Crude Protein--Kjeldahl Method, Boric Acid Modification

2009 ◽  
Author(s):  
AACC Technical
Keyword(s):  
Boric Acid ◽  
Crude Protein ◽  
Acid Modification ◽  
Kjeldahl Method

Revised Kjeldahl Total Nitrogen Method for Feeds and Premixes

1972 ◽  
Vol 55 (5) ◽  
pp. 984-985
Author(s):  
Robert Odland
Keyword(s):  
Boric Acid ◽  
Refractory Material ◽  
Total Nitrogen ◽  
Crude Protein ◽  
Analysis Time ◽  
Acid Method ◽  
Kjeldahl Method ◽  
Complete Digestion

Abstract A Kjeldahl method for equivalent crude protein in feeds was modified by using a smaller sample (0.25 g) and smaller amounts of reagents in order to reduce analysis time and cut costs. A 6% CuSO4 catalyst was used for the complete digestion of refractory material. Winkler’s boric acid method was modified by including a 90% pretitration to insure complete retention of ammonia so that only one standardized reagent is needed.

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.

scholarly journals Prediction of bovine milk true protein content by mid-infrared spectroscopy

2011 ◽  
Vol 41 (8) ◽  
pp. 1472-1474 ◽  
Author(s):  
Bruno Garcia Botaro ◽  
Cristina Simões Cortinhas ◽  
Lucinéia Mestieri ◽  
Paulo Fernando Machado ◽  
Marcos Veiga dos Santos
Keyword(s):  
Protein Content ◽  
Crude Protein ◽  
Bovine Milk ◽  
Dairy Herds ◽  
Protein Determination ◽  
Mid Infrared ◽  
Kjeldahl Method ◽  
Bulk Tank ◽  
One Year ◽  
True Protein

The aim of this study was to estimate the concentration of milk true protein (TP) by mid-infrared absorbance method (MIR) in samples from bulk tank of dairy herds, and to determine the correlation between the results of TP of milk determined by Kjeldahl and MIR. Forty nine dairy herds were selected (17 Holstein, 6 Jersey and 26 Girolando) for monthly collections of samples from bulk tanks during the period of one year (284 samples). Fat, lactose, crude protein and total solids were firstly determined by MIR, and then analyzed for total and true protein by Kjeldahl method. The regression equation to estimate TP contents based on MIR crude protein determination was as follows: TP=0.0021+(1.0104xCP), where: TP is the content of true protein, CP is the crude protein content determined by the MIR method, and 0.0155 is the model error term.

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.

Comparison of LECO FP-228 "Nitrogen Determinator" with AOAC Copper Catalyst Kjeldahl Method for Crude Protein

1987 ◽  
Vol 70 (6) ◽  
pp. 1028-1030 ◽  
Author(s):  
Rose A Sweeney ◽  
Paul R Rexroad
Keyword(s):  
Crude Protein ◽  
Copper Catalyst ◽  
Combustion Method ◽  
Rapid Analysis ◽  
Nitrogen Gas ◽  
Average Recovery ◽  
Nitrogen Levels ◽  
Kjeldahl Method ◽  
Standard Deviations

Abstract The LECO FP-228 "Nitrogen Determinator" was compared with the AOAC copper catalyst Kjeldahl method, 7.033-7.037, for the determination of crude protein in feed materials. The completely microprocessor- controlled instrument determines nitrogen by measuring the nitrogen gas following combustion of the sample; it was easy to operate and broadly applicable. A wide variety of feed materials of various nitrogen levels were analyzed in one mixed sequence. Results were precise, accurate, and rapid. Analysis time for one sample was approximately 3 min. Fourteen samples containing 2.5-15.5% N were selected for study and consisted of meals, grains, forages, and standard organic materials. The overall mean for the 14 samples by the LECO combustion method was 8.61% N compared with an overall mean of 8.58% N for the AOAC Kjeldahl method. Within-sample standard deviations for the LECO combustion method ranged from 0.013 to 0.052% N with a pooled standard deviation (SD) of 0.033% N for the 14 samples. Standard deviations for the AOAC Kjeldahl method ranged from 0.006 to 0.035% N with a pooled SD of 0.022% N. Combined average recovery of nitrogen from tryptophan, lysine- HC1, and EDTA determined by the LECO combustion method was 99.94% compared to 99.88% determined by the AOAC Kjeldahl method.

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