Elemental composition of organic

Changes in elemental composition of organic matter during coalification... 

Table I. Average Element Composition of Organic Matter in Mahogany Zone Composites...

This mode of deposition over a wide area explains the lateral uniformity observed in element composition of organic matter in Mahogany zone oil shale (16), and the similarity in properties of the oil-shale organic matter over the entire deposit. The paucity of macrofossils in the oil shale, limited largely to an occasional gar scale and the like, illustrates the power of the lake s lower layer to digest organic matter. 

Table 3.4. Exact masses and elemental compositions of organic phosphorus molecules observed in the ...

The analysis of the classification of plant materials in the Methode de nomenclature chimique, presented at the beginning of chapter 14, creates an important link between parts II and III of this book. This analysis first shows the ambition of Lavoisier and his collaborators to extend classification according to composition to plant substances, and, second, their failure in terms of collective acceptance. The next section of the chapter continues this analysis of their failure inasmuch as it points out the theoretical limits of the Lavoisierian analytical program. As Lavoisier s theory of the elemental composition of organic substances did not include the assumption of stoichiometric organic compounds, it was unsuitable as a working tool for the envisioned analytical mode of identification and classification of organic compounds. 

Calcium chloride is found in the marine environment. The elemental composition of seawater is 400 ppm calcium, 18,900 ppm chlorine, and many organisms and aquatic species are tolerant of these concentrations. Toxicity arises either from the invasion of freshwater in otherwise saltwater environments or possible toxic doses of calcium chloride from spills, surface mnoff, or underground percolation into typically freshwater streams or aquifers. Various agencies have guidelines for calcium and chloride in potable water (41). The European Economic Community (EEC) is the only agency to have a minimum specification for calcium in softened water. 

The ratios of subscripts in the formula can be determined if the elemental composition of an organism growing under particular conditions is known. A unique cell formula can then be established by relating elemental composition to one gram-atom of carbon, ie 9 = 1, then a, p, and 8 are set so that the formula is consistent with known relative elemental weight content of the cells. The formula can be extended to include other macro-elements, such as phosphate and sulphur, if elemental analysis shows these elements to be a significant proportion of cell material. 

Cell growth and metabolic activities are similarly described as a simple chemical reaction. It is also necessary to establish a definite formula for dry cell matter. The elemental composition of certain strains of microorganism is defined by an empirical formula CHaO/3Ns. The general biochemical reaction for biomass production is based on consumption of organic substrate, as shown below. Substrate oxidation is simplified in the following biochemical oxidation ... 

AES is a useful element-specific technique for quantitative determination of the elemental composition of a surface. Although some chemical information is available in principle, the technique is used largely for elemental analysis. Electron beam damage can decompose organic adsorbates and cause damage, particularly on insulating surfaces. In some cases, the beam can reduce metal oxides. 

Applications Applications of IC extend beyond the measurement of anions and cations that initially contributed to the success of the technique. Polar organic and inorganic species can also be measured. Ion chromatography can profitably be used for the analysis of ionic degradation products. For example, IC permits determination of the elemental composition of additives in polymers from the products of pyrolysis or oxidative thermal degradation. The lower detection limit for additives in polymers are 0.1% by PyGC... 

Wu, Z. Rodgers, R. R Marshall, A. G. Two- and three-dimensional van Krevelen diagrams A graphical analysis complementary to the Kendrick mass plot for sorting elemental compositions of complex organic mixtures based on ultrahigh-resolution broadband Fourier transform ion cyclotron resonance mass measurements. Anal. Chem. 2004, 76, 2511-2516. 

Fig. 5. Elemental composition of humic substances representing various solid phase organic matter (SP0M> number of samples = 52)...

In some sediments, downcore variations in the bulk chemical composition are interpretable as records of temporal shifts in the elemental composition of the sinking POM. Such shifts are caused by changes in the production of sinking POM, which are in turn the result of fluctuations in the abundance and diversity of the overlying plankton community. In nearshore sediments, fluctuations in river runoff and lateral transport can lead to shifts in the supply rate of terrigenous organic matter. An example of a nearshore sediment core in which such fluctuations have been recorded is shown in Figure 23.18. 

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