Collaborative Study of an Automated Method for Phosphorus in Fertilizers

1972 ◽  
Vol 55 (5) ◽  
pp. 979-983
Author(s):  
Frank J Johnson
Keyword(s):  
Collaborative Study ◽  
Available Phosphorus ◽  
Official Method ◽  
Matched Pairs ◽  
F Test ◽  
Automated Method

Abstract A collaborative study was made of an automated method for total and direct available phosphorus (P2O5) in comparison with the official gravimetric quimociac method, 2.023–2.025. Eight laboratories participated in the analysis of the 13 sample solutions, and the results were evaluated by the technique of closely matched pairs. The fc-test showed no difference in the means of the results of the 2 methods. The estimates of the random, systematic, and total errors of the automated method all differed significantly from those of the official method when evaluated by the F-test. Further study of the automated method for P2O5 in fertilizers is recommended.

Collaborative Study of an Automated Method for the Determination of Total and Direct Available P2O5 in Fertilizers

1973 ◽  
Vol 56 (5) ◽  
pp. 1084-1086
Author(s):  
Frank J Johnson
Keyword(s):  
Collaborative Study ◽  
T Test ◽  
Official Method ◽  
Matched Pairs ◽  
F Test ◽  
Automated Method

Abstract In a collaborative study, an automated method for the determination of total and direct available P2O5 was compared with the official gravimetric quinolinium molybdophosphate method, 2.023–2.025. Nine laboratories participated in the analysis of the 12 sample solutions, and the results were evaluated by the technique of closely matched pairs. The t-test showed no difference in the means of the results of the 2 methods. The estimates of the random, systematic, and total errors of the automated method all differed significantly from those of the official method when evaluated by the F-test. Further study of the automated method for P2O5 in fertilizers is not recommended.

Automated Determination of Phosphorus in Fertilizers Collaborative Study

1978 ◽  
Vol 61 (3) ◽  
pp. 533-536
Author(s):  
Frank J Johnson
Keyword(s):  
Collaborative Study ◽  
Available Phosphorus ◽  
Matched Pairs ◽  
Automated Method ◽  
Complete Sets ◽  
Automated Determination

Abstract An automated method for determining total and direct available P2O5 in fertilizers was compared to the official final action gravimetric quinolinium molybdophosphate and spectrophotometric molybdovanadate methods in a collaborative study. Ten samples were sent to 10 collaborators for analysis. Eight complete sets of data were returned, and the ninth collaborator returned data for direct available phosphorus by the automated method only. The data were statistically analyzed by the technique of closely matched pairs. No significant overall difference was found between methods or among collaborators. The automated method has been adopted as official first action for phosphorus.

Collaborative Study of the Automated Method for K2O in Fertilizers

1971 ◽  
Vol 54 (3) ◽  
pp. 646-650
Author(s):  
Larry G Hambleton
Keyword(s):  
Primary Standard ◽  
Collaborative Study ◽  
Potassium Nitrate ◽  
Matched Pairs ◽  
Automated Method ◽  
Standard Deviations ◽  
Complete Sets

Abstract The automated method for K2O in fertilizers was studied again this year. The results from the automated method are compared to those obtained by the official STPB method, 2.090, for 10 typical fertilizer samples and a potassium nitrate primary standard. Nine complete sets of data are evaluated by the technique of closely matched pairs. The data show no difference between the different models of flame photometers. The means and standard deviations from the automated method compare favorably to those received with the official STPB method. The automated method for K2O in fertilizers has been adopted official first action.

