Comparison of Official AOAC Method and Indirect Atomic Absorption Spectroscopic Method for Determining Biuret in Fertilizers: Collaborative Study

1977 ◽  
Vol 60 (5) ◽  
pp. 1214-1219
Author(s):  
Luis F Corominas
Keyword(s):  
Atomic Absorption ◽  
Indirect Method ◽  
Spectroscopic Method ◽  
Collaborative Study ◽  
Matched Pairs ◽  
Alternative Method ◽  
Aoac Method ◽  
Aas Method

Abstract A collaborative study was carried out to compare the official first action method, 2.072—2.074, for determining biuret in urea and mixed fertilizers with the indirect atomic absorption spectrophotometric (AAS) method. Six urea samples (0.3–3.0% biuret) and 6 mixed fertilizer samples (0.1–0.6% biuret) were sent to 14 collaborators; results from 10 collaborators were received and evaluated. Results analyzed by the technique of closely matched pairs indicated the AAS indirect method was better for mixed fertilizer samples, but the 2 methods did not differ greatly for the urea samples. The indirect AAS method was adopted as official first action for determining biuret in urea and mixed fertilizers; the present AOAC method, with modifications, was retained as an alternative method for determining biuret in urea.

Comparison of AOAC and Atomic Absorption Spectrophotometry Methods for Determining Sodium in Fertilizers: Collaborative Study

1983 ◽  
Vol 66 (5) ◽  
pp. 1234-1241
Author(s):  
Luis F Corominas ◽  
Roberto A Navarro ◽  
Pedro Rojas ◽  
◽  
M Aihara ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Collaborative Study ◽  
Atomic Absorption Spectrophotometry ◽  
Sodium Content ◽  
Matched Pairs ◽  
High Potassium ◽  
Absorption Spectrophotometry ◽  
Low Sodium ◽  
Aoac Method ◽  
Aas Method

Abstract A collaborative study was carried out to compare AOAC method 2.147-2.150 for determining sodium in fertilizers with the atomic absorption spectrophotometric (AAS) method. Twelve synthetic NPK samples, 6 pairs of blind duplicates (0.06-8.5% Na), were sent to 22 collaborators; a total of 13 sets of results were received and evaluated by the modified matched pairs technique. The AAS method showed better performance in samples with low sodium content and high potassium content. The AAS method has been adopted official first action for determining sodium in fertilizers.

Atomic Absorption Spectroscopic Analysis of Aluminum Sulfate-Type Soil Acidifiers: Mini-Collaborative Study

1983 ◽  
Vol 66 (4) ◽  
pp. 946-948
Author(s):  
Ann Knutson ◽  
◽  
D Crawford ◽  
M Erickson ◽  
E Ingebrigtsen ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Atomic Absorption ◽  
Close Agreement ◽  
Aluminum Sulfate ◽  
Spectroscopic Analysis ◽  
Aluminum Content ◽  
Collaborative Study ◽  
Matched Pairs ◽  
Confidence Limits ◽  
Aoac Method

Abstract Commercial brand aluminum sulfate soil acidifiers were subjected to a simple water extraction and analyzed for aluminum content by applying the principles of AOAC method 8.023. The study was designed to follow Youden's procedure for closely matched pairs and yielded results in close agreement. Statistical analysis, using 98% confidence limits, showed no outliers among analyses or laboratories. The combined Sr value was 0.1702, indicating satisfactory within-laboratory precision. The method has been adopted official first action.

Atomic Absorption Spectrophotometric Method for Determination of Water-Soluble Copper in Water-Insoluble Copper Fungicides: CIPAC Collaborative Study. Comparison with Bathocuproine Method

1981 ◽  
Vol 64 (1) ◽  
pp. 75-78
Author(s):  
F Sánchez Rasero ◽  
◽  
P G Balayannis ◽  
H P Beyers ◽  
E Celma ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Collaborative Study ◽  
The United States ◽  
Atomic Absorption Spectrophotometry ◽  
Water Soluble ◽  
Absorption Spectrophotometry ◽  
Aas Method ◽  
Standard Deviations ◽  
The Difference

Abstract An atomic absorption spectrophotometric (AAS) method was collaboratively studied by 8 laboratories from Africa, the United States, Australia, and Europe. The samples were dispersed in deionized water. After centrifuging and filtering, the water-soluble copper in the filtrate was acidified and measured by atomic absorption spectrophotometry, in an airacetylene flame, at 324.7 nm. The results from 7 laboratories were satisfactory and no unfavorable comments were received. Repeatability standard deviations ranged from 0.005 to 0.023, and reproducibility standard deviations ranged from 0.012 to 0.062. When compared with the bathocuproine method, the difference in bias between both methods is not significant. They were both adopted as full CIPAC methods, with the bathocuproine method as the referee method. Both methods have been adopted official first action.

