Humic materials elemental analyses

The OM appears to be essentially of marine planktonic origin, as deduced from (i) elemental analysis (the atomic ratios 0/C and H/C values of 0.15 and 1.29 % in HA and 0.40 and 1.55% in FA, respectively, indicate that these humic compounds originated from marine aliphatic organic matter) (ii) FTIR analysis of humic materials (Fig. 2. spectra obtained for HA show these humics are rich with aliphatic stmetures which is... 

Summary The possibility of direct synthesis of silicon oi anic compounds based on hydrolysis-resistant organic derivatives of silicon by using biogenic silica (from siliceous rocks) as a new raw material is discussed. The complex triethylphosphate with silica, the ammonium salts of tricatechol, and humic acids of monosilicic acids were obtained. Products were identified by proton magnetic resonance spectroscopy, IR spectrophotometry, or elemental analysis. 

Insofar as humin is an insoluble macromolecular residue, it has mostly been examined by techniques amenable to solid materials (i.e., elemental analysis, infrared, solid-state NMR, and ESR spectroscopy). Degradative techniques such as oxidation, reduction, and pyrolysis have also been employed. All these methods have been used for the study of humic substances and excellent reviews of the various methods are provided by Schnitzer and Khan (1972, 1978) as well as by Stevenson (1982). 

The purpose of this section is to provide a brief review of the methods and techniques commonly used in the elemental analysis of humic substances with special emphasis placed on areas that may cause difficulties in their analysis. There are few specific references to methods of elemental analysis of humic substances. A computerized search of Chemical Abstracts since 1966 revealed no references to techniques of elemental analysis when elemental analysis was cross-referenced with humic or fulvic acid materials. In general, the methods of analysis have been developed to be applicable to a wide range of organic materials. However, it should be pointed out that most methods have been validated on the basis of the analysis of stable, nonhy-groscopic, nonvolatile, pure compounds and not heterogeneous mixtures. 

Nevertheless, it is surprising how often one refers to elemental analysis to confirm the presence of a humic or fulvic acid. It is useful in determining whether a brown, macromolecular acidic material is from a coal, soil, marine sediment, or kerogen. It is most useful in characterizing structural trends in a specific environment, such as in sediments or soil profiles. Atomic ratios, especially 0/C ratios, are the simplest way to display elemental composition of humates. They also help one devise hypothetical structures for humates. As a guide in the synthesis of artificial humic substances, they are invaluable. In addition, atomic ratios help the investigator identify nonhumate contaminants. 

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