Collaborative Study of the Quantitative Gas-Liquid Chromatographic Determination of Fusel Oil and Other Components in Whisky

1972 ◽  
Vol 55 (3) ◽  
pp. 549-556
Author(s):  
J H Kahn ◽  
E T Blessinger
Keyword(s):  
Ethyl Acetate ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Official Method ◽  
Fusel Oil ◽  
Fusel Alcohols ◽  
Aoac Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Fifteen chemists participated in a collaborative study for the quantitative pas-liquid chromatographic determination of the individual fusel alcohols and ethyl acetate in whisky. Two levels of congeners represented by 4 coded samples of whisky were analyzed by using t h e proposed method, employing a glycerol-1,2,6-hexanetriol column, and the official AOAC method, 9.063-9.065. Since isobutyl and the atnyl alcohols comprise by far the greatest part of fusel oil, their determination is of major importance to the total fusel oil content . Statistical analyses show that the proposed method is superior to the AOAC method for the determination of these alcohols, whereas the official method is superior for the determination of ethyl acetate and n-propyl alcohol. In general, collaborators employing modern instrumentation preferred the proposed method over the AOAC method. The former method also separates and permits the quantitative measurement of active amyl and isoamyl alcohols. The proposed method has been adopted as official first action as an alternative to 9.063–9.065 for the determination of higher alcohols and ethyl acetate in whisky.

scholarly journals Determination of Fish Flesh Content in Frozen Coated Fish Products (Modification of AOAC Official Method 971.13): Collaborative Study

1997 ◽  
Vol 80 (6) ◽  
pp. 1235-1271 ◽  
Author(s):  
Jane E Fox Dobson ◽  
Foster D McClure ◽  
Alvin P Rainosek ◽  
K Dashiell ◽  
J Fox Dobson ◽  
...  
Keyword(s):  
Raw Materials ◽  
Collaborative Study ◽  
Processing System ◽  
Test Sample ◽  
Official Method ◽  
Fish Products ◽  
Fish Flesh ◽  
Aoac Official ◽  
Fully Cooked ◽  
Aoac Official Method

Abstract An intralaboratory1collaborative study evaluated a modified version of AOAC Official Method 971.13 for determining the fish flesh content (FFC) in frozen coated fish products by comparing it with the on-line method. Eleven collaborators analyzed 36 products (a total of 6336 test samples). Each product targeted one of 4 percent fish flesh (PFF) levels (35,50,65, and 80). Products were manufactured from one of 3 raw materials (fillet blocks, minced blocks, and natural fillets) and processed in one of 4 forms (sticks, portions, formed portions, and fillets) and one of 4 styles (raw breaded, batter-dipped, precooked, and fully cooked). Each “official” test sample was tracked through the processing system and weighed (1) before battering and/or breading and, depending on product style, before frying; and (2) after battering and/or breading and, depending on product style, after frying; so that it served as its own control.

scholarly journals Comparison of Babcock and Ether Extraction Methods for Determination of Fat Content of Cream: Collaborative Study

1996 ◽  
Vol 79 (4) ◽  
pp. 907-916 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Extraction Method ◽  
Collaborative Study ◽  
Extraction Methods ◽  
Fat Content ◽  
Official Method ◽  
Ether Extraction ◽  
Aoac Official ◽  
The Difference ◽  
Aoac Official Method

Abstract A modified Mojonnier ether extraction method for determination of the fat content of cream was developed based on the method for milk (AOAC Official Method 989.05). The cream Babcock method (AOAC Official Method 920.111 B-C) was modified to harmonize with the milk Babcock method (AOAC Official Method 989.04) and to clarify procedural details. Using the AOAC collaborative study format, 10 laboratories tested 9 pairs of blind duplicate heat-treated cream samples with a fat range of 30-45% using both methods. The statistical performance (invalid and outlier data removed) was as follows: mean % fat = 37.932, sr = 0.125, sR = 0.151, RSDr = 0.330, RSDR = 0.398, r = 0.354, and R = 0.427 for the ether extraction method. For the Babcock method, mean % fat = 38.209, sr = 0.209, SR = 0.272, RSDr = 0.548, RSDR = 0.712, r = 0.592, and R = 0.769. Average test results for fat from the Babcock method were 0.277% (absolute fat) greater than for the Mojonnier ether extraction method. The difference between methods, as a percentage of the average fat content of the samples, was 0.73%. This agrees with differences observed between the 2 methods for milk when 10 to 17 laboratories tested 7 milk samples in blind duplicate at bimonthly intervals over a 4-year period (average difference 0.029% fat, 0.78% as a percentage of average fat content). The Mojonnier ether extraction and Babcock methods for fat in cream have been adopted by AOAC INTERNATIONAL. The new Babcock method replaced the AOAC Official Method 920.111 B-C.

