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.

Total Nitrogen Determination of Various Sample Types: A Comparison of the Hach, Kjeltec, and Kjeldahl Methods

1987 ◽  
Vol 70 (3) ◽  
pp. 410-412
Author(s):  
Kevin L Watkins ◽  
Trygve L Veum ◽  
Gary F Krause
Keyword(s):  
Total Nitrogen ◽  
Sample Type ◽  
N Content ◽  
Nitrogen Determination ◽  
N Sources ◽  
Wide Range ◽  
Determination Methods ◽  
The Mean ◽  
Intermediate Results

Abstract Conventional Kjeldahl analysis with modifications, Kjeltec analysis with block digestion and semiautomated distillation, and the Hach method for determining nitrogen (N) were compared using a wide range of samples. Twenty different sample types were ground and mixed. Each sample type was divided into 5 subsamples which were analyzed for N by each of the 3 methods. In each sample type, differences (P < 0.05) were detected among the 3 N determination methods in 5 of the 20 N sources analyzed. The mean N content over all 20 samples was higher with Kjeldahl analysis (P < 0.05) than with Kjeltec, while Hach analysis produced intermediate results. Results also indicated that the Hach procedure had the greatest ability to detect differences in N content among sample types, being more sensitive than either other method (P < 0.05).

Substitution of Cupric Sulfate for Mercuric Oxide as Catalyst for the Kjel-Foss Instrument

1976 ◽  
Vol 59 (1) ◽  
pp. 219-220
Author(s):  
Larry L Wall ◽  
Charles W Gehrke
Keyword(s):  
Standard Deviation ◽  
Mercuric Oxide ◽  
Experimental Sample ◽  
Cupric Sulfate ◽  
Protein Nitrogen ◽  
Feed Control ◽  
Relative Standard ◽  
Standard Configuration ◽  
Automated Instrument

Abstract A mixture of cupric sulfate and titanium dioxide and cupric sulfate alone were evaluated as possible catalysts to replace mercuric oxide in the determination of protein nitrogen, using the Kjel-Foss automated instrument. It was necessary to modify the instrument to increase the digestion time from 6 to about 12 min to achieve acceptable protein nitrogen recovery with cupric sulfate as the catalyst. An experimental sample set of nitrogen-containing salts and American Association of Feed Control Officials check feed samples were analyzed with the Kjel-Foss instrument in its standard configuration with mercuric oxide and as modified with cupric sulfate as the catalyst. The average per cent nitrogen, standard deviation, and relative standard deviation with mercuric oxide and cupric sulfate were 10.37 and 10.36, 0.040 and 0.042, and 0.53 and 0.56, respectively. The substitution of cupric sulfate for mercuric oxide is feasible, and it eliminates the use of the potential pollutant, mercury.

Direct and Indirect Determination of True Protein Content of Milk by Kjeldahl Analysis: Collaborative Study

1991 ◽  
Vol 74 (2) ◽  
pp. 281-288 ◽  
Author(s):  
David M Barbano ◽  
Joanna M Lynch ◽  
J Richard Fleming
Keyword(s):  
Nitrogen Content ◽  
Protein Content ◽  
Total Nitrogen ◽  
Collaborative Study ◽  
Total Nitrogen Content ◽  
Nonprotein Nitrogen ◽  
Protein Nitrogen ◽  
Nitrogen Determination ◽  
True Protein

