Volatiles, indigenous

PMMA. Wolf and Grayson (16) used this technique to monitor the evolution of indigenous volatile compounds in composite materials and to study the mechanical degradation of PS (JO). 

Many analytical methods for characterizing indigenous volatile compounds are described in the literature. Gas chromatography has been used to analyze polymers for plasticizer content (30), residual monomer 1,31), and nonpolymerizing impurities (10,11,32), Grayson and coworkers (10,11) use a desorption technique which is a variation of the systems described by Levy et al. (33) and Ligon et al. (34). 

A precision abrasion apparatus (Figure 10) which will be used to determine quantitatively the distribution of indigenous volatile compounds in polymeric materials is under construction. A precisely known volume of the sample will be abraded by a motor-driven tool and a motor-driven three-degree-of-freedom sample stage. Continuous ion monitoring of the evolved compounds will permit quantitative analysis of their distribution in the polymer sample. 

It is apparent from these studies that stress MS of polymeric and composite materials is a practical method to analyze for compounds trapped within the matrix. The technique is not meant to replace existing thermal desoprtion GC/MS techniques but is complementary to them. The primary advantages of stress MS as a way to characterize indigenous volatile compounds are that labile compounds can be detected and that information on the distribution of the compounds in the sample can be obtained. However, this method is not as sensitive as conventional methods in which the evolved volatile compounds are concentrated prior to analysis. Furthermore, it is necessary to interpret the mass spectrum of the mixture of compounds. Nevertheless, the diflBculties associated with the determination of impurities of unreacted compounds in an intractable polymeric matrix warrants the continued development of stress MS. 

Grayson et al. (10) investigated untreated, vacuum-baked at 120°C, and fractionally reprecipitated PS. They analyzed the various samples for indigenous volatile content by vaporization-gas chromatography/mass spectrometry (33,36,37) and found that fractional reprecipitation was the only effective method to remove the volatile fraction from PS. Further, stress MS experiments with PS samples prepared from the fractionally reprecipitated polymer evolved only a trace of styrene monomer. 

Deeper contamination may be remedied with bioventing, where air is injected through some wells, and extracted through others to both strip volatiles and provide oxygen to indigenous organisms. Fertilizer nutrients may also be added. This is usually only a viable option with lighter refined products. 

Amyris Oil. Obtained by steam distillation of the wood of y m hakamijera L., the so-called West Indian sandalwood which is indigenous to northern South America, Central America, and the West Indies, amyris oil [8015-65-4] is a pale yellow to brownish yellow viscous oil with a slightly oily-sweet and occasionally peppery balsamic woody note. It finds use as a blender and fixative for soap fragrances. The volatile constituents, which are primarily hydrocarbon and oxygenated sesquiterpenes, are shown in Table 22 and Figure 5 (63). 

Biological. 1,1-Dichloroethane showed significant degradation with gradual adaptation in a static-culture flask-screening test (settled domestic wastewater inoculum) conducted at 25 °C. At concentrations of 5 and 10 mg/L, percent losses after 4 wk of incubation were 91 and 83, respectively. At a substrate concentration of 5 mg/L, 19% was lost due to volatilization after 10 d (Tabak et ah, 1981). Under anoxic conditions, indigenous microbes in uncontaminated sediments produced vinyl chloride (Barrio-Lage et al, 1986). 

Biovault is a commercially available, nonproprietary, ex situ treatment for soil and sediment contaminated with chlorinated and nonchlorinated volatile organic compounds (CVOCs and VOCs). The basic biovault process is to promote the degradation of the existing soil contaminants in consolidated piles by stimulation of the indigenous (or augmented) microbial population. The process typically includes low-intensity aeration, moisture control, and supplementation with nutrients. 

The main factors influencing CP remediation include temperature, the properties of the environmental matrix, the toxicity of CPs or other compounds, and the composition of indigenous or added microbial cultures (Crawford Mohn, 1985). Unlike many other xenobiotics, CPs undergo insignificant volatilization (Valo Salkinoja-Salonen, 1986 Lamar et al., 1990b Mueller et al., 1991a). The temperature, the contaminant bioavailability, the possible process amendments and the effects of additional contaminants are discussed below. 

Eugenol occurs in essential oils and is a major constituent of carnation, cinnamon, and clove oils. The substance is primarily is obtained from the clove oil isolated from trees indigenous to the Molluca Islands, and which are also cultivated in other parts of Indonesia, Zanzibar, Madagascar, and Ceylon. Clove is rich in volatile oil (16-19% by weight), which can be obtained by distillation. 

This ancient component has been observed in the highland soils, as predicted67, 68. Volatile elements do not give a clear picture, as the correction for the indigenous contribution to the ancient component is difficult to estimate. We shall therefore restrict the discussion to the siderophile elements, because the correction is likely to be quite small in this case. The old breccias of Apollo 14 had a meteoritic contribution with an Ir/Au ratio of about 1.5, as compared to about 3.5 in the mare soil samples. Moreover, the abundance pattern of the other indicator elements does not match that of any known... 

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