Volatile identification

The sophisticated equipment required for volatile identification has long confined the topic of herbivore-induced volatiles to the laboratory, but extrafloral nectaries have traditionally been studied in the field. Moreover, the work on extrafloral nectaries has mainly addressed wild plant species within their natural habitat, whereas the study of plant volatiles has long focussed on agricultural crops. As a result, we have a relative wealth of held evidence for the defensive function of extrafloral nectaries. 

El-Sharkawy, I., Manriquez, D., Flores, F.B., Regad, F, Bouzayen, M., Latche, A. and Pech, J.C. (2005) Functional characterization of a melon alcohol acyl-transferase gene family involved in the biosynthesis of ester volatiles. Identification of the crucial role of a threonine residue for enzyme activity. Plant Mol. Biol, 59, 345-62. 

As a result of their limited volatility, identification of organic additives in polymers by using TG-MS is considerably more difficult than that of residual volatiles (such as rest monomers and solvents). Actually, TG-MS is an ideal technique for identifying residual volatiles in polymers. The detection of such volatiles (and of other impurities) can often yield clues as to manufacturing processes. 

A water-soluble mixture may be in the form of a mixture of water-soluble solids or in the form of a liquid. The liquid mixtimes are frequently aqueous solutions. The prelirninary examination of a liquid mixture (see 1) will indicate whether a volatile solvent (i.e., removable on a boiling water bath) is present. If a volatile solvent is present, distil 20 g. of the mixtime from a water bath until no more hquid passes over set aside the volatile solvent for identification. Dissolve the residue (B) in water as detailed below for a mixture of solids. 

The Soviet scientists have performed experiments aimed at chemical identification, and have attempted to show that the 0.3-s activity is more volatile than that of the relatively nonvolatile actinide trichlorides. This experiment does not fulfill the test of chemically separating the new element from all others, but it provides important evidence for evaluation. 

Gases and volatile materials can be swept into the center of an argon plasma flame, where they are fragmented into ions of their constituent elements. The m/z values of ions give important information for identification of the elemental composition of a sample, and precise measurement of ion abundances is used to provide accurate isotope ratios. 

B. D. Mookherjee and R. Patel, "Isolation and Identification of Volatile Constituents of Tiacture of Ambergris," paper presented at the FTIth International Congress of Essential Oils, Oct. 7—11, 1977, Ityoto, Japan. 

FIG. 25-43 Solids identification. Abbreviations TS, total solids SS, suspended solid D, dissolved V, volatile. 

Nepeta (Lamiaceae) is a genus of perennial or annual herbs found in Asia, Europe and North Africa. About 250 species of Nepeta are reported of which, 67 species are present in Iran. Some species of this genus are important medicinal plants and their extracts have been used for medicinal purposes. Aerial parts of Nepeta sintenisii Bornm. was subjected to hydrodistillation and the chemical composition of isolated essential oil has been analyzed by GC/MS method for first time. Identification of components of the volatile oil was based on retention indices relative to n-alkanes and computer matching with the Wiley275.L library, as well as by comparison of the fragmentation patterns of the mass spectra with those reported in the literature. 

A multidimensional system using capillary SEC-GC-MS was used for the rapid identification of various polymer additives, including antioxidants, plasticizers, lubricants, flame retardants, waxes and UV stabilizers (12). This technique could be used for additives having broad functionalities and wide volatility ranges. The determination of the additives in polymers was carried out without performing any extensive manual sample pretreatment. In the first step, microcolumn SEC excludes the polymer matrix from the smaller-molecular-size additives. There is a minimal introduction of the polymer into the capillary GC column. Optimization of the pore sizes of the SEC packings was used to enhance the resolution between the polymer and its additives, and smaller pore sizes could be used to exclude more of the polymer... 

These are semisolid or solid substances formed in nature from crude oils after the volatile components have evaporated and the remainder has undergone oxidation and polymerization. They are also referred to as bitumens, waxes, and pitch. These materials are believed to consist of mixtures of complex organic molecules of high molecular weight. As with crude oils, which contain thousands of different chemical compounds, an exact chemical analysis for identification and composition is impractical to perform on the solid deposits of petroleum. 

The preparation and identification of four types of S03-sulfonated products of linear and branched 1-alkenes (C5-C14) are described by Boyer [121]. 13C-and, to a lesser extent, -NMR spectra were used to ascertain the structures of 2-alkenesulfonic acids, p-sultones (as 2-methoxyalkanesulfonic acids), y- and 5-sultones. The mass spectra of some methyl 2-methoxyalkanesulfonates and 4-alkyl-5-sultones were also studied. Sufficiently volatile mixtures were separated by GLC after methylation of the sulfonic groups. 

The increasing sophistication and detection capabihties of instruments (tike GC-MS, LC-MS, etc.) used in the analysis of contaminants in a factory atmosphere are enabhng the identification of chemical compounds hitherto not suspected of being present. The range of volatile species so far identified during vulcanization is shown in Eigure 37.6 [49]. 

Ong CN, Koh D, Foo SC, et al. 1993. Volatile organic solvents in correction fluids identification and potential hazards. Bull Environ Contam Toxicol 50 787-793. 

Ramsey JD, Flanagan RJ. 1982. Detection and identification of volatile organic compounds in blood by headspace gas chromatography as an aide to the diagnosis of solvent abuse. J Chromatogr 240 423-444. 

The identification of volatile compounds of both Mo and W in gases from a municipal landfill (Feldmann and Cullen 1997) illustrated unusual transformation products. Although these compounds were tentatively identified as Mn2(CO)jo and W(CO)g, neither the mechanism of their formation nor their potential health hazards has been resolved. 

After the identification of the suitable compound bands, silica gel is scraped off the plates, placed in short glass columns, Pasteur pipettes, or sintered filter funnels, and fractions are recovered with such volatile solvents as ethyl acetate or dichloromethane. 

Bicchi, D., Belliardo, F., and Frattini, C. (1983). Identification of the volatile components of some Piedmontese Italy honeys. /. Apicult. Res. 22,130-136. 

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