscopy ; membrane-bound peptides ; gramicidin A ; ion channel ; tryptophan orientation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: A Raman linear intensity difference (RLID) method has been developed to determine orientations of chromophores in membrane-bound peptides and proteins. The method involves orientation of the peptide or protein in lipid bilayer membranes and measurement of intensity differences between Raman spectra excited with two orthogonal laser polarizations. Analysis of the RLID spectrum is simplified when the chromophore exhibits a vibrational mode for which the Raman band is enhanced through resonance with a single molecular electronic transition. To examine the indole ring orientations of Trp residues in the gramicidin A transmembrane channel, we have prepared analogues of gramicidin A, in which one of four Trp residues is replaced by deuterated Trp (Trp-2,4,5,6,7-d5). Two vibrational Raman bands ωd3 and ωd2 of deuterated Trp have been shown to gain intensity predominantly through resonance with the Bb and La electronic transitions, respectively, when excited at 244 and 257 nm. By examining the RLID spectra of the ωd3 and ωd2 bands of gramicidin A channels oriented in phospholipid bilayer membranes, we have determined the inclination angles of the Bb and La transition moments with respect to the channel axis in the absence and presence of Na+. The orientations of the Trp-11 and Trp-13 indole rings in the gramicidin channel structure have been derived from the inclination angles of the transition moments. The indole rings of Trp-11 and Trp-13, which are known to shift along the channel axis upon binding of Na+, do not reorient during their positional shifts. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 171-184, 1998
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 104
    ISSN: 1075-4261
    Schlagwort(e): dipalmitoylphosphatidylcholine ; dioleoylphosphatidylcholine ; mixed-chain phospholipids ; unsaturation ; hydration ; FTIR spectroscopy ; lyotropic phase transition ; chain-melting transition ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: An algorithm for the study of the gradual hydration of phospholipid assemblies by means of Fourier transform infrared (FTIR) spectroscopy is presented. A complete series of diacyl phosphatidylcholines (PCs) including all possible analogues with palmitoyl and oleoyl residues, namely DPPC, DOPC, POPC, and OPPC, was investigated at room temperature. The lipid samples were prepared as cast films probably consisting of aligned multilamellar bilayers. The range of water activities studied in these films was regulated by adsorption via the gas phase corresponding to relative humidities of between 0 and 100%. Analyses of the IR-spectroscopic data have concentrated mainly on determining the amounts of water incorporated by each lipid as well as the hydration-induced response observed for some absorption bands of the different lipids. The water uptake at high relative humidity (RH) increases with the portion of unsaturated acyl chains in the molecular structure of the PCs. Isothermal phase transitions triggered lyotropically have been detected in demonstrating the occurrence of the main transition in POPC and OPPC films at room temperature. Moreover, it appears that both lamellar phases, the gel as well as the liquid-crystalline phase, are not uniform. They seem to comprise an amazingly large span of order/disorder states of the lipid chains generally depending on the degree of hydration. As exemplified by the significant variation in the onset of wavenumber shifts for the PO2- and C=O stretching-vibration modes, obtained as a function of hydration, a sequence of attachment to polar lipid binding sites by water molecules was established for DPPC. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 267-280, 1998
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 105
    ISSN: 1075-4261
    Schlagwort(e): photon migration ; ballistic photons ; two-photon excitation ; fluorescence ; time-resolved fluorescence ; optical tomography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: We describe spatially localized two-photon excitation in scattering media. Using femtosecond pulses at 770 nm from a Ti : Sapphire laser, we were able to excite fluorophores in capillary tubes under up to 1.5 mm of 0.5% intralipid. Displacement of the laser beam relative to the embedded samples indicates that highly localized excitation was possible with two-photon excitation, whereas one-photon excitation resulted in loss of spatial resolution due to excitation by the diffusely scattered photons. These results indicate that two-photon excitation in the scattering solution is due only to the ballistic photons, a result confirmed by frequency-domain time-resolved measurements. Selective excitation of adjacent embedded samples was found possible for two but not one-photon excitation. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 303-310, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 106
    ISSN: 1075-4261
    Schlagwort(e): 9-aminoacridine ; fluorescence ; SERS ; dimerization ; excimer ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Fluorescence spectroscopy and surface-enhanced Raman spectroscopy (SERS) have been applied to study the aggregation and excimer emission of 9-aminoacridine (9AA) and 9-aminoacridine hydrochloride (9AA-HCl) in aqueous solution and on silver colloids. The effect of the drug concentration, pH, and chloride concentration on these processes has been investigated. The excimer emission of 9AA is connected to the dimerization of this drug in solution: the formation of 9AA dimers is greatly favored when the drug is under the amino form at neutral and acidic pH, while at alkaline pH the imino 9AA form tends to form large-sized aggregates which cannot be excited to render excimer emission. 9AA is adsorbed on the silver surface under two different forms: strongly and weakly attached 9AA, each one corresponding to the different drug tautomers: imino and amino. The interaction of 9AA with silver induces a charge transfer from the adsorbate to the metal leading to a remarkable fluorescence quenching, a basicity decrease of the adsorbed drug and a considerable weakening of the dimer-excimer emission. Furthermore, an attribution of the main Raman features appearing in the SERS spectra has been proposed, providing marker bands for the imino and amino 9AA tautomers, and a mechanism for the molecular dimerization is also suggested. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 327-339, 1998
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 107
    ISSN: 1075-4261
    Schlagwort(e): molecular force field ; resonance Raman intensities ; aromatic amino acids ; nucleic acid bases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Normal modes analyses for different molecules with biological interest have been performed and checked via the calculation of resonance Raman intensities. For this purpose, molecular orbital calculations were used to determine bond order changes in the lowest-lying electronic transitions. These bond order changes were used to calculate resonance Raman intensities in order to obtain correct vibrational assignments and reliable force fields. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 379-393, 1998
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 108
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 403-412 
    ISSN: 1075-4261
    Schlagwort(e): FT Raman microscopy ; qualitative analysis ; bone mineralization ; hydroxyapatite coatings ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: An optimized FT Raman microscope (inverted microscope with high throughput of radiation) was developed that allows minimal sample preparation and Raman spectroscopy without fluorescence. A quantitative determination of the mineralization of bone tissue and hydroxyapatite (HA) coatings of hip and knee prostheses was performed. The lateral resolution reached down to 10 μm. The distribution of the HA content in the coatings investigated was found to be similar all the time. This result was independent of the composition of the coatings and the history of the whole prosthesis. In the immediate vicinity of the prosthesis a large HA content could be observed that decreased to a minimum towards the periphery of the coating and increased at the site of the ongrown bone. For the interface between bone and HA coating a transitional zone was observed at a lateral distance of 30-40 μm to the implant. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 403-412, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 109
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. S1 
    ISSN: 1075-4261
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: No abstract.
