Humic elemental analysis

As with the bulk POM and DOM, the operationally defined fractions of UDOM and humic substances are quantified by elemental analysis and via broad molecular-class detection. Other strategies involve measurement of the natural isotopic composition, both stable and radioactive, of the various fractions. Efforts are underway to develop more sophisticated techniques, such as solid-state NMR and high-resolution mass spectrometry, far identification of specific bonds and functional groups. 

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... 

The concentration of humic acid was determined by TOC analysis. TOCs for the humic stock solutions were normally 2.3 0.1 g/L. Elemental analysis showed that the powdered humic substance was 52 carbon weight. This result indicates that the theoretical maximum of TOC for an 800-mL solution prepared from 4.0 g of humic substances is 2.6 g/L. 

Elemental Analysis. The elemental analyses are presented in Table IV. The atomic ratios H/C for all drinking water samples (nos. 1-10) were between 1.28 and 1.39. These values were comparable to humic acid derived from lake sediments. However, H/C ratios were much lower when compared to the chlorinated model humic substances (e.g., 1.04-1.08 for CFH-1 and CFH-2). Bromine was present in almost negligible quantities, whereas Cl varied between 0.3 and 2.4, and S varied between 0.9 and 2.7 in the drinking water organic matter. All fractions from drinking water showed similar elemental composition. However, they differed from the elemental composition of the CFH samples in all respects, especially in chlorine content. 

Amir, S., Hafidi, M., Merlina, G., Hamdi, H., and Revel, J. C. (2004). Elemental analysis, FTIR, 13C-NMR of humic acids from sewage sludge composting. Agronomie 24,13-18. 

Figure 5.3. A humic acid macromolecule interacting with a surface of a clay mineral. The proposed macromolecular structure of the soil humic acid (HA) is based on the following common average characteristics of humic acids MW 6386 Da elemental analysis (%) C, 53.9 N, 5.0 H, 5.8 0,35.1 S, 0.5 C/N, 10.7 NMR information (%) aliphatic C, 18.1 aromatic C, 20.9 carbohydrate C, 23.7 metoxy C, 4.9 carboxylic C, 8.4 ketone C, 4.5 phenolic C, 4.2 functional groups (cmol/g) carboxyl, 376 phenol, 188 total acidity, 564. The structure was created using the ACD/ChemSketch program. [HA-clay complex Chen s group, unpublished (2008). Individual HA molecule Grinhut et al., 2007.]...

Huffman, E. W. D., and Stuber, H. A. (1985). Analytical methodology for elemental analysis of humic substances. In Humic Substances in Soil, Sediment, and Water. Geochemistry, Isolation, and Characterization, Aiken, G. R., McKnight, D. M., Wershaw, R. L., and Mac-Carthy, P., eds., John Wiley Sons, New York, pp. 433 455. 

Elemental analysis and the detailed characterization require the extraction and purification of soil organic matter. International Humic Substances Society (2008)... 

Some of each of the fractions was acid-washed to remove sodium and reprecipitate the humic acids. A yellow supernatant liquid remained after precipitation of the humic acids, caused by small quantities of fulvic acid. An elemental analysis then was carried out on the dried solids of each fraction. 

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. 

Elemental Analysis. Carbon, hydrogen, nitrogen, oxygen, sulfur, phosphorous, and ash determinations were made on freeze-dried samples of raw foam, and humic and fulvic acids isolated from Como Creek and Suwannee River foam and water samples by Huffman Laboratories (Golden, CO). Trace-metal analysis was performed on freeze-dried Como Creek foam by Huffman Laboratories (Golden, CO). 

Table Vn. Concentrations (in meq/g) of oxygen-containing functional groups in fulvic and humic acids from stream and foam samples from Como Creek and the Suwannee River, using a combination of C NMR data, elemental analysis, and potentiometric titration data.

Organic petrography and organic element analysis reveal that the source of the kerogen is algal (lamosites dominating) while other maceral forms dominate locally to form carbonaceous shale and humic coals. 

The fact that a humic substance is not a pure compound, but is a heterogenous mixture of many compounds with generally similar chemical properties, places an important constraint on all these characterization methods. Examples of the multicomponent mixture problem are presented in the chapters discussing interpretation of elemental analysis, determination of molecular weight, analysis of potentiometric data, and interpretation of infrared and other spectroscopic data. 

Humic substances are from terrestrial sources in overlying soils. Humic substances in the Biscayne aquifer are quite similar to those in surface water in elemental analysis, carbohydrate content, color, molecular weight, C/... 

TABLE 4. Elemented Analysis of Humic Acid from Soils Under Various Climates" and from Various Marine Planktonic Constituents ... 

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). 

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