Gamma-Ray Spectroscopic Determination of Iodine-131 and Cesium-137 in Foods: Two Collaborative Studies

1989 ◽  
Vol 72 (4) ◽  
pp. 667-669
Author(s):  
Edmond J Baratta ◽  
David G Easterly
Keyword(s):  
Gamma Ray ◽  
Food Sample ◽  
Spectroscopic Determination ◽  
Collaborative Studies ◽  
Cesium 137 ◽  
Aoac Method ◽  
Iodine 131 ◽  
The Mean ◽  
Standard Deviations

Abstract The AOAC method for iodine-131, cesium-137, and barium-140 in milk by gamma-ray spectroscopy (48.025-48.029) was extended to include other foods for the radionuclides iodine-131 and cesium-137. Two collaborative studies were performed to validate this extension. In the first study, a food sample containing 119 pCi ,3,I/kg and 53 pCi 137Cs/kg was sent to each of 45 laboratories for triplicate analyses. For 25 responses, the mean of the reported values was 123.8 pCi/kg for iodine-131, and for 27 responses, the mean was 53.4 pCi/kg for cesium-137. Repeatability (within-laboratory) standard deviations (sr) for iodine-131 and cesium-137 were 4.6 and 3.7 pCi/kg, respectively. Reproducibility (among-laboratories) standard deviations (sR) for iodine-131 and cesium-137 were 12.1 and 6.0 pCi/kg, respectively. In the second study, a food sample containing 25 pCi 13,I/kg and 27 pCi 137Cs/kg was sent to each of 54 laboratories for triplicate analyses. For 21 responses, the mean of the reported values was 25.0 pCi/kg for iodine-131, and for 19 responses, the mean was 28.9 pCi/kg for cesium-137. sr Values were 4.0 and 1.6 pCi/kg for iodine-131 and cesium-137, respectively, and SR values were 5.0 and 2.8 pCi/kg, respectively. The method extension was adopted official first action.

Gamma Spectroscopic Determination of Cesium-137 in Milk, Using Simultaneous Equations: Collaborative Study

1973 ◽  
Vol 56 (1) ◽  
pp. 204-207
Author(s):  
Edmond J Baratta ◽  
F E Knowles
Keyword(s):  
Sodium Iodide ◽  
Spectroscopic Method ◽  
Collaborative Study ◽  
Simultaneous Equations ◽  
Spectroscopic Determination ◽  
Low Level ◽  
Cesium 137 ◽  
Iodine 131

Abstract A gamma spectroscopic method, using a sodium iodide (thallium-activated) crystal, was evaluated by 25 collaborators for the determination of cesium-137 in milk. Overall average recoveries of 295±18.1 and 53±5.3 pCi/L were obtained for samples containing 305 and 52 pCi/L, respectively. These samples also contained iodine-131 and barium-140, which did not interfere with the analyses. The slight bias on the low side and the greater dispersion of results for the low level sample were not considered serious. The method has been adopted as official first action.

Chemical Determination of Niacinamide in Multivitamin Preparations

1968 ◽  
Vol 51 (4) ◽  
pp. 828-834
Author(s):  
Omer Pelletier
Keyword(s):  
Coefficient Of Variation ◽  
Microbiological Method ◽  
Chemical Methods ◽  
Mean Values ◽  
The Third ◽  
Collaborative Studies ◽  
Chemical Determination ◽  
Aoac Method ◽  
The Mean

Abstract The AOAC method and the Pelletier and Campbell method for the assay of niacinamide in multivitamin preparations were compared in two collaborative studies. In the first study, three multivitamin sirup preparations were analyzed by six laboratories; the proposed method gave higher results for two preparations but lower results for the third. In the second study, four types of multivitamin preparations were analyzed; twelve laboratories reported on the chemical methods and three laboratories on the microbiological method. There was no difference in the mean values for two types of samples, but one sample of multivitamin tablets yielded mean values about 5% lower by the proposed method, suggesting the presence of a trace of niacin; with a multivitamin and mineral sirup the proposed method gave values about 6% higher than the AOAC method and 3% lower than the microbiological assay. The coefficient of variation for any sample in any laboratory by the AOAC method was about 14% in the first study and 1 1% in the second study; by the proposed method it was 4 and 9% in the same respective studies. It is recommended that the present AOAC method be modified by adjusting the pH of sample hydrolysates in the range of 2.5—4.5 instead of 7—9 to reduce the absorhance of the blanks, and that the method of Pelletier and Campbell be adopted as official, first action.