    Materialart: Digitale Medien
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  • 110
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. S31 
    ISSN: 1075-4261
    Schlagwort(e): stratum corneum ; epidermis ; noninvasive ; lipids ; natural moisturizing factor ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Noninvasive techniques that provide detailed information about molecular composition, structure, and interactions are crucial to further our understanding of the relation between skin disease and biochemical changes in the skin, as well as for the development of penetration enhancers for transdermal drug administration. In this study we present in vitro and in vivo Raman spectra of human skin. Using a Raman microspectrometer, in vitro spectra were obtained of thin cross sections of human skin. They provided insight into the molecular composition of different skin layers. Evidence was found for the existence of a large variation in lipid content of the stratum corneum. A simple experimental setup for in vivo confocal Raman microspectroscopy of the skin was developed. In vivo Raman spectra of the stratum corneum were obtained at different positions of the arm and hand of three volunteers. They provided evidence for differences in the concentration of natural moisturizing factor at these positions. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: S31-S39, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 111
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 17-25 
    ISSN: 1075-4261
    Schlagwort(e): DNA dyes ; single-stranded DNA ; oxazole yellow ; fluorescent dyes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Interactions between short single-stranded DNA oligomers of homogeneous base composition and the fluorescent probes oxazole yellow (YO) and its homodimer YOYO are described. The oligomers included 15-mers and 30-mers of polydA, polydT, polydG, and polydC. Interactions between the dyes and DNA hybrids formed from complementary homogeneous strands of equal length were also investigated. No interactions were observed between the dyes and the monomeric monophosphate nucleosides A, G, T, or C. The dyes were found to interact much more strongly with the purine oligomers polydA and polydG than with the pyrimidine oligomers polydT and polydC. PolydA of both lengths has strong interactions with YOYO, whereas the polydG 30-mer interacts strongly with monomeric YO. The 15-mers of polydG and polydC of both lengths show little interaction with either dye. Interactions of the dyes with the polydA/polydT and polydG/polydC hybrids tend to be dominated by interactions with polydA and polydG, respectively. Although dye interactions generally were facilitated by hybridization, particularly for polydA/polydT, the interactions were similar to those with the single strands and different from those that have been observed in long double-stranded DNA. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 17-25, 1998
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 112
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 27-35 
    ISSN: 1075-4261
    Schlagwort(e): DNA dyes ; single-stranded DNA ; oxazole yellow ; fluorescent dyes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Interactions between short single-stranded DNA ligands and fluorescent DNA indicator dyes were used to investigate binding selectivity of the ligands. Conformational differences among four DNA ligands of different sequence and structure, including two that form a G-quartet and two that do not, were confirmed by circular dichroism spectroscopy. Their interactions with indicator dyes YO-pro-1 iodide (YO) and YOYO-1 iodide (YOYO) were probed using measurements of dye absorbance; induced circular dichroism; and fluorescence spectra, anisotropy, and lifetime. Equilibrium binding constants and stoichiometry were determined as well. Results indicate significant differences among the dye interactions and binding stoichiometries of the four ligands. One of the G-quartet forming ligands, a 20-mer of sequence 5′-GGTTTT-GGTTTTGGTTTTGG-3′, shows distinctly different interactions from the other three ligands, all of which are 15-mers. These studies illustrate the importance of sequence and conformation in determining the binding interactions of short single-stranded DNA. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 27-35, 1998
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 113
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 37-46 
    ISSN: 1075-4261
    Schlagwort(e): FTIR ; cancer prognosis ; cancer grade ; tissue spectroscopy ; lymphoma ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Thirty-nine freeze-dried tissue samples from 17 lymphoid tumors (nine malignant non-Hodgkin's lymphomas) were studied by Fourier transform infrared (FTIR) spectroscopy. The absorbance ratio A1121/A1020 increased, along with the emergence of an absorbance pulse at 1121 cm-1, with increasing clinicopathological grade of malignant lymphoma. An increasing A1121/A1020 ratio from benign to malignant is evident in literature spectra from several different tissues; however, the present study is the first to comment on this effect and to propose it as an index of the cellular RNA/DNA ratio after subtraction of overlapping absorbances, if present, due to collagen or glycogen. Absorbance attributable to collagen increased with lymphoma grade and was greater in benign inflammatory tumors than in low-grade lymphomas. The A1121/A1020 trend observed here may form the basis of a universal cancer-grading parameter to assist with cancer treatment decisions and may also be useful in the analysis of cellular growth perturbation induced by drugs or other therapies. Our spectral findings may potentially be applied to cell clusters and discrete areas of tumor tissue sections using the FTIR microscope, allowing correlation with morphology and a high degree of spatial resolution. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 37-46, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 114
    ISSN: 1075-4261
    Schlagwort(e): cytochrome ba3 ; cytochrome aa3 ; binuclear site structure ; cyanide ; Raman spectroscopy ; normal coordinates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: The cyanide isotope-sensitive low-frequency vibrations of ferrous cyano complexes of cytochrome a3 are studied for cytochrome ba3 from Thermus thermophilus and cytochrome aa3 from bovine heart. Cyanide complexes of ba3 display three isotope sensitive frequencies at 512, 485, and 473 cm-1. The first is primarily an Fe - C stretching motion, whereas the lower wavenumber modes are bending motions. These iron-cyanide vibrations are independent of the redox levels of the other metal centers in the protein. On the other hand, the fully reduced bovine derivative complexed with cyanide gives rise to a bending vibration at 503 cm-1 and a stretching vibration at 469 cm-1. That is, the ordering of the stretching and bending frequencies is reversed from that of the bacterial protein. These results are analyzed by normal coordinate calculations to obtain comparative models for the binuclear O2 reducing site of the two proteins. We find that the observed frequencies are consistent with a linear Fe - C - N group and larger Fe - C stretching force constant (2.558 mdyn/Å) for ba3 and a slightly bent Fe - C - N group (angle ∼ 170°) and a smaller Fe - C stretching force constant (2.335 mdyn/Å) for aa3. Thus, there are significant differences in the interaction of cyanide with ferrous a3 in the two proteins that are most likely caused by a weaker proximal histidine interaction and stronger peripheral heme electron withdrawing effects in ba3. Possible sources of these protein-induced effects are discussed. Using the analysis developed here, comparison of the FeCN stretching and bending frequencies of the ferrous bovine a3-CN complex to those obtained from the ferric a3-CN complex suggests that upon conversion of the resting to the fully reduced protein, a conformational change occurs that constrains the ligand binding site. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 1-15, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 115
