Also Kjeldahl method

Devarda s Method. Nitrogen in nitrates or nitric acid also may be deterrnined by the Kjeldahl method or by Devarda s method. The latter is both convenient and accurate when no organic nitrogen is present. The nitrate is reduced by Devarda s alloy to ammonia in an alkaline solution. The ammonia is distilled and titrated with standard acid. 

Bound amino spacer or immobilized protein may be determined also by the Kjeldahl method (Protocol 1.1.6). 

Jacobs (Ref 12) stated that AN is usually estimated in dusts by detg the NHS content of a sample either by nesslerization or by the m-xylenol reagent. When the dust also contains nitrocompds (such as nitrated derivs of toluene), it is necessary to make a disen in the presence of an alkali (as in the Kjeldahl method) and then test the distillate by one of the above reagents... 

Ammonium Dichromate, Analytical Procedures. Accdg to Taylor and Rickenbach(See Ref lb), above, the methods of its analysis are identical with those of K dichromate, except that the total ammonia should be detd by the Kjeldahl method. See also under Ammonium Chromate and US Federal Specification OA-498a Barium Dlchromate, BaCr20 , mw 353.38 red, monocl crysts mp ( ) sol in hot coned H2S04 decompd by w. Can be prepd by action of a soln of chromic acid on freshly pptd Ba... 

Our assumption is that the lower values obtained for nitrogen linked by this fixing method perhaps cannot be determined by the Kjeldahl method. Also, the products obtained mechanochemically and those of the combustion residue may have different structures. 

The standard procedure of nitrogen determination by many laboratories is the Kjeldahl method (ASTM D-3179 ISO 333), although there are the standard methods that involve the Dumas technique (DIN 51722) and the gasification procedure (DIN 15722). Neutron activation analysis has also been proposed for the determination of nitrogen in coal, coal ash, and related products (Volborth, 1979a). 

Numerous inorganic species can be determined by titration with strong acids or bases. For example, ammonium salts are determined by conversion to ammonia with strong base and distillation in the Kjeldahl apparatus. Also, inorganic nitrates and nitrites can be determined using Kjeldahl method by reducing these species to ammonium ion. 

The authors found that the determination of nitrogen in PV.N in a nitrometer or by the Kjeldahl method did not give reliable results. It was ncccssar> to use the Dumas method. According to Diepold [25] the method of titration with Fe 11 also gives reliable results. 

Protein content in the yeast biomass was also determined by the Kjeldahl method using the conversion factor of 6.25. Total carbohydrates in yeast biomass were determined by the anthrone method [21]. RNA content was determined by the Schmidt-Thannhauser method as described in Benthin et al. [22]. Fat content was determined in dried cells by a Soxhlet extraction procedure using petroleum ether (60-80 °C) as solvent [23]. Ash content was determined by igniting the samples at 575 °C for 5 h, both for the feedstock and yeast biomass. All results are reported on the dry basis. 

In the early studies of ammonium fixation there was much uncertainty as to the amount of fixed ammonium present in untreated soils. The capacity of the soil for fixing ammonium could be determined readily by the methods already mentioned, but such techniques furnished no information on the amount of fixed ammonium present initially. Since surface soils usually fixed less ammonium than did subsoils, it seemed likely that this was because the surface soils already contained fixed ammonium, and also potassium. Determination of naturally-occurring fixed ammonium was difficult because it was not known if the Kjeldahl method for total nitrogen actually accounted for all of the fixed... 

Nitrogen was initially determined by the inert gas fusion technique but the results were poor. The measurement was therefore repeated by the classical Kjeldahl method which provided data not only far more consistent with the silicon nitride composition but also more precise. The former technique does not seem appropriate for high nitrogen concentration. 

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