Nitrogen, determination organic matter

Back titrations are common in soil analysis, as they are used in both nitrogen and organic matter determinations. Back titrations are highly valuable analytical techniques and are applicable to other environmental analyses as well. 

Farquhar, G. D., B. K. Henry J. M. Styles, 1997. A rapid on-line technique for determination of oxygen isotope composition of nitrogen-containing organic matter and water. Rapid Commun. Mass Spectrom. 11 1554-1560. 

There is one case where total destruction of soil organic matter and its constituents is standard practice and that is in the determination of nitrogen... 

Total and nitrate nitrogen were determined by Kjeldahl and colorimetric methods, respectively (29,30). Organic matter was determined by the wet oxidation method of Walkley (31). Soil pH was determined with a glass electrode in a 2 1 mixture of water and soil. 

Hydrogen in these particles is correlated with carbon and is presumed to occur in organic matter. Analyses of the isotopic composition of hydrogen (McKeegan et al., 2006) show D/H enrichments (Fig. 12.12). The D/H ratios overlap those of H20 in comets but are well below those determined for organic matter in CP IDPs. Measurements of nitrogen isotopes show 15N enhancements, suggesting an interstellar contribution. 

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