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.

Collaborative Study of Turbidimetric Microbiological Assay of Monensin in Chicken Rations

1977 ◽  
Vol 60 (1) ◽  
pp. 179-182
Author(s):  
H Latham Breunig ◽  
Robert E Scroggs ◽  
Lealon V Tonkinson ◽  
Henry Bikin
Keyword(s):  
Experimental Design ◽  
Collaborative Study ◽  
Microbiological Assay ◽  
Assay Method ◽  
Turbidimetric Method ◽  
Automated Method ◽  
Relative Standard ◽  
Significant Difference ◽  
Feed Form ◽  
Automated Methods

Abstract A turbidimetric microbiological assay method for monensin in chicken rations was submitted in a modified form to 8 collaborating laboratories along with randomized and coded samples. Three laboratories used the manual method and 5 used the automated method. Other factors in the experimental design were ration types (broiler starter, broiler finisher, and pullet grower), feed form (meal vs. pellets), and potency level (90 and 110 g/ton) for one ration. Average recoveries for the ration types over all laboratories and feed forms were 87.7—93.13% of label, while mean recoveries in 2 feed forms were 91.7% for meal and 87.6% for pellets. Average recoveries in the 8 laboratories ranged from 84.6 to 106.64% of label for 90 g/ton rations and 87.1 to 106.6% for 110 g/ton rations. There was no significant difference between the manual and the automated methods. The collaborators’ assays were uniform with respect to within-laboratory variation. Relative standard deviations ranged from 4.51 to 10.76% with a median of 6.04%. Agreement with the plate assay is quite good. The turbidimetric method for monensin has been adopted as official first action.

Determination of Maleic Hydrazide Residues in Tobacco and Vegetables

1973 ◽  
Vol 56 (5) ◽  
pp. 1164-1172
Author(s):  
Milan Ihnat ◽  
Robert J Westerby ◽  
Israel Hoffman
Keyword(s):  
Standard Deviation ◽  
Present Method ◽  
Maleic Hydrazide ◽  
Collaborative Study ◽  
Official Method ◽  
Sample Weight ◽  
Relative Standard ◽  
The Mean ◽  
Pipe Tobacco

Abstract The distillation-spectrophotometric method of Hoffman for determining maleic hydrazide has been modified to include a double distillation and was applied to the determination of 1–30 ppm maleic hydrazide residues in tobacco and vegetables. Recoveries of 1–23 μg added maleic hydrazide were independent of weight of maleic hydrazide, but did depend on sample and sample weight. The following recoveries were obtained from 0.5 g sample: pipe tobacco, 84%; commercially dehydrated potato, 83%; cigar tobacco, 81%; dried potato, 76%; fluecured tobacco, 73%; dried carrot, 71%. In the absence of sample, the recovery was 82%. When appropriate standard curves were used, maleic hydrazide levels determined in tobacco samples were essentially independent of sample weight in the range 0.1–3 g. The mean relative standard deviation for a variety of field-treated and fortified tobacco samples containing 1–28 ppm maleic hydrazide was 3%. The precision and sensitivity of this procedure seem to be substantial improvements over official method 29.111–29.117. It is recommended that the present method be subjected to a collaborative study.

Methods for Determining Carbohydrates, Hydroxymethylfurfural, and Proline in Honey: Collaborative Study

1979 ◽  
Vol 62 (3) ◽  
pp. 515-526
Author(s):  
Jonathan W White
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Collaborative Study ◽  
Official Method ◽  
Selective Absorption ◽  
Absorption Method

Abstract A modification of the official selective absorption method for honey carbohydrates, 31.124–31.133, was studied collaboratively; the determinations of sucrose, total monosaccharides, disaccharides, and higher sugars by this procedure were satisfactory and were adopted by the AOAC. High pressure liquid chromatography of glucose, fructose, and sucrose in honey showed better precision than the modified official method and gave concordant results; it was also adopted. Two methods for hydroxymethylfurfural do not qualify. A method for proline was also adopted.

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