Gas chromatographic traces

H. Hachtenberg, Industrial Gas Chromatographic Trace Analysis, Heyden and Son Ltd., London, 1973. 

Figure 2. Gas chromatographic traces of hold eagle extract, and TCDD and hexa-CDD amended extract before and after irradiation by UV light...

Fig. 4 Gas chromatographic traces of extracts from females of the pale brown chafer Phyl-lopertha diversa monitored by a conventional detector, flame-ionization detector (FID), and a biosensor, electroantennographic detector (EAD), using a male antenna as the sensing element. Although the peak of the sex pheromone (arrow) is hardly seen in the FID trace, its pheromonal activity was initially indicated by the strong EAD peak. Structural elucidation, followed by synthesis and behavioral studies lead to the identification of an unusual sex pheromone, l,3-dimethyl-2,4-(lff,3ff)-quinazolinedione [124]. It is unlikely that this minor compound would be fished out by a bioassay-oriented isolation procedure...

Gas chromatographic traces from a defined mixed culture system for water denitrification, showing efficient interspecies H2 transfer... 

Figure 9.6 Gas chromatographic traces from a defined mixed culture system for water denitrification, showing efficient interspecies H2 transfer. I - Denitrifying bacterium. 2 -F j producer. 3 - H2 producer + denitrifying bacterium.

Visual inspection of key naturally occurring peaks from a gas chromatograph trace in relation to the usual baseline variation, reflecting the sensitivity or the... 

Figure 27-6 Gas chromatographic trace from elemental analyzer, showing substantially complete separation of combustion products. The area of each peak (when they are not off scale) is proportional to the mass of each product- [From Pella. -Elemental Organic Analysis. 2. Slate of the Art "Am. Lab August 1990, p. 28.)...

Tsuchiya, M., Yasuda, Y., Kamada, H. Gas chromatographic trace analysis of permanent gases by using radioactive ionisation detector. Bunseki Kagaku 14, 155 ( 1965). — Gas chromatog. Abstr. 1966, 469. 

Hachenberg, H., Gutberlet, J. Gas chromatographic trace analysis of gases. Brenn-stoff-Chem. 49, 242, 279 (1968). - Anal. Abstr. 18, 643 (1970). 

J. Hinshaw, Capillary inlet systems for gas chromatographic trace analysis, J. Chromatogr. Sci., 26 142-145 (1988). 

Since a large number of polycarbonates possessing the desired structural features can be prepared from a variety of diols, it is useful to develop simple methods to predict their behavior as resist materials. To this effect, we have devised spectroscopic methods to follow the degradation of the polycarbonates under a variety of thermolysis or acidolysis conditions. For example, the thermolysis of the solid polymers can be followed conveniently by gas-chromato-graphy-mass spectrometry. The thermolysis is a very clean reaction which proceeds as shown in Scheme III without side-product formation. Figure 4 shows the gas chromatographic trace obtained when polymer II is subjected to thermolysis near 250 the products analyzed by the mass spectrometer have the expected structures as shown in Figure 4. 

Figure 1. Gas chromatograph trace using F I.D. of a standard mixture of 20 ng each metal chelates.

D. Tanzer, K. G. Heumann, Gas chromatographic trace-level determination of volatile organic sulfides and selenides and of methyl iodide in Atlantic surface water. Intern. J. Environ. Anal. Chem., 48 (1992), 17-31. 

Figure 9. Gas chromatographic traces of the pyrolysis products from recent (upper trace) and buried (lower trace) oak wood samples. Circles represent polysaccharide pyrolysis products, inverted triangles represent guaiacyl lignin pyrolysis products, and upright triangles represent syringyl pyrolysis products. (Reprinted with permission from ref. 44. Copyright 1987 Elsevier Science...

Figure 6. Concentrations of total extractable aliphatic hydrocarbons in sediment cores from Lake Washington in urban Seattle and Lake Quinault in rural Washington. Gas chromatographic traces illustrate hydrocarbon distributions in three of these core samples. Carbon numbers of/i-alkanes are indicated on the traces UCM represents the unresolved complex mixture of hydrocarbons underlying the individual aliphatic hydrocarbon peaks. Most of the increase in Lake Washington hydrocarbon concentrations since ca. 1900 is due to the large addition of petroleum residues, indicated by the UCM, to a low background of land plant n-alkanes, typified by the Lake Quinalt hydrocarbon contents. Core sediment ages shown are from - "Pb dating. Adapted from Wakeham (1976).

Analyses were performed on a number of resistant and susceptible plants in order to determine whether the chemical composition was constant within each plant line. While it was found that the chemical profile of the resistant plants was fairly constant, the exudate from susceptible plants exhibited variability. Furthermore, on close examination of the gas chromatographic trace of the exudate from susceptible plants, it was determined that in addition to the four previously identified compounds, there were a number of other significant peaks, which were unidentified. In addition, as all the peaks eluted close together, it was possible that the apparent variability was due to unresolved peaks (5. 6). 

Examples of gas chromatographic isotope separation are shown in O Figs. 51.10 and O 51.11. The gas chromatographic trace of a separation of a mixture of protio and deutero-acetylenes is shown in Fig. 51.10 (Phillips and Van Hook 1967). The separation is interesting, all known preparations of these acetylenes lead to a disproportionated mixture of C2H2, C2HD,... 

FIGURE 7.11 Reconstructed gas chromatographic trace for a lavender essential oil (a) and the 2D separation space for the 2D gas chromatography analysis of the same sample (b). The minor component Z overlaps completely from the major component Y in the D. M, monoterpene hydrocarbons S, sesquiterpene hydrocarbons. (From Shellie, R. et al, J. Chromatogr. A, 970, 225, 2002. With permission.)... 

Vitenberg, A.G. Ioffe, B.V. and Borisov, V.N. Application of phase equilibria to gas chromatographic trace analysis. Chromatographia 1974, 7, 610-619. 

The references contain detailed information on sample size, collection sites and gas chromatographic traces (see Fig. 12 for gas chromatographic traces for the two populations of Dendrobates bombetes). Certain data in the footnotes is from Myers and Daly (unpublished). Six populations of Dendrobates femoralis, a widespread Amazonian species have been analyzed and an alkaloid (181B, trace) was tentatively identified... 

Peak areas in gas-chromatographic traces are measured in several ways. Most simply peak heights in arbitrary units (e.g. mm) can be used or the areas estimated (for Gaussian peaks) from the product of peak height and peak width at half-height. These methods are usually sufficiently accurate even in cases where for some reason the baseline alters during elution of the peak and requires to be estimated. 

Fig. 5.10 Part of a reconstructed computer-drawn chromatogram (lower trace) from a maximizing ion treatment of repetitively scanned data acquired from a sample with the gas-chromatographic trace shown (top). 

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