    ISSN: 0935-6304
    Schlagwort(e): gas chromatography ; sorptive preconcentration ; air sampling ; VOCs ; nitro-PAH's ; PAHs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---This paper is concerned with the determination of volatile and semi-volatile organic components in air and gaseous (headspace) samples, focusing primarily on polar analytes. Samples were analyzed by preconcentration on different (ad)sorbents followed by thermal desorption and analysis by capillary gas chromatography. The performance of a cartridge filled with 100% polydimethylsiloxane (PDMS) particles was compared to that of adsorbents like Tenax TA and Carbotrap 300. Though the PDMS phase is non-polar it showed adequate retention for both polar and non-polar components. The blank runs of the PDMS trap were significantly better than those of most adsorbents and did not deteriorate, as was the case with all the conventional adsorbents investigated. With respect to trapping efficiencies, the PDMS phase performed better for most of the analytes under investigation compared to the adsorbents. For a range of analytes including triethylamine, butanone, diacetyl, nicotine, and acetic acid the PDMS phase performed exceptionally well whereas all adsorbents showed unsatisfactory performance. The packed PDMS traps were employed for the determination of organic acids, PAH's and nitro-PAH's in air and for the analysis of the headspace of cacao and hop.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 116
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 347-354 
    ISSN: 0935-6304
    Schlagwort(e): Fragrances ; chirality evaluation ; semi-automated multidimensional gas chromatography ; infrared spectrometry ; mass spectrometry ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The use of a semi-automated, multidimensional gas chromatography (MDGC) Fourier transform infrared (FT-IR) mass spectrometry (MS) system in the determination of components causing contact dermatitis has been investigated. Fragrances are widely used in cosmetic and household products and are the leading cause of contact dermatitis. Such products contain numerous components such as emulsifiers, thickeners, solubilizers, pigments, antioxidants, and many other compounds, which can make it difficult to isolate the compound of interest. MDGC has the capability for component analysis in such complex matrices. A semi-automated MDGC system, which consists of a commercial instrument modified in our laboratory to include two computer controlled valves and a single trap which is manually controlled was evaluated for analysis of irritants in a total of thirteen soaps. Using heartcutting techniques, components causing dermatitis were identified in eight of the thirteen soaps by examining both the infrared and mass spectra obtained and matching them with computer spectral libraries. Results from these analyses show that a baby soap and three other mild soaps were free of irritants. Irritants were identified in the remaining eight soaps. In addition, to demonstrate the versatility of the semi-automated system, the enantiomeric composition of a chiral irritant in two soaps also was determined.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 117
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 368-370 
    ISSN: 0935-6304
    Schlagwort(e): Solid-phase microextraction ; headspace analysis ; gas chromatography ; mass spectrometry ; volatile analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 118
    ISSN: 0935-6304
    Schlagwort(e): chemiluminescence detector ; guava ; MDGC ; 2-pentanethiol ; Psidium guajava ; SCD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 119
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 378-382 
    ISSN: 0935-6304
    Schlagwort(e): Large volume injection ; on-column injection ; flooded zone ; solvent trapping ; temperature measurement on precolumn wall ; water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Solvent trapping reconcentrates volatile components after injection or on-line transfer of large volumes. When an early vapor exit is used, typically after a 5-10 m × 0.53 mm i.d. uncoated precolumn, the solvent trapping process differs from that described previously. The visual experiments and the conclusions drawn therefrom, as described in a previous paper, are supplemented with chromatographic results. They show that even hexane can be quantitatively analyzed in 250 μl of a pentane solution. Injection of a volume of 250 μl by vaporizer/precolumn solvent splitting was used in the analysis of gasoline in drinking water. Conditions for the transfer of a 1000 μl volume can easily be adjusted through detection of the front end of the flooded zone by a thermocouple mounted on the outer wall of the precolumn.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 120
    ISSN: 0935-6304
    Schlagwort(e): high temperature gas chromatography ; flavonoids ; propolis ; high molecular weight compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The underivatized acetone and hexane fractions from propolis samples (predominant flora Citrus spp. and Vernonia polyanthes) were analyzed by HT-HRGC (high temperature high resolution gas chromatography) and HT-HRGC coupled to mass spectrometry (HT-HRGC-MS). Several compounds, including flavonoid aglycones, phenolic acids, and high molecular weight compounds were characterized in crude extracts by HT-HRGC-MS. HT-HRGC and HT-HRGC-MS were shown to be quick and informative tools for rapid analysis of crude extracts without need for prior derivatization and purification.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 121
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 411-413 
    ISSN: 0935-6304
    Schlagwort(e): Modulator ; GC x GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 122
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 401-406 
    ISSN: 0935-6304
    Schlagwort(e): capillary electrophoresis ; Turkey Red Oil ; surfactants ; industrial process water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A method using capillary electrophoresis with direct UV detection has been developed and validated for the determination of Turkey Red Oil (sulfonated castor oil). The highest performance with respect to separation efficiency and analysis time was achieved with 30 mM Tris (pH 8.0) buffer containing 7.5 mM HP-β-CD. The feasibility of the proposed CE method for the analysis of Turkey Red Oil surfactant in industrial water samples is demonstrated. Spiking of real samples gave recoveries between 90 and 106%. The CE results were compared with that obtained by GC-MS. It was concluded that CE can be a good alternative for fast determination of Turkey Red Oil component distribution in industrial process waters with no sample preparation other than dilution. However, the method sensitivity is not satisfactory for monitoring surfactant level in a waste effluent stream.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 123
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 417-420 
    ISSN: 0935-6304
    Schlagwort(e): capillary gas chromatography ; dihydrotestosterone esters ; dihydroepitestosterone esters ; Kováts retention indices ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 124
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 649-652 
    ISSN: 0935-6304
    Schlagwort(e): capillary gas chromatography ; NPD ; nicotine ; pharmaceutical analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The delivery of drugs through human skin using transdermal drug delivery (TDD) systems has become an established technology. A popular drug with that dosage form is nicotine for smoking cessation. A stability indicating method for the analysis of nicotine TDDs using gas chromatography (GC) with post-column effluent splitting to a flame ionization detector (FID) and a nitrogen-phosphorus detector (NPD) is described. FID detection gave reliable results with low day-to-day variability. The detector is relatively simple to operate. NPD detection offered enhanced sensitivity and specificity. The combination of both detectors resulted in a rugged method for content analysis with high sensitivity for detection of degradation products at low concentration levels. Despite a relatively simple sample preparation procedure no matrix interferences were observed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 125