Comparison of Methods for Determining Sodium in Fertilizers

1981 ◽  
Vol 64 (3) ◽  
pp. 704-708
Author(s):  
Luis F Corominas ◽  
Víctor M Boy ◽  
Pedro Rojas
Keyword(s):  
Phosphate Rock ◽  
Collaborative Study ◽  
Ammonium Oxalate ◽  
Selective Electrode ◽  
Accuracy And Precision ◽  
Flame Emission ◽  
Aoac Method ◽  
Aoac Official ◽  
Aas Method

Abstract The AOAC official first action method, 2.147-2.150, for flame emission spectrophotometry (FES) determination of sodium in fertilizers was compared with the atomic absorption spectrophotometric (AAS) method and the sodium selective electrode (SSE) method. Ammonium oxalate, which was previously compared with water, H2SO4, HC1, and HNO3, was used to extract the sample for all 3 methods. Three synthetic NPK samples, 3 commercial samples (urea, normal superphosphate, and neutrophos), 1 phosphate rock, and 2 Magruder check samples were used for the study. Statistically significant differences were obtained in averages for most of the samples, but few differences were found in standard deviations. The AAS method showed the best accuracy and precision. Accuracy of the AOAC method is acceptable. The SSE method showed the highest deviations from the theoretical values. A collaborative study is recommended to compare the AOAC with the AAS method.

Isolation and Enumeration of Staphylococcus aureus: Review and Recommendations for Revision of AOAC Method

1971 ◽  
Vol 54 (3) ◽  
pp. 732-735
Author(s):  
E F Baer
Keyword(s):  
Staphylococcus Aureus ◽  
Present Method ◽  
Collaborative Study ◽  
Direct Plating ◽  
Alternative Method ◽  
Plating Method ◽  
Aoac Method ◽  
Aoac Official

Abstract The genesis of the present AOAC official first action method for isolation and enumeration of Staphylococcus is reviewed and information is supplied to support recommendations for revision of the method. It is recommended that the present method be revised by deleting instructions for preparation and use of Vogel and Johnson agar and substituting instructions for preparation and use of Baird-Parker medium. It is also recommended that a direct plating method be provided as an alternative method and that the required collaborative study of the alternative method be conducted. The recommendations have been accepted by the Association.

Atomic Absorption Spectrophotometric Determination of Chelated Iron in Iron Chelate Concentrates: Collaborative Study

1983 ◽  
Vol 66 (4) ◽  
pp. 952-955
Author(s):  
James R Silkey ◽  
◽  
S G Angell ◽  
K Bartunek ◽  
L W Clark ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Collaborative Study ◽  
Ferric Hydroxide ◽  
Disodium Edta ◽  
Iron Chelate ◽  
Iron Citrate ◽  
Coefficients Of Variation ◽  
Chelated Iron ◽  
Aas Method

Abstract An atomic absorption Spectrophotometric (AAS) method for determining chelated iron in iron chelate concentrates was collaboratively studied by 13 laboratories. Nonchelated iron was selectively precipitated as ferric hydroxide from an aqueous solution of the sample by adjusting to pH 8.5 with sodium hydroxide. A filtered portion of the sample solution was diluted with 0.5N HC1, and the iron was determined by AAS using standards containing disodium EDTA. Six pairs of iron chelate materials (12 samples) were analyzed and the average coefficients of variation were iron EDTA 3.52%, iron HEDTA 4.16%, iron DTPA 3.55%, iron EDDHA 3.52%, iron citrate 2.86%, and iron DPS 8.47%. The method has been adopted official first action.

Preliminary Comparison of Methods for Determining Sodium in Fertilizers

1980 ◽  
Vol 63 (3) ◽  
pp. 551-553
Author(s):  
Luis F Corominas ◽  
Victor M Boy ◽  
Manuel Guijosa
Keyword(s):  
Atomic Absorption ◽  
Experimental Work ◽  
Check Sample ◽  
Comparison Of Methods ◽  
Selective Electrode ◽  
Flame Emission ◽  
Aoac Method ◽  
Aoac Official ◽  
Aas Method

Abstract The AOAC official first action method 2.147–2.150 for the flame emission spectrophotometric (FES) determination of sodium in fertilizers was compared with the atomic absorption spectrophotometric (AAS) method and the sodium selective electrode (SSE) method. Two synthetic NPK samples, 3 commercial samples (urea, DAP, and superphosphate), 2 Magruder NPK check samples, and one Magruder muriate check sample were used for the study. Statistically significant differences were obtained in both averages and standard deviations for all samples. In general, the precision for all methods was acceptable; the AAS method seems to be the more accurate; the AOAC method needs to be revised; and the SSE method has the tendency to give higher values. Additional experimental work is necessary to define which method is the most convenient.

