Total Nitrogen in Fertilizer: Collaborative Study

1978 ◽  
Vol 61 (2) ◽  
pp. 299-306
Author(s):  
Paul R Rexroad ◽  
Gary F Krause
Keyword(s):  
Total Nitrogen ◽  
Collaborative Study ◽  
Oxidation Catalyst ◽  
Official Method ◽  
Probability Level ◽  
Sulfate Sulfur ◽  
Powder Method ◽  
Modified Method ◽  
Accuracy And Precision ◽  
Cent Nitrogen

Abstract A modified comprehensive nitrogen method, using 0.4 g C11SO4 as catalyst, is presented. This method plus a modified Raney powder method (mercury-free) with no metallic oxidation catalyst are compared with the AOAC comprehensive nitrogen method. Results from 19 collaborating laboratories for 11 samples are evaluated. The modified Raney method gave significantly low results on 2 samples: 21-7-14 (nitric phosphates-non-sulfate sulfur) and tryptophan. The results for the average per cent nitrogen for 11 samples from the modified comprehensive nitrogen method were comparable to those from the official method at the 95 % probability level; the overall pooled standard deviations were also similar. In this collaborative study, the modified method (with copper) was equal in accuracy and precision to the official method (with mercury). The modified comprehensive nitrogen method has been adopted as official first action.

Total Nitrogen in Fertilizers

1968 ◽  
Vol 51 (4) ◽  
pp. 851-857
Author(s):  
Paul R Rexroad ◽  
Gary F Krause
Keyword(s):  
Total Nitrogen ◽  
Collaborative Study ◽  
New Method ◽  
Official Method ◽  
Powder Method ◽  
Catalyst Powder

Abstract A three-laboratory collaborative study was made of the comprehensive nitrogen method and the new Raney catalyst powder method for total nitrogen in fertilizers. Both methods worked quite well and, with minor modifications, they should provide the basis for a broader collaborative stvidy to provide an official method for total nitrogen in fertilizer applicable to all samples. The limitations of method 2.045 are reviewed and a rephrasing of the official applications of the method is recommended. Further work is recommended toward adoption of a new method and possible deletions or change of status in current official methods.

Mercury-Free Raney Catalyst Method for Total Nitrogen in Fertilizers

1974 ◽  
Vol 57 (1) ◽  
pp. 10-13
Author(s):  
Frank J Johnson ◽  
Terry C Woodis ◽  
James M Cummings
Keyword(s):  
Total Nitrogen ◽  
Digestion Time ◽  
Sulfate Sulfur ◽  
Powder Method ◽  
Modified Method ◽  
Catalyst Powder ◽  
Considerable Range

Abstract The original Raney catalyst powder method for total nitrogen was shown not to be applicable to nitric phosphates containing non-sulfate sulfur. Interference by the non-sulfate sulfur was eliminated by the addition of morin, a mordant dye, before the reduction. The method was modified further by omitting HgO, a possible pollutant, from the digestion and by shortening the digestion time. The modified method is highly rugged for a considerable range of fertilizer materials.

Total Nitrogen Methods—Applicable to All Fertilizer Samples

1970 ◽  
Vol 53 (3) ◽  
pp. 450-456
Author(s):  
Paul R Rexroad ◽  
Gary F Krause
Keyword(s):  
Salicylic Acid ◽  
Total Nitrogen ◽  
Collaborative Study ◽  
Official Method ◽  
Chromium Powder ◽  
Powder Method ◽  
New Methods

Abstract An extensive collaborative study was conducted to evaluate a comprehensive nitrogen method and a Raney powder method for acceptance as official methods. Twenty-nine laboratories participated; 10 samples were used and the new methods were compared to the official method, 2.045 (sulfuric-salicylic acid). Evaluation of the data and overall consideration lead to the recommendation that both new methods be adopted as official. It is recommended that 2.047 (reduced iron) and 2.049 (chromium powder) be deleted as official methods.