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 665-666 
    ISSN: 0935-6304
    Schlagwort(e): SPME; GC/MS ; Hg2+ and CH3Hg+ urine samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 126
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 25-31 
    ISSN: 0935-6304
    Schlagwort(e): Photo-tunable chromatography ; semi-micro HPLC ; photochromic compounds ; azobenzene ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---To develop photo-tunable chromatography, several azobenzene derivatives were immobilized or modified on silica gels or incorporated into polymers. The supports prepared were used as stationary phases in semi-micro HPLC, and the photo-dependence of their retention evaluated. On these stationary phases, the retention measured with 2-propanol in hexane was increased by UV irradiation; in contrast, the retention was decreased when methanol was used as mobile phase. It was assumed that the polarity of the stationary phase increases when the molecular structure of the azobenzene moieties changes from the trans to the cis form. On irradiation of the column with visible light after UV irradiation and with methanol as mobile phase, the change of retention proved to be reversible. However, this reverse change was less dramatic than the initial change. Such retention behavior is attributable to photo-isomerization of the azobenzene moieties. These findings will be exploited in our development of new photo-tunable stationary phases and new photo-controlled separation systems.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 127
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 32-38 
    ISSN: 0935-6304
    Schlagwort(e): LMCS ; column bleed ; modulation ; signal enhancement ; capillary GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A Longitudinally Modulated Cryogenic System (LMCS) was evaluated for its use in detection enhancement in capillary gas chromatography. The mechanism for chromatographic re-elution for the LMCS is substantially different to other cryogenic devices. The cooled region of the capillary column in which chromatographic bands may be focused is heated by the surrounding oven temperature either by moving the trap along the column, or by moving the column out of the trap. By continually modulating the LMCS at the detector end of the capillary column, signal-to-noise ratios of routine chromatograms can be readily increased by a factor of ten, thus enhancing chromatographic detection. Base widths of peaks, which are often about 2-3 s or more can be easily reduced to 0.3 s when the LMCS is employed in the detection enhancement mode, thus offering a simple avenue to improved peak height sensitivity in capillary gas chromatography.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 128
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 47-54 
    ISSN: 0935-6304
    Schlagwort(e): multidimensional gas chromatography ; comprehensive two-dimensional gas chromatography ; GC×GC ; characterization of petroleum samples ; quantitative analyses ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A software program was developed to enable the quantification of the complex 3D-data sets as produced by GC×GC. Using this software, it was demonstrated that the detectability limit of GC×GC in our study is 18 times better than that of ‘normal’ capillary gas chromatography (CGC). This enhancement is due to the signal increase produced by the thermal modulation effect. The relative standard deviation of 0.9% as measured on a test mixture was excellent. Furthermore, a comparison was made for the group-type separation of heavy gas oils between the hyphenation of LC and GC (LC-GC) and GC×GC. Although these separations are different in nature, the agreement of the results of both methods was very good. The results of GC×GC may even be more accurate, since, different from CGC, even in the most complex chromatograms the baseline in the second dimension chromatograms is always present.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 129
    ISSN: 0935-6304
    Schlagwort(e): Bornane congeners ; toxaphene compounds ; heart-cut multidimensional gas chromatography ; enantioselectivity ; chiral GC separation ; biological samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The enantiomeric ratios of the chlorinated bornanes, 2-exo, 5,5,9,9,10, 10-heptachlorobornane (B[20030]-(022)), 2-endo,3-exo,5-endo,6-exo,8, 8,10,10-octachlorobornane (B[12012]-(202), Parlar No. 26), 2-exo,3-endo,6-endo,8,9,10,10-heptachlorobornane (B[21001]-(112)), 2,2,5,5,9,9, 10,10-octachlorobornane (B[30030]-(022), Parlar No. 38), 2-endo,3-exo,5-endo6-exo,8,8,9,10,10-nonachlorobornane (B[12012]-(212), Parlar No. 50), and 2,2,5,5,8,9,9,10,10-nonachlorobornane (B[30030]-(122), Parlar No. 62) were determined in a hake liver (Merluccius merluccius) and in two whitebeaked dolphin blubber (Lagenorynchus albirostris) samples. The analysis was performed by heart-cut multidimensional gas chromatography using an electron capture detector (ECD). Ultra 2 (5%-phenyl-95%-methylsilicone) was used as stationary phase in the first column and enantioselectivity was obtained in the second column with a phase consisting of a mixture of OV-1701 and heptakis(2,3,6-O-tert- butyldimethylsilyl)-β-cyclodextrin (10 : 1). All reference standards were also tested on the enantioselective column alone. The comparison of the two systems showed that deviations of ±0.12 from the racemic enantiomer ratio can be observed for the single column due to co-eluting impurities which are present in the reference standards. In most of the heart-cut chromatograms of the biota samples about 15 peaks could be found, showing the importance of a multidimensional separation system for an interference-free quantification by ECD. In all biological samples a significant deviation from the racemic enantiomer ratio was found for B[30030]-(022) (Parlar No. 38) and for B[30030]-(122) (Parlar No. 62). This indicates that an enantioselective disposition of the congeners occurs. In addition, considerations are presented concerning the relationship between congener structure and enantiomeric disposition.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 130
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 69-71 
    ISSN: 0935-6304
    Schlagwort(e): liquid chromatography ; chiral separations ; chiral stationary phase ; separation of enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 131
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 3-10 
    ISSN: 0935-6304
    Schlagwort(e): Co-electroosmotic capillary electrophoresis ; high performance liquid chromatography ; phenolic lignin degradation compounds ; inorganic anions ; organic modifiers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Two methods are presented for the quantitative capillary electrophoretic (CE) determination of phenolic lignin degradation compounds as well as of inorganic anions and organic acids in Kraft black liquors. Important phenolic lignin degradation compounds can be rapidly separated by co-electroosmotic CE after acidification of the liquors and subsequent extraction of the compounds with chloroform. A capillary electrophoretic separation of phenolic compounds is performed by using a phosphate/borate electrolyte system and UV detection at 214 nm. In addition, a HPLC method using a gradient with water, methanol, and acetic acid is also developed. Inorganic ions which are of importance to the pulping process can be determined by simply diluting the black liquors after sampling and subsequent analysis with a chromate electrolyte system and indirect UV detection at 185 nm. In addition, the concentration of low molecular aliphatic carboxylic acids can be determined simultaneously within the same run. By method optimization it is possible to separate the anions within one minute and, at the same time, to increase the resolution of the solutes. The electrolyte systems for the CE separations were optimized by varying the pH value and by adding organic solvents. Short separation times are obtained by adding a polycationic EOF modifier (hexadimethrine bromide) to the electrolyte which reverses the electroosmotic flow. A migration of the anionic analytes in the same direction as the electroosmotic flow is thus established.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 132
