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  • 1
    Electronic Resource
    Electronic Resource
    Identification and Quantification of Monobromopolychlorobiphenyls in Baltic Ringed Seal and a Technical PCB (Clophen A50) (1995)
    s.l. : American Chemical Society
    Environmental science & technology 29 (1995), S. 2801-2805 
    Details
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/es00011a014
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Polychlorinated biphenyls and polychlorinated naphthalenes in Swedish sediment and biota: levels, patterns, and time trends (1993)
    s.l. : American Chemical Society
    Environmental science & technology 27 (1993), S. 1364-1374 
    Details
    ISSN: 1520-5851
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/es00044a011
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of the rotational energy barriers of atropisomeric polychlorinated biphenyls (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 219-223 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The rotational energy barriers were determined for twelve of the nineteen environmentally stable atropisomeric polychlorinated biphenyls (PCBs), viz. PCB 84, 131, 132, 135, 136, 144, 149, 174, 175, 176, 183, and 196, by thermal racemization of enantiomerically pure PCBs. The rate of racemization was primarily determined using off-line gas chromatography (GC) or high-performance liquid chromatography (HPLC), with permethylated cyclodextrin (PMCD) as the chiral selector. GC was used for PCB 84, 132, 136, 149, 174, and 176, while PCB 131, 175, and 196 were analyzed using HPLC. The remaining PCBs, i.e. PCB 144 and 183, were separated by HPLC using a Chiralpak OP(+) polymethacrylate column. Gibbs free energy of activation (Δ
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051327
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Ultraviolet absorption spectra of all 209 polychlorinated biphenyls evaluated by principal component analysis (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 1088-1092 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ultraviolet absorption spectra of all 209 polychlorinated biphenyls (PCBs) were recorded in the range 200–300 nm and displayed two important absorption maxima, viz., the main-band, λmax 200–225 nm, and the κ-band, λmax 245–265 nm. By utilising principal component analysis, substitution related spectral characteristics of the PCBs, underlying the main patterns of the spectra, were examined. Captured in the multivariate evaluation were e.g., the importance of chlorine atoms in ortho positions, determining the intensity and existence of the κ-band, chlorine substitution in para-para position, and the total number of chlorine atoms. The measured UV-spectra of all 209 polychlorinated biphenyls provide important physico-chemical descriptors for use in future quantitative structure-activity and structure-property relationship (QSAR/QSPR) studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050310
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of the gas chromatographic elution sequences of the (+)- and (-)-enantiomers of stable atropisomeric PCBs on Chirasil-dex (1996)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 373-376 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Stable atropisomeric polychlorinated biphenyls (PCBs) ; Elution sequences ; Cyclodextrin derivatives ; Chirasil-Dex ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pure enantiomers of chiral (atropisomeric) polychlorinated biphenyls (PCBs) obtained by high-performance liquid chromatography were used to establish the gas chromatographic elution sequences of the (+)- and (-)-enantiomers of six PCB atropisomers on Chirasil-Dex. The elution order was found to be (-/+) for PCBs 84, 132, 136, and 176 and (+/-) for PCBs 135 and 174. The retention characteristics of all 19 tri- and tetra-ortho atropisomeric PCBs were also investigated. Nine of the atropisomers could be separated using this chiral selector. PCBs 95, 132, and 149 were completely resovled and PCBs 84, 91, 135, 136, 174, and 176 were partially separated (R = 0.7-0.9). All of the separated congeners are 2,3,6-substituted in at least one ring, and conversely - none of the congeners that lacks 2,3,6-substitution could be separated. Thus, chiral recognition and enantiomer separation seems to be strongly governed by 2,3,6-substitution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240190703
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    A Robust Thermal Modulator for Comprehensive Two-Dimensional Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 3-10 
    Details
    ISSN: 0935-6304
    Keywords: Multidimensional Gas Chromatography ; orthogonal separations ; GC×GC ; comprehensive two-dimensional chromatography ; characterization of gasoline ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In comprehensive two-dimensional gas chromatography (GC×GC), two capillary columns are connected in series through an interface known as a “thermal modulator”. This device transforms effluent from the first capillary column into a series of sharp injection-like chemical pulses suitable for high-speed chromatography on the second column. Dramatic increases in the resolving power, sensitivity, and speed of the gas chromatograph result. This paper describes the development of a robust and reliable thermal modulator for GC×GC.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Comparison of Thermal Sweeper and Cryogenic Modulator Technology for Comprehensive Gas Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 253-258 
    Details
    ISSN: 0935-6304
    Keywords: Comprehensive gas chromatography ; cryogenic modulation ; semi-volatile aromatics ; thermal sweeper ; peak widths ; peak asymmetries ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The two current technologies for achieving comprehensive gas chromatography (GC×GC) - the thermal sweeper and the cryogenic modulator - are compared in an interlaboratory study using a multicomponent semi-volatile aromatic compound sample. The same column set (phases, film thickness, dimensions of columns) and conditions of oven temperature program were used. Carrier gas flow settings however were different for the data reported here. The thermal sweeper has a longer overall length due to the extra ca. 30 cm length of narrow bore tubing used for the modulator/accumulator section. Data reveal that the two methods behave in an analogous manner in respect of delivering GC×GC results, with key peak parameters of peak widths and symmetry measures showing good correlation. Retention time dissimilarity on the first dimension columns in the two systems arises from different flow rates used, however the second column retention is similar, and this is due to the resulting different elution temperatures that peaks elute on the first dimension in each system. Overall, the two approaches to GC×GC appear to produce equivalent results within the scope of the application studied. Each system does have its experimental limitations; the thermal sweeper has what may be called a ‘thick film effect’, where at high temperature it can be difficult to sufficiently trap the migrating bands in the accumulator column, and the pulsing of solutes in the cryogenic system may suffer from a ‘thick wall effect’ if a column with too thick a wall dimension is used at low oven temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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