Quantitative Determination of 1-131, Cs-137, and Ba-140 in Milk: Collaborative Studies

1982 ◽  
Vol 65 (5) ◽  
pp. 1039-1043
Author(s):  
Frederick G D Shuman ◽  
David G Easterly ◽  
Edmond J Baratta
Keyword(s):  
High Activity ◽  
Gamma Ray ◽  
Collaborative Study ◽  
Official Method ◽  
Collaborative Studies ◽  
Coefficients Of Variation ◽  
The Mean ◽  
Method Bias ◽  
Low Activity

Abstract The official method for Cs-137 in milk by gamma-ray spectroscopy was extended to include 1-131 and Ba- 140. A collaborative study was performed on this method applied to 1-131 concentration in cow's milk; the original collaborative study of the method including all 3 nuclides was reviewed. In the 1-131 study, 1 aliquot of a milk sample containing 82 pCi/L was sent to each of 60 laboratories for triplicate analyses. From 40 responses, the mean of the reported values was 81.6 pCi/L, indicating a method bias below the 5% statistical detectability limit. Within- and between-laboratory coefficients of variation (CVs) were 7 and 8%, respectively. In the 3-nuclide study, 2 samples were sent to 25 laboratories for triplicate analyses; one sample contained 633,305, and 515 pCi/L, respectively, of 1-131, Cs-137, and Ba-140 and the other contained 98,52, and 72 pCi/L. For the high-activity sample, within-laboratory CVs were 4-5% for the 3 nuclides and between-laboratory CVs were 4-7%. For the low-activity sample, the corresponding results were 6-9% and 8-16%. The method bias was statistically significant at 95% confidence only for Cs-137 in the high-activity sample; reported results were 3% below the known concentration. The extended method was adopted official first action.

Collaborative Study of the Determination of Phosphorus in Gelatin, Dessert Preparations, and Mixes

1972 ◽  
Vol 55 (3) ◽  
pp. 581-582
Author(s):  
Roger G Burkepile
Keyword(s):  
Collaborative Study ◽  
Official Method ◽  
Standard Samples ◽  
Preliminary Work ◽  
Aoac Method ◽  
Standard Deviations

Abstract A collaborative study of the proposed method for phosphorus in gelatin, dessert preparations, and mixes has been conducted. The present AOAC method for phosphorus in fertilizers, 2.023–2.025(a), was modified for this study. Preliminary work by the Associate Referee involving 4 phosphorus standard samples compared the proposed method with the official final action AOAC method for gelatin, 23.004. Additionally, phosphorus standard spikes in gelatin at the 1 and 10 mg P2O5, levels were determined by the proposed method. The proposed method is faster and more sensitive than the official method and is as accurate. Five collaborators and the Associate Referee analyzed 4 prepared samples containing various levels of phosphorus by the proposed method. The standard deviations varied from 0.005 for a 225 Bloom gelatin containing an average of 0.273% P2O5 to 0.016 for a strawberry-flavored commercial gelatin with added lecithin containing an average of 0.110% P2O5. The proposed method has been adopted as official first action to replace 23.004, which was repealed, official first action.

scholarly journals A Simplified Modification of the AOAC Official Method for Determination of Total Dietary Fiber Using Newly Developed Enzymes: Preliminary Interlaboratory Study

2007 ◽  
Vol 90 (1) ◽  
pp. 225-237 ◽  
Author(s):  
Kenichiro Kanaya ◽  
Shusaku Tada ◽  
Bunpei Mori ◽  
Rie Takahashi ◽  
Sachie Ikegami ◽  
...  
Keyword(s):  
Dietary Fiber ◽  
Enzymatic Digestion ◽  
Interlaboratory Study ◽  
Total Dietary Fiber ◽  
Stabilizing Agents ◽  
Modified Method ◽  
Relative Standard ◽  
Aoac Method ◽  
Standard Deviations

Abstract A preliminary interlaboratory study was conducted to evaluate the validity of the modified AOAC method for determination of total dietary fiber by Tada and Innami, in which the 3-step enzymatic digestion process in AOAC Method 991.43 is modified to a 2-step process without pH adjustment. Total dietary fiber contents in 8 representative foodstuffs were measured using both the original AOAC Method 991.43 and the modified method in 6 research facilities in Japan. Repeatability relative standard deviations, reproducibility relative standard deviations, and Horwitz ratio values from the modified method were equivalent to those from AOAC Method 991.43, except in the rice sample. However, this exceptional case shown in the modified method was entirely dissolved by the addition of α-amylase stabilizing agents. The modified method, which shortens the process of enzymatic digestion from 3 to 2 steps and in which only reaction temperature is adjusted under the same pH, was found not only to give accurate values comparable to the original method, but also to substantially reduce the labor required by the laboratory staff in the process of routine analysis. This study revealed that the validity of the modified method was further ensured by adding α-amylase stabilizing agents to the reaction system.