Abstract Currently, the reference procedure for determination of the "protein" content of milk is based on measurement of the total nitrogen content of milk by the Kjeldahl method (AOAC method, 920.105). About 6% of the total nitrogen content of milk Is nonprotein nitrogen. Therefore, total nitrogen multiplied by the conversion factor 6.38 overestimates the true protein content of milk on average by about 6%. In the present study, new direct and Indirect methods were developed for measurement of the true protein content of whole milk by Kjeldahl nitrogen determination. Both new methods are sample preparation procedures used to fractionate the nitrogen-containing compounds In milk prior to measurement of the nitrogen content of these fractions by Kjeldahl analysis. The collaborative study consisted of 9 pairs of blind duplicate milk samples that were analyzed for total nitrogen, nonprotein nitrogen, and protein nitrogen by each of 10 laboratories. Both methods for true protein measurement (direct and Indirect) gave acceptable statistical performance characteristics and good agreement between methods. The new direct method requires about half the laboratory analysis work of the indirect method (i.e., total minus nonprotein nitrogen). The methods have been adopted official first action by AOAC as (1) a new method for nonprotein nitrogen determination in milk, (2) a new method (direct) for determination of protein nitrogen content of milk, and {3) an alternative method (indirect) for determination of protein nitrogen content of milk.

scholarly journals Improvement of the Conditions for the Determination of Total Nitrogen in Fish Meal in Kjeldahl Method and Its Comparison with Dumas Method

2011 ◽  
Vol 60 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Takashi KUBOTA ◽  
Tomoko OSHIDA ◽  
Kozue YANAI ◽  
Yuzuru INOUE ◽  
Seiji MATSUI ◽  
...  
Keyword(s):  
Total Nitrogen ◽  
Fish Meal ◽  
Kjeldahl Method

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.

Determination of Kjeldahl Nitrogen in Fertilizers by AOAC Official MethodSM 978.02: Effect of Copper Sulfate as a Catalyst

2014 ◽  
Vol 97 (3) ◽  
pp. 764-767 ◽  
Author(s):  
Dean Abrams ◽  
David Metcalf ◽  
Michael Hojjatie
Keyword(s):  
Total Nitrogen ◽  
Copper Sulfate ◽  
Primary Objective ◽  
Mercuric Oxide ◽  
Copper Salts ◽  
Significant Difference ◽  
Kjeldahl Method ◽  
Aoac Official ◽  
Effect Of Copper ◽  
Kjeldahl Nitrogen

Abstract In AOAC Official MethodSM 955.04, Nitrogen (Total) in Fertilizers, Kjeldahl Method, fertilizer materials are analyzed using mercuric oxide or metallic mercury (HgO or Hg) as a catalyst. AOAC Official MethodSM 970.02, Nitrogen (Total) in Fertilizers is a comprehensive total nitrogen (including nitrate nitrogen) method adding chromium metal. AOAC Official MethodSM 978.02, Nitrogen (Total) in Fertilizers is a modified comprehensive nitrogen method used to measure total nitrogen in fertilizers with two types of catalysts. In this method, either copper sulfate or chromium metal is added to analyze for total Kjeldahl nitrogen. In this study, the part of AOAC Official MethodSM 978.02 that is for nitrate-free fertilizer products was modified. The objective was to examine the necessity of copper sulfate as a catalyst for the nitrate-free fertilizer products. Copper salts are not environmentally friendly and are considered pollutants. Products such as ammonium sulfate, diammonium phosphate, monoammonium phosphate, urea-containing fertilizers such as isobutylene diurea (IBDU), and urea-triazone fertilizer solutions were examined. The first part of the study was to measure Kjeldahl nitrogen as recommended by AOAC Official MethodSM 978.02. The second part of the study was to exclude the addition of copper sulfate from AOAC Official MethodSM 978.02 to examine the necessity of copper sulfate as a catalyst in nitrate-free fertilizers, which was the primary objective. Our findings indicate that copper sulfate can be eliminated from the method with no significant difference in the results for the nitrogen content of the fertilizer products.

scholarly journals Method Performance Study of the Determination of Total Nitrogen in Soy Sauce by the Kjeldahl Method

2005 ◽  
Vol 21 (9) ◽  
pp. 1129-1132 ◽  
Author(s):  
Shintaro NOZAWA ◽  
Akiko HAKODA ◽  
Kenichi SAKAIDA ◽  
Tadanao SUZUKI ◽  
Akemi YASUI
Keyword(s):  
Total Nitrogen ◽  
Soy Sauce ◽  
Performance Study ◽  
Method Performance ◽  
Kjeldahl Method

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.

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