scholarly journals Fine Tuning a Bile-Enzymatic-Gravimetric Total Dietary Fiber Method

1997 ◽  
Vol 80 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Kenneth J Cranker ◽  
Katherine M Phillips ◽  
Maria Carmen Rita V Gonzales ◽  
Kent K Stewart
Keyword(s):  
Standard Deviation ◽  
Dietary Fiber ◽  
Collaborative Study ◽  
Original Method ◽  
Fine Tuning ◽  
Official Method ◽  
Total Dietary Fiber ◽  
Modified Method ◽  
Relative Standard ◽  
Wet Weight

Abstract A recently proposed bile-enzymatic-gravimetric total dietary fiber (TDF) method was modified and the new procedure was compared with the original method, the traditional AOAC enzymatic-gravimetric determination (AOAC Official Method 985.29), and another simplified AOAC procedure by analyzing several diet composites, including National Institute of Standards and Technology 1548 total diet reference material. The original and modified bile-enzymatic-gravimetric procedures also were compared by analyzing 9 food samples from a collaborative study of the original method. The modified method consistently yielded values about 10% lower than the original method but closer to reference values and to values from AOAC Offical Method 985.29, suggesting results that are more in line with accepted TDF standard methodology. Our modified method was used to analyze 180 fresh-frozen diet composites with TDF values ranging from 0.6 to 3.2 g/100 g wet weight. Samples were from 2 multicenter feeding studies sponsored by the National Heart, Lung and Blood Institute: DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activity) and DASH (Dietary Approaches to Stop Hypertension). The mean relative standard deviation (RSD) for duplicate analyses was 1.1%. For 40 assays of a quality control diet composite over 9 months, the standard deviation was 0.1 g/100 g wet weight (4.9% RSD), indicating the method’s excellent precision for routine use.

Collaborative Study of Improvements in the Distillation Procedure of the Official Method for Formaldehyde in Maple Sirup

1973 ◽  
Vol 56 (1) ◽  
pp. 132-134
Author(s):  
Calixte Hébert
Keyword(s):  
Collaborative Study ◽  
Official Method ◽  
Distillation Method ◽  
Modified Method ◽  
Quantitative Extraction ◽  
Coefficients Of Variation ◽  
Excellent Control ◽  
Final Operation

Abstract A collaborative study was conducted to show that in the quantitative extraction of formaldehyde from maple sirup by the official final action controlled distillation method, 31.184—31.189, accuracy is increased by the use of a thermostatically controlled flask heater, together with the proper insulation of the glass apparatus with asbestos cord. This eliminates undue condensation of the distillate and variations in the final and total distillation times. The modified method was tested by 9 laboratories and, from their individual results, the coefficients of variation for the total time of distillation proved that the method gave excellent control of the final operation. The changes have been adopted as official first action.

Determination of Amprolium in Feeds: Collaborative Study

1979 ◽  
Vol 62 (3) ◽  
pp. 621-623
Author(s):  
E Jack Davis
Keyword(s):  
Aluminum Oxide ◽  
Collaborative Study ◽  
Official Method ◽  
Modified Method

Abstract The official final action method, 42.028-42.032, for determining amprolium in feeds was modified by a change in the preparation of aluminum oxide for chromatography. A premix containing 0.5% amprolium was collaboratively studied by the modified and the official methods. Compared with the modified method, 87.7% of the drug was recovered from the premix by using the official method. The modification makes possible the assay of premixes as well as finished feeds. The official final action method has been modified to incorporate this change.

