NITROGEN DETERMINATION IN WHEAT LEAVES

1950 ◽  
Vol 28c (6) ◽  
pp. 745-753 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Salicylic Acid ◽  
Organic Nitrogen ◽  
Nitrate Nitrogen ◽  
Soluble Nitrogen ◽  
Mercuric Oxide ◽  
Nitrogen Fractions ◽  
Nitrogen Determination ◽  
Satisfactory Method ◽  
Kjeldahl Method ◽  
Wheat Leaves

A survey of the more promising modifications of the Kjeldahl method for nitrogen determination indicates that the method using mercuric oxide as the catalyst as recommended by the Association of Official Agricultural Chemists is the most satisfactory. However small discrepancies were found when this method was applied to wheat leaves fractionated into soluble and protein (actually coagulable and indiffusible) nitrogen fractions. This method includes all the nitrate nitrogen in wheat leaves together with the organic nitrogen even when no pretreatment with salicylic acid is used. A simple and satisfactory method of separating coagulable and indiffusible nitrogen from soluble nitrogen in wheat leaves and seedlings is described.

Zirconium Dioxide, A New Catalyst, in the Kjeldahl Method for Total Nitrogen Determination

1974 ◽  
Vol 57 (5) ◽  
pp. 1228-1230 ◽  
Author(s):  
William Glowa
Keyword(s):  
Total Nitrogen ◽  
Zirconium Dioxide ◽  
Mercuric Oxide ◽  
Cupric Sulfate ◽  
Nitrogen Determination ◽  
Mixed Catalyst ◽  
Kjeldahl Method

Abstract The standard Kjeldahl method for the determination of total nitrogen in fertilizers, feeds, foods, and beverages has been modified to eliminate the use of mercuric oxide, which is poisonous to the environment. A new mixed catalyst, consisting of 0.60 g cupric sulfate and 0.20 g zirconium dioxide in combination or 0.70 g zirconium dioxide alone, is recommended to replace the 0.70 g or more of mercuric oxide used in all official macro Kjeldahl methods.

Tellurium as Catalyst in Semimicro Kjeldahl Method for Total Nitrogen Determination

1982 ◽  
Vol 65 (4) ◽  
pp. 786-790
Author(s):  
Christina F-H Liao
Keyword(s):  
Total Nitrogen ◽  
Organic Nitrogen ◽  
Complete Recovery ◽  
Nitrogen Compounds ◽  
Nitrogen Determination ◽  
Plant Soil ◽  
Clearing Time ◽  
Kjeldahl Digestion ◽  
Kjeldahl Method ◽  
Agricultural Materials

Abstract A modified semimicro Kjeldahl procedure is described for total nitrogen determination in agricultural materials and refractory organic nitrogen compounds, in which tellurium, alone or in combination with copper, is used as a catalyst. Tellurium alone is adequate for complete recovery of nitrogen from nicotinic acid if the acid:salt ratio is carefully controlled to nearly 1. However, when a mixture of tellurium and copper is used, complete nitrogen recovery could be obtained at a higher acidrsalt ratio. Use of a mixture also reduces clearing time when compared with copper alone in the Kjeldahl digestion. For samples containing nitrate, a Devarda's alloy (Cu:Al:Zn = 10:9:1) is proposed as a reducing agent in the pretreatment procedure to convert nitrate to ammonium in 6N H2SO4, with subsequent digestion of the sample by using a mixture of K2S04-catalyst and concentrated H2SO4. The proposed method is applicable for total nitrogen determination including NO3-N in plant, soil, and fertilizer samples.

