Collaborative Study of an Automated Method for the Determination of Crude Protein in Animal Feeds

1976 ◽  
Vol 59 (1) ◽  
pp. 141-147
Author(s):  
Rodney J Noel
Keyword(s):  
Crude Protein ◽  
Primary Standard ◽  
Collaborative Study ◽  
Dihydrogen Phosphate ◽  
Ammonium Dihydrogen Phosphate ◽  
Animal Feeds ◽  
Automated Method ◽  
Kjeldahl Method ◽  
Good Agreement

Abstract An automated macro Kjeldahl instrument determines per cent protein at the rate of 20 samples/hr. The methodology involved is similar to the present official final action Kjeldahl method, sec. 7.016. The 2 methods were compared in a collaborative study. Sixteen animal feeds, 4 meats, tryptophan, ammonium dihydrogen phosphate NBS standard, and ammonium sulfate primary standard were analyzed by the participating laboratories. The data were treated statistically and the results showed good agreement between the 2 methods. The automated method has been adopted as official first action for the determination of crude protein in feeds, plants, and cereal foods.

Collaborative Study of a Semiautomated Method for the Determination of Crude Protein in Animal Feeds

1976 ◽  
Vol 59 (1) ◽  
pp. 134-140 ◽  
Author(s):  
Rodney J Noel ◽  
Larry G Hambleton
Keyword(s):  
Crude Protein ◽  
Primary Standard ◽  
Collaborative Study ◽  
Dihydrogen Phosphate ◽  
Ammonium Dihydrogen Phosphate ◽  
Animal Feeds ◽  
Kjeldahl Method ◽  
Feed Samples ◽  
Semiautomated Method

Abstract A semiautomated method consisting of digestion of animal feeds in a block digestor and determination of ammonia by ammonia-salicylate reaction has been studied collaboratively, along with the official final action Kjeldahl method, sec. 7.016. Each collaborator analyzed 16 feed samples, tryptophan, ammonium dihydrogen phosphate NBS standard, and ammonium sulfate primary standard. Statistical analysis showed that the 2 methods agreed. The semiautomated method has been adopted as official first action.

Determination of Crude Protein in Animal Feeds, Using Block Digestion Followed by Steam Distillation: Collaborative Study

1979 ◽  
Vol 62 (2) ◽  
pp. 290-291
Author(s):  
Rodney J Noel
Keyword(s):  
Statistical Analysis ◽  
Crude Protein ◽  
Steam Distillation ◽  
Collaborative Study ◽  
Alternative Technique ◽  
Animal Feeds ◽  
Ammonia Determination ◽  
Kjeldahl Method ◽  
Feed Samples

Abstract A method consisting of digesting animal feeds in a block digestor and determining ammonia by steam distillation followed by titration has been evaluated and compared with the official final action Kjeldahl method, 7.016. Fifteen laboratories analyzed 5 feed samples and lysine monohydrochloride. Statistical analysis showed that results from the 2 methods were comparable. The distillation technique has been adopted as official first action as an alternative technique for ammonia determination from the digest of the official final action block digestor method, 7.B11.

Comparison of HgO and CuS04 as Digestion Catalysts in Manual Kjeldahl Determination of Crude Protein in Animal Feeds: Collaborative Study

1984 ◽  
Vol 67 (5) ◽  
pp. 869-877 ◽  
Author(s):  
Peter F Kane ◽  
◽  
A Altemeier ◽  
L L Austin ◽  
C V Beggs ◽  
...  
Keyword(s):  
Crude Protein ◽  
Animal Feed ◽  
Collaborative Study ◽  
Matched Pairs ◽  
Animal Feeds ◽  
Kjeldahl Method ◽  
Environmental Considerations ◽  
Standard Deviations ◽  
Digestion Step

Abstract The official AOAC manual Kjeldahl method for determining crude protein in animal feeds, 7.015, uses HgO as a catalyst in the digestion step. Because of environmental considerations, there is considerable interest in alternative catalysts. A collaborative study compares the official HgO-catalyzed method and an alternative using CuS04. Fifty-four samples consisting of blind duplicates of closely matched pairs, representing a range of animal feed materials and 2 standard materials, were analyzed once by each method. Results were returned by 22 laboratories. Means and standard deviations between methods were comparable. The CuS04-catalyzed method has been adopted official first action.