    ISSN: 0935-6304
    Schlagwort(e): high temperature capillary GC ; high temperature capillary GC-MS ; organic tracers ; OV-1701-OH ; smoke aerosols ; triglycerides ; wax esters ; triterpenyl esters ; Amazon ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A custom-made glass capillary column coated with OV-1701-OH (88% methyl, 7% cyanopropyl, 5% phenylpolysiloxane) was used to analyze smoke samples from biomass combustion of different species of plants collected in the Amazon forest. CS2 was used as solvent in order to enhance the dissolution and analysis of the heavier molecular weight components. The performance of the column was monitored during the experiments and a moderate increase in activity was observed after taking the column to high analytical temperatures (390°C). Trennzahl values typically dropped 20-30% from 1.7/m to the average of 1.35/m. In general, the performance of the custom-made column was satisfactory and comparable to the commercial high temperature columns. The high temperature high resolution GC and GC-MS analyses revealed the presence of a number of high molecular weight components reported to occur in smoke aerosols for the first time. These components consisted of series of wax esters (long chain alcohols esterified with long chain fatty acids) with up to 58 carbon numbers, aliphatic hydrocarbons, triglycerides, triterpenyl esters (e.g. α- and β-amyryl stearate). Although other types of compounds were also detected, their complete structure elucidation solely by electron impact MS was not adequate and other techniques will be required.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 133
    ISSN: 0935-6304
    Schlagwort(e): cyclodextrin derivatives ; enantiomer micropreparative GC ; thick-film wide-bore columns ; high-purity enantiomer isolation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Representative examples of preparative GC isolation of pure enantiomers in amounts ranging from 0.5 to 2 mg, with thick-film wide-bore open tubular columns coated with cyclodextrin (CD) diluted in polysiloxanes, are described. Two 25 m×0.53 mm i.d. columns, coated with 3 μm of 30% 2,6-di-O-methyl-3-O-pentyl-β-CD/OV-1701 and 2 μm of 30% 2,3-di-O-acetyl-6-O-tert- butyldimethylsilyl-β-CD/PS-086 as stationary phases, were used. Methyl 3-hydroxyhexanoate, methyl 2-methylbutanoate, δ-hexalactone, δ-octalactone, and γ-decalactone (the latter from a nature-identical mango aroma), were submitted to automated micropreparative GC. Average yields of about 30% were achieved when amounts above 20 μg/μl were injected, and an enantiomeric purity above 90% was obtained.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 134
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 113-120 
    ISSN: 0935-6304
    Schlagwort(e): Enantioselective GC of chlorinated bis(propyl) ethers ; environmental analysis ; contamination of the Elbe River ; cyclodextrin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Cyclodextrin derivatives are evaluated as chiral stationary phases for the enantiomer separation of chlorinated bis(propyl) ethers (BPE). The enantiomeric composition of the 2,3,2′,3′- and 1,3,2′,3′-isomers of tetrachlorobis(propyl) ether in the Elbe River has been quantitatively determined by enantioselective gas chromatography and coupled gas chromatography/mass spectrometry in selected-ion-monitoring mode. Significant enantiomeric discriminations are observed in selected water samples, indicating that enantioselective bio-degradation mechanisms are at least partly responsible for the overall degradation processes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 135
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 128-132 
    ISSN: 0935-6304
    Schlagwort(e): Pyrolysis ; GC/MS ; phenolic urethane resin ; thermal decomposition ; metal casting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 136
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 137-139 
    ISSN: 0935-6304
    Schlagwort(e): Pentachlorophenol ; urine ; microextraction ; SPME ; GC/MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 137
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 209-214 
    ISSN: 0935-6304
    Schlagwort(e): Dual capillary gas chromatography ; non-methane hydrocarbons (NMHCs) ; refocusing ; PLOT column ; carbon dioxide interference ; ambient air analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analytical method based on a dual capillary gas chromatographic technique combining the advantages of GasPro PLOT and a non polar narrow bore WCOT column was developed for the analysis of air samples containing C2-C9 NMHCs. A refocusing step was not required due to the fast heating rate of the sample preconcentration trap and the resolving power of the PLOT column for C2 and C3 NMHCs. Water had to be removed from the air samples to avoid plugging of the columns if the initial GC oven temperature was below ambient temperature. To dry air samples, a scrubber and a cryogenic technique were employed. The interferences caused by carbon dioxide were reduced by purging the loaded sample preconcentration trap with helium. The dual column system was compared to a method employing a refocusing device and a single narrow bore WCOT column. Both systems provided a high degree of precision. However, the dual column approach was superior to the single column system due to better resolution of low molecular weight components.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 138
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 225-233 
    ISSN: 0935-6304
    Schlagwort(e): Chiral GC ; chiral stationary phase ; cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---2,3-Di-O-pentyl-6-O-tert-butyldimethylsilyl-β-cyclodextrin has been evaluated as an enantioselective stationary phase for capillary gas chromatography. Experimental results show a good enantioselectivity towards compounds with different functional groups (haloalkanes, alcohols, esters, terpenoids, amino acid derivatives, and heterocycles). Column stability improves mixing the chiral phase with polysiloxane SE-54 (1 : 1).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 139
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 245-251 
    ISSN: 0935-6304
    Schlagwort(e): Supercritical fluid extraction (SFE) ; liquid trapping ; fat-soluble vitamins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A series of four complete factorial experiments were performed to determine the major parameters affecting the trapping efficiencies of fat-soluble vitamins after supercritical fluid extraction. The parameters varied were the collection solvent, extraction flow rate, collection temperature, restrictor temperature, and collection pressurization. The identity of the collection solvent was found to have the most profound effect. The viscosity and surface tension of the collection solvent appeared to have great significance.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 140
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 258-262 
    ISSN: 0935-6304
    Schlagwort(e): capillary gas chromatography ; splitless injection ; large sample volume ; injector design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 141
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 291-297 
    ISSN: 0935-6304
    Schlagwort(e): Gradient ; liquid chromatography ; micro-HPLC ; mixer ; electrospray mass spectrometry ; cytochrome c ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---This paper describes a new method for gradient elution at low flow rate. By adjusting the solvent composition flowing into a dynamic mixer, we can program the concentration of solvent, B, inside a dynamic mixer to form a time-resolved solvent gradient delivered to the column. The input gradient is related to the output gradient by the equation, Bin = Bout + τ × dBout/dt, in which τ is the gradient response time constant at specified flow rate, and Bin and Bout are input and output concentration of solvent B, respectively.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 142