Novel Metabolism of Nitrogen in Plants

2005 ◽  
Vol 60 (3-4) ◽  
pp. 265-271 ◽  
Author(s):  
Hiromichi Morikawa ◽  
Misa Takahashi ◽  
Atsushi Sakamoto ◽  
Manami Ueda-Hashimoto ◽  
Toshiyuki Matsubara ◽  
...  
Keyword(s):  
Plant Species ◽  
Reactive Nitrogen Species ◽  
Organic Nitrogen ◽  
Nitrate Nitrogen ◽  
Nitro Compounds ◽  
Wild Type Plant ◽  
Wild Type ◽  
Physiological Relevance ◽  
Kjeldahl Method ◽  
Β Carotene

Abstract Our previous study showed that approximately one-third of the nitrogen of 15N-labeled NO2 taken up into plants was converted to a previously unknown organic nitrogen (hereafter designated UN) that was not recoverable by the Kjeldahl method (Morikawa et al., 2004). In this communication, we discuss metabolic and physiological relevance of the UN based on our newest experimental results. All of the 12 plant species were found to form UN derived from NO2 (about 10-30% of the total nitrogen derived from NO2). The UN was formed also from nitrate nitrogen in various plant species. Thus, UN is a common metabolite in plants. The amount of UN derived from NO2 was greatly increased in the transgenic tobacco clone 271 (Vaucheret et al., 1992) where the activity of nitrite reductase is suppressed less than 5% of that of the wild-type plant. On the other hand, the amount of this UN was significantly decreased by the overexpression of S-nitrosoglutathione reductase (GSNOR). These findings strongly suggest that nitrite and other reactive nitrogen species are involved in the formation of the UN, and that the UN-bearing compounds are metabolizable. A metabolic scheme for the formation of UN-bearing compounds was proposed, in which nitric oxide and peroxynitrite derived from NO2 or endogenous nitrogen oxides are involved for nitrosation and/or nitration of organic compounds in the cells to form nitroso and nitro compounds, including N-nitroso and S-nitroso ones. Participation of non-symbiotic haemoglobin bearing peroxidase-like activity (Sakamoto et al., 2004) and GSNOR (Sakamoto et al., 2002) in the metabolism of the UN was discussed. The UN-bearing compounds identified to date in the extracts of the leaves of Arabidopsis thaliana fumigated with NO2 include a ⊿2- 1,2,3-thiadiazoline derivative (Miyawaki et al., 2004) and 4-nitro-β-carotene.

Uncertainty of nitrogen determination by the Kjeldahl method

2003 ◽  
pp. 273-279
Author(s):  
Thomas Anglov ◽  
Inge M. Petersen ◽  
Jesper Kristiansen
Keyword(s):  
Nitrogen Determination ◽  
Kjeldahl Method

The Kjeldahl Method for Organic Nitrogen

1966 ◽  
Vol 49 (2) ◽  
pp. 481-481
Author(s):  
John A Brabson
Keyword(s):  
Organic Nitrogen ◽  
Kjeldahl Method

VARIETAL DIFFERENCES IN BARLEYS AND MALTS: VI. AUTOLYTIC PROTEOLYTIC ACTIVITY OF MALT AND ITS CORRELATIONS WITH WORT NITROGEN AND BARLEY NITROGEN FRACTIONS

1939 ◽  
Vol 17c (8) ◽  
pp. 239-246 ◽  
Author(s):  
C. Alan Ayre ◽  
J. Ansel Anderson
Keyword(s):  
Proteolytic Activity ◽  
Total Nitrogen ◽  
Malting Quality ◽  
Soluble Nitrogen ◽  
Varietal Differences ◽  
Nitrogen Fractions ◽  
Partial Correlations ◽  
Average Activity

The proteolytic activity of 144 samples of malt, representing 12 varieties grown at 12 experimental stations in Canada, was determined by an autolytic method. Certain varieties differed widely in average activity (Olli, 291; O.A.C. 21, 235; and Wisconsin 38, 150 units), those of poor malting quality tending to give low values. The spread between station means was also large (Beaverlodge, 284; and Nappan, 149 units).The correlations between proteolytic activity, barley nitrogen fractions, total barley nitrogen, and wort nitrogen (data given in an earlier paper), were also studied. Intra-varietal partial correlations independent of total nitrogen, between proteolytic activity and nitrogen fractions, were all insignificant. Corresponding inter-varietal partial correlations were insignificant for insoluble and alcohol-soluble nitrogen, but highly significant for salt-soluble barley nitrogen and wort nitrogen. A close inter-varietal relation was found between proteolytic activity and salt-soluble barley nitrogen, and it was impossible to demonstrate that these two properties influenced wort nitrogen independently.

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