Collaborative Study of a Rapid Method for Determining Aflatoxins in Cottonseed Products

1975 ◽  
Vol 58 (4) ◽  
pp. 746-753
Author(s):  
Walter A Pons
Keyword(s):  
Systematic Error ◽  
False Positive ◽  
Collaborative Study ◽  
Statistical Treatment ◽  
Official Method ◽  
Modified Method ◽  
Collaborative Studies ◽  
Coefficients Of Variation ◽  
Aoac Method ◽  
The Mean

Abstract Eleven laboratories collaboratively studied a modification of the official final action AOAC method, 26.048–26.056, for determining aflatoxins in cottonseed products. An aflatoxinnegative meal, 6 contaminated meals, 4 contaminated meats (kernels) samples, and 2 ammonia-inactivated meals were used. Mean a (latoxin values, μg/kg, ranged from 6 to 223 (B1), 2 to 44 (B2), and 7 to 266 (total: B1 + B2). Only one laboratory reported a false-positive for the negative meal. The mean coefficients of variation for B1, B2, and total were 28, 56, and 29%, respectively, for meals; 35, 54, and 37%, respectively, for meats; and 35, 58, and 38%, respectively, for ammoniated meals. Statistical treatment of data from triplicate sets of meals and meats showed evidence for systematic error between laboratories. Since the modified method is considerably faster than the official method and yields precision estimates consistent with previous AOAC collaborative studies on determining aflatoxins, the method has been adopted as official first action.

Analysis of Ergotamine Tartrate Suppository Preparations

1963 ◽  
Vol 46 (4) ◽  
pp. 634-636
Author(s):  
Thomas G Alexander
Keyword(s):  
Collaborative Study ◽  
Official Method ◽  
Modified Method ◽  
Ergotamine Tartrate

Abstract The official method for the analysis of ergotamine tartrate tablets has been adapted to the analysis of ergotamine tartrate suppository preparations. A collaborative study was conducted on this modified method. The method is recommended for adoption as official, first action.

Collaborative Study of a Microbiological Method for the Assay of Neomycin Sulfate in Feeds

1973 ◽  
Vol 56 (5) ◽  
pp. 1154-1160
Author(s):  
Billy Joe Williams
Keyword(s):  
Coefficient Of Variation ◽  
Reliable Method ◽  
Collaborative Study ◽  
Inhibition Zone ◽  
Official Method ◽  
Microbiological Method ◽  
Average Recovery ◽  
Modified Method ◽  
Neomycin B ◽  
Neomycin Sulfate

Abstract The official method for the microbiological assay of neomycin sulfate in feeds was modified by adding pH 8.0 Tris buffer to and deleting CaC12 from the base and seed agars. The modified method was collaboratively studied by 13 laboratories. Each laboratory performed single assays of 4 feed types at 4 medication levels over 4 months. The average recovery for all collaborators was 115.6% of theory with a coefficient of variation of 20.4%. Neither order of assay, feed type, nor ratio of neomycin B to C in the premix significantly affected the assays. Inhibition zone diameters were significantly larger for standard solutions prepared in 1 + 24 dilutions of inactivated feed extracts than for identical concentrations of standard in 1+49 dilutions of identical feed extracts. This study has been discontinued and a search for a more reliable method has been initiated.

Determination of Total Nitrogen in Fertilizers

1965 ◽  
Vol 48 (2) ◽  
pp. 401-406
Author(s):  
H A Davis ◽  
W E Urban
Keyword(s):  
Nickel Catalyst ◽  
Raney Nickel ◽  
Total Nitrogen ◽  
Official Method ◽  
Chromium Powder ◽  
Powder Method ◽  
Raney Nickel Catalyst ◽  
Catalyst Powder ◽  
Iron Chromium

Abstract Five methods, AOAC 2.037, 2.039, modified reduced iron, chromium powder, and Raney nickel catalyst powder for the determination of total nitrogen in fertilizers, were submitted to collaborators for study. Twelve laboratories participated and completed the work. No one method was “best.” The modified reduced iron, chromium powder, and Raney nickel catalyst powder methods gave essentially equal results, but the chromium powder method is favored for case of operation and time required. However, if considerable organic matter and nitrate are present in a sample, satisfactory results may not be obtained. The analyst should select the official method best suited to the makeup of the sample. It is recommended that the chromium powder method he adopted as official, first action, and that study be continued with the modified reduced iron and Raney nickel catalyst methods, including helpful proposals in developing a method that may be applicable to all fertilizers.

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