ISSN:
1432-0789
Keywords:
Total N determination
;
Lignin
;
Nitrate
;
Nitrite
;
Kjeldahl method
;
Auto-analyzer
;
Persulphate analysis
;
Dymock/Devarda method
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Various methods were used to determine N in lignin, both directly and in buffered aqueous solutions (pH 7.0 and 5.5) containing lignin and NO 2 \t or lignin and NO 3 ·t . The percentage recovery of N was highly variable, being dependent on the analytical method and on pH. There appeared to be a reaction between lignin and NO 2 ·t or NO 3 ·t during the analytical procedure. The Kjeldahl method achieved a higher recovery of organic N from pure lignin than the persulphate method, but it showed a higher coefficient of variation. In buffered samples containing lignin together with NO 2 ·t or NO 3 ·t , recoveries of NO 2 ·t and NO 3 ·t were considerably lower for the Montgomery and Dymock and the Devarda methods than for the procedure using an auto-analyzer. The former procedures appeared to fix NO x ·t . With the auto-analyzer and the Devarda methods, recovery was increased with increasing pH values. The Kjeldahl method gave very high standard deviations. It proved unreliable for the analysis of organic N in samples containing both lignin and NO x ·t . During the persulphate analysis, significant N losses were calculated, probably because of acid-induced nitrosation or nitration and subsequent volatilization of N during the persulphate analysis itself.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00336140
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