Generic Combustion Method for Determination of Crude Protein in Feeds: Collaborative Study

1989 ◽  
Vol 72 (5) ◽  
pp. 770-774 ◽  
Author(s):  
Rose A Sweeney
Keyword(s):  
Crude Protein ◽  
Collaborative Study ◽  
Combustion Method ◽  
Performance Requirements ◽  
General Terms ◽  
Relative Standard ◽  
Kjeldahl Method ◽  
Standard Deviations ◽  
And Performance

Abstract Nine laboratories participated in a collaborative study on determination of crude protein in animal feeds to compare a generically described combustion method with the AOAC mercury catalyst Kjeldahl method (7.015). The combustion method was written in general terms of method principle, apparatus specifications, and performance requirements. The sample set comprised closely matched pairs of feed ingredients and mixed products ranging from 10 to 90% protein. Ten pairs ground to 0.5 mm were the focus of the study; 4 pairs were ground to 1.0 mm for comparison. Nicotinic acid and lysine monohydrochloride were included as standards. Collaborators were instructed to report their results for performance checks using materials supplied. Only one laboratory failed to meet the proposed limits. Seven laboratories used the LECO Model FP-228 analyzer and 2 used the LECO CHN 600 analyzer. For the 0.5 mm pairs, repeatability standard deviations (sr) ranged from 0.09 to 0.58 for the Kjeldahl method and from 0.14 to 0.33 for the combustion method, with a pooled sr value of 0.28 and relative standard deviation (RSDr) of 0.59%. Reproducibility standard deviations (SR) ranged from 0.23 to 0.86 (Kjeldahl) and from 0.30 to 0.61 (combustion), with a pooled sR value of 0.52 and RSDR of 1.10%. Grand means for the samples ground to 0.5 mm were 47.65% protein by the combustion method and 47.41% protein by the Kjeldahl method. For samples ground to 1.0 mm, corresponding values were 31.82 and 31.50% protein. The generic combustion method has been approved interim official first action.

Comparison of Kjeldahl Method for Determination of Crude Protein in Cereal Grains and Oilseeds with Generic Combustion Method: Collaborative Study

1993 ◽  
Vol 76 (4) ◽  
pp. 780-786 ◽  
Author(s):  
Ronald C Bicsak ◽  
◽  
R Boles ◽  
R Cathey ◽  
V Collins ◽  
...  
Keyword(s):  
Crude Protein ◽  
Animal Feed ◽  
Collaborative Study ◽  
Combustion Method ◽  
Cereal Grains ◽  
Relative Standard ◽  
Kjeldahl Method ◽  
Repeatability And Reproducibility ◽  
Standard Deviations

Abstract Seven laboratories participated in a collaborative study to extend the applicability of the AOAC generic combustion method for determination of crude protein in animal feed (990.03) to include determination in cereal grains and oilseeds. In the study, method 990.03 was compared with the AOAC mercury catalyst Kjeldahl method for determination of protein in grains (979.09) and crude protein in animal feed (954.01). The study also evaluated the effect on the results of fineness of grind. For determination of crude protein in grains and oilseeds by the combustion method, standard deviations for repeatability and reproducibility ranged from 0.10 to 0.37 and from 0.25 to 0.54, respectively, and relative standard deviations for repeatability and reproducibility ranged from 0.77 to 2.57% and from 1.24 to 3.15%, respectively. The combustion method was adopted first action by AOAC International for determination of crude protein in cereal grains and oilseeds containing 0.2- 20% nitrogen.