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 309-314 
    ISSN: 0935-6304
    Schlagwort(e): Chlorophenols ; separation ; CZE ; pH ; organic modifiers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 143
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 298-302 
    ISSN: 0935-6304
    Schlagwort(e): Toxaphene ; thermal decomposition ; stationary phases ; gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Some toxaphene congeners are thermally unstable under commonly used gas chromatographic temperature conditions. The thermal stability of the 22 commercially available congeners has been studied at four different heating rates on four stationary phases Ultra 2 (5%-diphenyl-95%-dimethylpolysiloxane), a liquid crystalline phase (N,N′-bis(p-butoxy-benzylidene)-α,α′-bis-p-toluidine), Rtx-2330 (90%-biscyanopropyl-10%-phenylcyanopropyl-polysiloxane), and heptakis-(2,3,6-O-t-butyldimethylsilyl)-β-cyclodextrin (TBDMS-CD) diluted in OV-1701-OH. A substantial degradation of the congeners Parlar 39, 42, 50, 56, 58, and 62 could be observed on the cyanopropyl polysiloxane stationary phase. Furthermore, the applied temperature program and stationary phase had an influence on the signal areas. These factors are important for a quantitative analysis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 144
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 317-320 
    ISSN: 0935-6304
    Schlagwort(e): GC/MS analysis ; SIM mode ; UV stabilizers ; PET ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 145
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 323-331 
    ISSN: 0935-6304
    Schlagwort(e): Capillary zone electrophoresis ; chiral separations ; chiral crown ethers ; 18-crown-6-tetracarboxylic acid ; synthesis ; applications ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---An overview is presented of the applicability of the crown ether 18-crown-6-tetracarboxylic acid (18C6H4) as buffer additive in capillary electrophoresis (CE) for the separation of enantiomers. The chiral selector 18C6H4 is particularly useful for the separation of racemates having a primary amino function. Unfortunately, the crown ether is no longer commercially available. The synthesis and spectroscopic characterization are therefore described in detail. Moreover, a method is presented for the regeneration of the crown ether after CE application. Some new enantiomeric separations of amino acids i.e. NORLEU, ARG, GLU, m-TYR, and o-TYR are listed and the influence of the pH and temperature of the separation buffer is discussed. An intermediate in the synthetic pathway, namely 18-crown-6-tetracarboxamide, did not exhibit any enantioselectivity in CE.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 146
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 363-367 
    ISSN: 0935-6304
    Schlagwort(e): high temperature gas chromatography ; triacylglycerol ; lipids ; Jatropha multifida ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 147
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 355-362 
    ISSN: 0935-6304
    Schlagwort(e): Large volume injection ; solvent evaporation ; flooded zone ; solvent trapping ; on-column injection ; water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Using a specially treated glass capillary, evaporation of the solvent during large volume injection into a precolumn was visually investigated in order to better understand the solvent trapping process. Using an early vapor exit, the process differs from the classical description of solvent trapping. First, there is a substantial pressure drop over the solvent-coated (“flooded”) precolumn, causing evaporation to take place not only at the rear edge, but also within the flooded zone or at its front end (which may result in almost complete loss of volatile solutes). Secondly, the evaporation rate increases as the liquid enters deeper into the precolumn, eventually turning partially concurrent evaporation into a fully concurrent evaporation with massive loss of volatiles. Thirdly, the capacity of the precolumn to retain liquid is substantially higher than observed in systems without early vapor exit
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 148
    ISSN: 0935-6304
    Schlagwort(e): Headspace solid-phase microextraction (HS/SPME) ; capillary gas chromatography ; volatile wine aroma compounds ; aromatic pattern ; chemometric classification ; HS/SPME standard addition method ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Headspace solid-phase microextraction (HS/SPME) was studied and optimized for the capillary gas chromatographic (CGC) analysis of wine aroma compounds. The results were compared with those obtained using the direct sampling mode (DI/SPME) and using liquid/liquid extraction with Kaltron. The aromatic patterns obtained by HS/SPME-CGC were applied to the chemometric classification of wine varieties. The HS/SPME-CGC standard additional method is an appropriate technique for the quantitative analysis of volatile wine aroma compounds.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 149
    ISSN: 0935-6304
    Schlagwort(e): Oil ; oil spill ; GC/MS ; GC/FID ; carbon isotope ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---During January and February 1996, a significant number of tarball/patty incidents occurred along the coasts of Vancouver Island, Washington, Oregon, and California. Samples of the tarballs were collected from the affected beaches and analyzed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/flame ionization detector (GC/FID) using a tiered analytical approach developed for determining the origin of oils. Selected samples were further analyzed using a carbon isotopic technique. Also, the relative abundances of a large number of “source-specific marker” compounds, in particular alkylated series of polycyclic aromatic hydrocarbons within the same alkylation isomeric groups, were compared. Results of the analysis revealed that (1) California/Oregon samples were chemically similar and consistent with the same source. They were identified to be bunker type fuel; (2) The tarball samples collected from British Columbia and Ocean Shores, Washington were chemically similar and consistent with the same source (also bunker type fuel). They were found to be similar to but may have a source different than the California/Oregon samples; (3) The source of the tarball/patty samples was neither Alaska North Slope oil nor California Monterrey Miocene oil; (4) The spilled oil samples have been highly weathered since release, and the California samples were more heavily weathered than the British Columbia samples.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 150
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 407-410 
    ISSN: 0935-6304
    Schlagwort(e): Capillary GLC ; nitrous oxide as carrier gas ; carrier gas correlation of retention factors ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---On use of nitrous oxide as carrier gas the retention factors of the chromatographed compounds decrease linearly with increasing average column pressure. Other retention characteristics (relative retention, retention index) change linearly. This effect was demonstrated by using a capillary column coated with nonpolar polydimethylsiloxane phase SE-30. As shown for capillary GLC the linear correlation is valid for the same column:ki(G1,P1) = A ki(G2, P2) + B, where ki(G1, P1) and ki(G2,P2) are the retention factors of compound i at average column pressures P1 and P2 when using carrier gases G1 and G2, respectively; A and B are coefficients.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 151
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 414-416 
    ISSN: 0935-6304
    Schlagwort(e): chiral separation ; HPLC ; diols ; borate complexation ; cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 152
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 421-423 