Atomic Absorption Spectrophotometric Determination of Mercury in Mercury≃Containing Drugs: Collaborative Study

1983 ◽  
Vol 66 (5) ◽  
pp. 1203-1206
Author(s):  
Walter Holak ◽  
◽  
R Baltz ◽  
L Elliott ◽  
E McGary ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Spectrophotometric Determination ◽  
Collaborative Study ◽  
Ophthalmic Solution ◽  
Mean Value ◽  
Antiseptic Solution ◽  
Aas Method ◽  
Low Levels

Abstract An atomic absorption spectrophotometric (AAS) method applicable to a wide variety of mercurycontaining drugs has been developed and subjected to a collaborative study. Samples were digested with a water-HCl-HN03 (4 + 3 + 1) mixture, and the mercury was determined in solution by AAS. High levels of mercury were measured with a conventional air-acetylene flame, whereas low levels were measured by the flameless technique. Each of 7 collaborators received duplicate synthetic samples of a tincture, an ophthalmic solution, and an antiseptic solution, and duplicate commercial samples of an ointment and an injectable. The overall mean value found by collaborators for mercury in these samples was 100.13%. The corresponding overall repeatability SD (CV, %) and reproducibility SD (CV, %) values were 2.18 (2.18) and 3.38 (3.38), respectively. The proposed AAS method has been adopted official first action.

Graphite Furnace Atomic Absorption Spectrophotometric Determination of 4-Hydroxy-3-Nitrobenzene Arsonic Acid in Finished Animal Feed: Collaborative Study

1986 ◽  
Vol 69 (5) ◽  
pp. 838-843
Author(s):  
Glenn M George ◽  
Larry J Fra ◽  
◽  
C F Aten ◽  
J Bestianich ◽  
...  
Keyword(s):  
Atomic Absorption ◽  
Animal Feed ◽  
Graphite Furnace ◽  
Collaborative Study ◽  
Method Performance ◽  
Relative Standard ◽  
Graphite Furnace Atomic Absorption ◽  
Aas Method ◽  
Arsonic Acid

Abstract Eight laboratories participated in a collaborative study of an atomic absorption spectrophotometric (AAS) method for determination of 4- hydroxy-3-nitrobenzene arsonic acid (roxarsone), which is administered in animal feed at levels of 25-50 ppm as a growth stimulant. The drug is extracted from feed by using aqueous 1% ammonium carbonate solution. Undissolved feed particles are allowed to settle, and then a diluted aliquot of the feed extract is analyzed for total arsenic by AAS using a graphite furnace for sample atomization. Collaborators performed single analyses on 18 samples which were randomly numbered blind duplicate pairs of a complete poultry ration fortified with roxarsone at concentrations from 22.5 to 55.0 ppm. Statistical evaluation of the collaborative data showed satisfactory method performance. Overall mean recovery of roxarsone was 100.4% and the overall relative standard deviation was 6.2%. The method has been adopted official first action.

Acid Digestion, Hydride Evolution Atomic Absorption Spectrophotometric Method for Determining Arsenic and Selenium in Foods: Collaborative Study. Part I

1977 ◽  
Vol 60 (6) ◽  
pp. 1414-1433
Author(s):  
Milan Ihnat ◽  
Hanford J Miller
Keyword(s):  
Atomic Absorption ◽  
Graphite Furnace ◽  
Collaborative Study ◽  
Milk Powder ◽  
Skim Milk ◽  
Hydride Generation ◽  
Skim Milk Powder ◽  
Custom Made ◽  
Graphite Furnace Aas ◽  
Aas Method

Abstract The hydride evolution atomic absorption spectrophotometric (AAS) method for determining As and Se in foods developed and evaluated by the Food and Drug Administration and Agriculture Canada laboratories was subjected to collaborative study. Twenty-four laboratories provided results for As and 23 provided results for Se levels in 13 different samples consisting of tuna, swordfish, flounder, oyster, liver, flour, skim milk powder, spinach, kale, and apple containing natural levels of As and Se in the ranges 0–15,000 and 0–4000 ng/g, respectively. Reference materials formed a substantial segment of samples, and a number of other laboratories using fluorometry, colorimetry, neutron activation, spark source mass spectrometry, and graphite furnace AAS provided confirmative reference values for the remaining samples. A variety of hydride generation instruments were used, ranging from commercially available devices to semiautomated and fully automated custom-made instruments. Although the accuracy of the method was fairly good, between-laboratory and between-determination (hydride evolution AAS measurement) precisions were not favorable. The main advantage of the hydride AAS method is the rapidity of the determinative step.

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