Combustion Method for Determination of Crude Protein in Meat and Meat Products: Collaborative Study

1993 ◽  
Vol 76 (4) ◽  
pp. 787-793 ◽  
Author(s):  
Brink Marcia King ◽  
Sebranek Joseph G. ◽  
◽  
C Anthony ◽  
P Coleman ◽  
...  
Keyword(s):  
Crude Protein ◽  
Collaborative Study ◽  
Meat Product ◽  
Meat Products ◽  
Combustion Method ◽  
Relative Standard ◽  
Kjeldahl Method ◽  
Standard Deviations ◽  
Meat Samples

Abstract Twelve laboratories participated in a collaborative study to compare a combustion method with the AOAC mercury catalyst Kjeldahl method (928.08) for the determination of crude protein in meat and meat products. Three different combustion instruments were used; consequently, the combustion method for this study is written in generic terms describing the principle, the apparatus specifications, and the performance requirements needed. Fifteen sample pairs were used for the study; each pair consisted of the same commercial meat product from each of 2 different manufacturers. Protein content of all samples ranged from about 10 to 20%. In addition, nicotinic acid and lysine monohydrochloride were used as standards to assess combustion equipment performance. All laboratories and all instruments performed the combustion method satisfactorily on the basis of results for the standards. For the meat samples, repeatability standard deviations (sr) ranged from 0.11 to 0.40 for the Kjeldahl method and from 0.12 to 0.41 for the combustion method; the repeatability relative standard deviations (RSDr) ranged from 0.82 to 2.41% and from 0.60 to 2.23% for the Kjeldahl and combustion methods, respectively. Reproducibility standard deviations (SR) ranged from 0.20 to 0.49 for the Kjeldahl method and from 0.18 to 0.46 for the combustion method, whereas the reproducibility relative standard deviations (RSDR) ranged from 1.59 to 2.84% for the Kjeldahl method and from 1.32 to 3.35% for the combustion method. Overall grand means were 15.59% protein for the Kjeldahl method and 15.75% protein for the combustion method. The combustion method was adopted first action by AOAC International.

Comparison of HgO and CuS04/Ti02 as Catalysts in Manual Kjeldahl Digestion for Determination of Crude Protein in Animal Feed: Collaborative Study

1987 ◽  
Vol 70 (5) ◽  
pp. 907-911 ◽  
Author(s):  
Peter F Kane
Keyword(s):  
Confidence Level ◽  
Crude Protein ◽  
Animal Feed ◽  
Collaborative Study ◽  
Environmental Concerns ◽  
Matched Pairs ◽  
Animal Feeds ◽  
Alternative Method ◽  
Kjeldahl Digestion

Abstract Because of environmental concerns about HgO, and because of lengthy digestion requirements for HgO and CuS04, interest in alternative catalysts for the Kjeldahl determination of animal feeds remains high. A digestion system using a mixed CuS04/Ti02 catalyst has been found to reduce digestion times to 40 min. A collaborative study was carried out to compare this system to the official AOAC HgO method, 7.015. Thirty-eight samples, consisting of blind duplicates of closely matched pairs and 2 standard materials, were analyzed once by each method. Results were received from 13 laboratories. Means and standard deviations of individual samples were comparable, with an overall difference of grand means of 0.005% protein. With only one exception, analyses of variance showed no significant method difference at the 95% confidence level. The CuS04/Ti02 method has been approved interim official first action as an alternative method for determination of crude protein in animal feed

Comparison of Three Methods for Determination of Crude Protein in Meat: Collaborative Study

1982 ◽  
Vol 65 (6) ◽  
pp. 1339-1345 ◽  
Author(s):  
Francis B Suhre ◽  
Paul A Corrao ◽  
Angeline Glover ◽  
Anthony J Malanoski ◽  
◽  
...  
Keyword(s):  
Crude Protein ◽  
Steam Distillation ◽  
Collaborative Study ◽  
Distillation Method ◽  
Reference Procedure ◽  
Kjeldahl Method ◽  
Aoac Method ◽  
Repeatability And Reproducibility ◽  
Standard Deviations

Abstract A study was designed to compare the Kjel-Foss automated macro-Kjeldahl method and a block digestion- steam distillation method. The official AOAC Kjeldahl method was used as a reference procedure. Six products with a crude protein range of 10-30% were analyzed by 23 laboratories. Five laboratories analyzed the samples by the official AOAC method, 8 laboratories used the automated Kjel-Foss method, and 11 laboratories used the block digestion with steam distillation method. Standard deviations for each product and each method for both repeatability and reproducibility are given. The block digestion- steam distillation method has been adopted official first action.

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