    ISSN: 0935-6304
    Schlagwort(e): Capillary zone electrophoresis ; chiral separation ; cyclodextrins ; bencynonate ; econazole ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 153
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 440-444 
    ISSN: 0935-6304
    Schlagwort(e): enantiomeric separation ; β-amine alcohols ; capillary electrophoresis ; DM-β-CD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Enantiomeric separations of several β-amino alcohol drugs, i.e., phenylephrine, epinephrine, norepinephrine, synephrine, and chlorprenaline were performed by capillary electrophoresis using DM-β-CD as a chiral selector. Five test solutes were baseline resolved in six minutes. The effects of DM-β-CD concentration, pH value, ionic strength of the buffer, and the type of β-CDs on resolution were investigated. The results indicated that DM-β-CD is suitable for enantiomeric separation of β-amino alcohols containing a phenyl group on the chiral atom. Enantiorecognition mechanisms for test solutes are also discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 154
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 457-463 
    ISSN: 0935-6304
    Schlagwort(e): Supercritical Fluid Extraction (SFE) ; ultrasonication extraction ; gas chromatography ; derivatization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Supercritical fluid extraction (SFE) of alkyl alkylphosphonofluoridates and dialkyl alkylphosphonates from painted plates was investigated. It was found that SFE recoveries compared favorably with conventional solvent sonication results. Stability studies of the samples were carried out over a period of two months. This investigation showed that the concentration of phosphonofluoridates decreased over a long period.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 155
    ISSN: 0935-6304
    Schlagwort(e): Cold on-column injector ; high temperature high resolution gas chromatography ; rotenoids ; PS-090 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A short glass capillary column coated with PS-090 (20% phenyl-80% methylpolysiloxane, of 10 m × 0.30 mm i.d.; with 0.1 μm film thickness) was used to analyze samples from Tephrosia candida; eighteen rotenoids were separated and identified without derivatization by HT-HRGC and HT-HRGC-MS. The mass spectra show the typical fragmentation pattern for rotenoids, with the base peaks either at M+, or originating from RDA (Retro Diels-Alder) rearrangements. HT-HRGC and HT-HRGC-MS were shown to be extremely valuable and neglected techniques for structural studies as well as the routine analysis of rotenoids in crude extracts. Possible applications to other classes of aromatic natural products, e.g. flavonoids, are envisaged.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 156
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 540-544 
    ISSN: 0935-6304
    Schlagwort(e): capillary electrophoresis ; thermionic detector ; nitrogen-selective detection ; eluent-jet interface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The on-line coupling of capillary electrophoresis (CE) with a thermionic detector (TID) originally developed for gas chromatography (GC) is reported for the first time. An eluent-jet interface previously used to combine micro-liquid chromatography and mass spectrometry can now be used to couple CE and TID. Preliminary results demonstrate the possibility of performing direct nitrogen-selective detection, even for less volatile compounds. Detection limits of 4-12 pg N/s were obtained for the four tested compounds piperidine, dimethylformamide, tetra-n-butylammonium hydroxide, and nicotinic acid. Optimization of both the TID and the eluent-jet interface can be performed independently; optimum TID parameters agree rather closely with the detector specifications under GC conditions. The nitrogen-selective TID proved to be linear over more than three orders of magnitude with acceptable repeatability. The on-line coupling of CE and TID may well become an interesting approach for the rapid and direct analysis of ionic and high-molecular-mass N-containing compounds.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 157
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 545-548 
    ISSN: 0935-6304
    Schlagwort(e): Capillary electrochromatography (CEC) ; fish oil ; triglycerides ; free fatty acids (FFAs) ; fatty acid methyl esters (FAMEs) ; fatty acid phenacyl esters (FAPEs) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---Capillary ElectroChromatography (CEC) on a fused silica capillary column (40 cm L × 100 μm i.d.) packed with 3 μm octadecylsilica (ODS) was evaluated for the analysis of the triglycerides and their fatty acids in fish oils, and more especially in the oil of Moroccan Sardinia pilchardus. The very high complexity of the lipids in fish oil is well illustrated by CEC with a nonaqueous mobile phase consisting of acetonitrile/isopropanol/n-hexane in the ratio 57/38/5 to which 50 mM ammonium acetate has been added. In order to unravel the complexity, the oil was hydrolyzed and the free fatty acids (FFAs), the methyl esters (FAMEs), and the phenacyl esters (FAPEs) were analyzed by CEC on the same column used for the analysis of the triglycerides. Isocratic elution was achieved with the mobile phase acetonitrile/50 mM MES pH 6 in ratio 9/1. The migration characteristics of FFAs, FAMEs, and FAPEs are compared. The analysis of FAPE derivatives has the advantage that quantification applying UV detection is possible and moreover that the number of double bonds in the fatty acid chains can be elucidated by measuring the UV abundance ratio 240/210 nm.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 158
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 450-456 
    ISSN: 0935-6304
    Schlagwort(e): Drying cartridge ; gas chromatography ; solid-phase extraction ; microcontaminants ; water samples ; on-line SPE-GC ; mass spectrometric detection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A drying cartridge was used and optimized for the in-line elimination of water from the desorption eluent in on-line solid phase extraction-gas chromatography (SPE-GC). The cartridge is essentially a small stainless-steel precolumn packed with a drying agent which can be regenerated by simultaneous heating and purging with a moisture-free gas. The drying cartridge was mounted on an additional valve instead of between the SPE-GC transfer valve and the on-column injector to enable regeneration of the cartridge during the GC run and, thus, to increase sample throughput. Three drying agents were tested, viz. sodium sulfate, silica, and molecular sieves. Although molecular sieves have the highest capacity, silica was preferred because of practical considerations. Large-volume injections were performed through the in-line drying cartridge using a mixture of 23 microcontaminants ranging widely in polarity and volatility. Four solvents were tested. With pentane and hexane, the more polar analytes were retained by the drying cartridge. Ethyl acetate and methyl acetate gave much better (and closely similar) recoveries for all analytes. Because water elimination on the silica cartridge proved to be less critical than with ethyl acetate, this solvent was finally selected. The entire SPE-drying cartridge-GC set-up was combined with mass spectrometric (MS) detection for the determination of a mixture of micropollutants in real-life water samples. With 10-ml tap water samples spiked at the 0.5 μg/l level, for the majority of the test compounds the analyte recoveries generally were 60-106%, and (full-scan) detection limits typically were 0.01-0.03 μg/l. Some very polar analytes such as, e.g. dimethoate, were (partially) sorbed onto the silica packing of the drying cartridge.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 159
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 464-470 
    ISSN: 0935-6304