Determination of Protein Nitrogen in Plants

1977 ◽  
Vol 60 (3) ◽  
pp. 590-593 ◽  
Author(s):  
T Powell Gaines
Keyword(s):  
Acetic Acid ◽  
Plant Tissue ◽  
Nonprotein Nitrogen ◽  
Protein Nitrogen ◽  
Aoac Method ◽  
The Mean

Abstract A method is described for determining protein nitrogen (PN) in plants. Plant tissue extracted with 0.5% acetic acid to remove nonprotein nitrogen (NPN) prior to Kjeldahl analysis gave results very close to true PN, whereas AOAC crude PN method 2.049 gave results much too high. True PN was determined as the mean of 3 independently derived values and was used as the basis for comparing the proposed PN method with AOAC method 2.049. Failure of the AOAC method to differentiate between NPN and/or inorganic ammoniacal N and actual PN causes values derived from this method to be too high when it was used to determine PN in plants.

scholarly journals Determination of Atrazine in Water by Magnetic Particle Immunoassay: Collaborative Study

1996 ◽  
Vol 79 (2) ◽  
pp. 529-537 ◽  
Author(s):  
Mary C Hayes ◽  
Scott W Jourdan ◽  
David P Herzog ◽  
P Barnes ◽  
C Charan ◽  
...  
Keyword(s):  
Detection Limit ◽  
Water Sample ◽  
Magnetic Particle ◽  
Collaborative Study ◽  
Study Data ◽  
Collaborative Studies ◽  
Enzyme Conjugate ◽  
Repeatability And Reproducibility ◽  
The Mean

Abstract A collaborative study was performed to determine mean recovery and precision for analysis of atrazine in drinking and surface waters by immunoassay. The study design was based on the blind duplicate test plan for collaborative studies. Three blank waters (municipal drinking water, well water, and surface water) were spiked at 3 atrazine levels. Two water samples with naturally incurred atrazine loads were also spiked with atrazine at 3 levels. In the enzyme-linked immunoassay method, the water sample is mixed with a pesticide–enzyme conjugate and added to paramagnetic particles with triazine-specific antibodies attached. After separation of antibody-bound atrazine and atrazine–enzyme conjugate from free components, the bound enzyme conjugate catalyzes a reaction producing a colored end product. The color developed is inversely proportional to the original concentration of atrazine in the water sample. Fourteen laboratories participated in the collaborative study. Data were analyzed for repeatability and reproducibility, and average recoveries at the spike levels were calculated. Over the concentration range tested, the mean recovery of atrazine spiked into blank and pesticide-contaminated waters was 104%. Overall RSDRaveraged about 40% for atrazine concentrations near the method detection limit (0.05 μg/L) and about 15% at concentrations above 5 times the detection limit (0.25 μg/L). Corresponding single-analyst RSDr values were 24 and 10%. Recovery and precision for the 3 blank water matrixes and the waters that had been naturally contaminated with atrazine showed no significant differences. The magnetic particle immunoassay

Proton Magnetic Resonance Spectroscopic Determination of Disulfiram: Collaborative Study

1978 ◽  
Vol 61 (1) ◽  
pp. 55-59
Author(s):  
Eric B Sheinin ◽  
Walter R Benson
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Drug Product ◽  
Spectroscopic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Spectroscopic Determination ◽  
Standard Deviations ◽  
Bulk Drug

Abstract A proton magnetic resonance spectroscopic method for determining disulfiram in the bulk drug product and in the formulated material was collaboratively studied. The method depends on the use of chloroform-d as a solvent and hexamethylcyclotrisiloxane as the internal standard. No interference from tablet excipients was observed. The method is rapid and specific. Eighteen laboratories analyzed duplicate samples of a bulk drug product, a 250 mg tablet composite, and a 500 mg tablet composite. The average per cent results and standard deviations were 99.7±1.4, 100.9±2.0, and 99.9±2.2, respectively.

Iodine-131 in Foods

1964 ◽  
Vol 47 (4) ◽  
pp. 681-684
Author(s):  
Richard J Velten
Keyword(s):  
Collaborative Studies ◽  
Two Samples ◽  
Iodine 131

Abstract Two collaborative studies have been conducted on the determination of 1-131 in milk. In the first study, eight collaborators analyzed four samples ranging from 58 to 227 pc/L 1-131, but results were inconclusive. In the second study, 15 collaborators reported results for two samples. Results were much better. A third study is planned, on the basis of which a method will be proposed for adoption.

Determination of the Iodine Value of Oils and Fats: Summary of Collaborative Study

1994 ◽  
Vol 77 (3) ◽  
pp. 674-676 ◽  
Author(s):  
David Firestone
Keyword(s):  
Acetic Acid ◽  
Iodine Value ◽  
Collaborative Study ◽  
Solvent Mixture ◽  
Acid Mixture ◽  
Collaborative Studies ◽  
Wide Range ◽  
Aoac Method ◽  
Iodine Values

Abstract Two collaborative studies were conducted using the Wijs method for determining the iodine value in a wide range of vegetable and animal oils and fats. The results obtained when using carbon tetrachlo-ride were compared to those obtained when using a substitute solvent mixture of cyclohexane and glacial acetic acid. The values reported for the iodine values indicate that the cyclohexane and acetic acid mixture can be used in place of carbon tetrachloride without loss of precision. The method has been adopted first action by AOAC INTERNATIONAL as an IUPAC/AOCS/AOAC method.

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