    Schlagwort(e): liquid chromatography ; chiral separation ; chiral recognition mechanism ; chiral stationary phase ; separation of enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---A chiral recognition mechanism which can rationalize the resolution of N-(3,5-dinitrobenzoyl)-α-amino amides on chiral stationary phases (CSPs) obtained from N-(3,5-dinitrobenzoyl)leucine amide derivatives has been proposed on the basis of the chromatographic resolution behavior of various N-(3,5-dinitrobenzoyl)-α-amino acid derivatives and N-(various benzoyl)leucine N-propyl amides. The proposed chiral recognition mechanism utilizes two hydrogen bonding interactions between the CSP and the analyte and a π-π donor-acceptor interaction between the N-(3,5-dinitrobenzoyl) groups of the CSP and the analyte. From the chiral recognition mechanism proposed, it has been concluded that the resolution of π-acidic N-(3,5-dinitrobenzoyl)-α-amino acid derivatives on π-acidic CSPs derived from N-(3,5-dinitrobenzoyl)leucine amide delivatives is not unusual, but is merely the extension of the resolution of the π-basic racemates on π-acidic CSPs. However, the chromatographic behavior of the resolution of N-(3,5-dinitrobenzoyl)phenylglycine derivatives on CSPs derived from N-(3,5-dinitrobenzoyl)leucine amide derivatives is different from that of the resolution of other N-(3,5-dinitrobenzoyl)-α-amino acid derivatives. To rationalize this exceptional behavior, a second chiral recognition mechanism which utilizes two hydrogen bonding interactions (which are different from those of the first chiral recognition mechanism) between the CSP and the analytes and a π-π donor-acceptor interaction between the N-(3,5-dinitrobenzoyl) group of the CSP and the phenyl group of the analytes has been proposed to compete with the first chiral recognition mechanism. In this instance, it has been proposed that the separation factors and the elution orders of the resolution of N-(3,5-dinitrobenzoyl)phenylglycine derivatives are dependent on the balance of the two competing chiral recognition mechanisms.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 160
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 477-479 
    ISSN: 0935-6304
    Schlagwort(e): Silica rod column ; micro-HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 161
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 47-53 
    ISSN: 1075-4261
    Schlagwort(e): infrared spectroscopy of human tissue ; basal, parabasal, and superficial layers of cervical squamous epithelium ; cell maturation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Infrared spectral results for the different epithelial layers of human cervical squamous tissue are reported. The layers, representing different cellular maturation stages, exhibit quite different spectral patterns. Thus, infrared spectroscopy presents a powerful tool to monitor cell maturation and differentiation. Furthermore, a detailed understanding of the spectra of the individual layers of tissue permit a proper interpretation of the state of health of cells exfoliated from such tissue. Part II of this series describes the use of the spectral information presented here to interpret the infrared spectra of exfoliated cells. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 47-53, 1998
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 162
    ISSN: 1075-4261
    Schlagwort(e): infrared spectroscopy of human tissue ; squamous epithelium ; exfoliated cells ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: A comparison of infrared absorption spectra obtained from the different layers of squamous epithelium from the human cervix, and infrared spectra obtained from exfoliated cervical cells, is presented. Infrared spectroscopy has been shown (in part I of this series) to be a sensitive tool to monitor maturation and differentiation of human cervical cells; therefore, this spectroscopic technique provides new insights into the composition and state of health of exfoliated cells. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 55-59, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 163
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 61-71 
    ISSN: 1075-4261
    Schlagwort(e): L-tyrosine ; polarized Raman spectra ; Raman tensor ; ab initio MO calculation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: Polarized Raman scattering measurements have been made of a single crystal of L-tyrosine by the use of a Raman microscope with the 488.0-nm exciting beam from an argon ion laser. The L-tyrosine crystal belongs to the space group P212121 (orthorhombic), and Raman scattering intensities corresponding to the aa, bb, cc, ab and ac components of the crystal Raman tensor have been determined for each prominent Raman band. A similar set of measurements has been made of L-tyrosine-d4, in which four hydrogen atoms on the benzene ring are replaced by deuterium atoms. The effects of NH3 → ND3 and OH → OD on the Raman spectrum have also been examined. In addition, depolarization ratios of some bands of L-tyrosine in aqueous solutions of pH 13 and pH 1 were examined. For comparison with these experimental results, on the other hand, ab initio molecular orbital calculations have been made of the normal modes of vibration and their associated polarizability oscillations of the L-tyrosine molecule. On the basis of these experimental data and by referring to the results of the calculations, discussions have been presented on the Raman tensors associated to some Raman bands, including those at 829 cm-1 (benzene ring breathing), 642 cm-1 (benzene ring deformation), and 432 cm-1 (Cα-Cβ-Cγ bending). © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 61-71, 1998
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 164
    ISSN: 1075-4261
    Schlagwort(e): FTIR microspectroscopy ; cervical cancer ; leukocytes ; lymphocytes ; erythrocytes ; semen ; mucins ; fibroblasts ; thrombocytes ; bacteria ; nylon ; Candida albicans ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Physik
    Notizen: FTIR microscopy was applied to the analysis of cell types and other variables present in Pap smears to ascertain the limitations of infrared spectroscopy in the diagnosis of cervical cancer and dysplasia. It was found that leukocytes, and in particular lymphocytes, have spectral features in the phophodiester region (1300-900 cm-1) suggestive of what has previously been described as changes indicative of malignancy. Endocervical cells and fibroblasts have similar spectral features to HeLa cells and consequently could also confound diagnosis. The use of ethanol as a fixative and dehydrating agent results in retention of glycogen in cervical cell types and thus minimizes spectral changes in the glycogen region due to sampling technique. Spectra of seminal fluids exhibit strong bands in the phosphodiester/carbohydrate region; however, sperm contamination should be easily detectable by the presence of a distinctive doublet at 981/968 cm-1. Erythrocyte spectra exhibit a reduction in glycogen band intensity, but can be discerned by a relatively low-intensity νs $PO^{-}_{2}$ band. Endocervical mucin spectra exhibit a reduction in glycogen bands and a very pronounced νs $PO^{-}_{2}$ band, which is similar in intensity to the corresponding band in HeLa cells. Thrombocytes have strong bands in the phosphodiester region, but thrombocytes can be discerned from other cell types by the presence of two small broad bands at 980 and 935 cm-1. Candida albicans is characterized by strong bands in the polysaccharide region which could potentially obscure diagnostic bands if C. albicans is present in large numbers. Spectra of bacteria common to the female genital tract, in general, also have strong absorptions in the polysaccharide region; however, bacterial contamination is usually minimal and would not be expected to obscure cervical cell spectra. Nylon threads and bristles from cervical sampling implements produce characteristic IR profiles which allow for easy identification. Given the number of potential confounding variables associated with cervical cytology, a multivariate statistical or neural network analysis would appear to be necessary before the implementation of FTIR technology in clinical laboratories. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 75-91, 1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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