Collaborative Study of an Electrometric Method for Determination of pH of Cacao Products

1970 ◽  
Vol 53 (3) ◽  
pp. 474-475
Author(s):  
John L Iverson
Keyword(s):  
Collaborative Study ◽  
Hot Water ◽  
Electrometric Method ◽  
Good Agreement

Abstract The sample is dispersed in hot water, filtered, and cooled and the pH of the filtrate is measured with a pH meter standardized against standard buffers. Results of a collaborative study show good agreement between samples and laboratories. It is recommended that the method be adopted as official first action.

Determination of Sevin Insecticide Residues in Fruits and Vegetables

1964 ◽  
Vol 47 (2) ◽  
pp. 283-286
Author(s):  
D P Johnson
Keyword(s):  
Fruits And Vegetables ◽  
Collaborative Study ◽  
Colorimetric Determination ◽  
Average Recovery ◽  
Insecticide Residues ◽  
Chromogenic Agent ◽  
Hydrolysis Of ◽  
Concentration Levels ◽  
Good Agreement

Abstract Collaborative study of a method for Sevin insecticide residues was repeated with apples and lettuce as test crops. The method is based on alkaline hydrolysis of Sevin and colorimetric determination of the resulting 1-naphthol with p-nitrobenzenediazonium fluoborate as chromogenic agent. Data from 5 collaborators were in good agreement with an average recovery of 87.8% at 2 concentration levels. It is recommended that the method be adopted as official, first action.

Collaborative Study of Two New Methods for the Determination of Phosphorus in Fruits and Fruit Products

1970 ◽  
Vol 53 (3) ◽  
pp. 575-578
Author(s):  
Ben Estrin ◽  
Frederick E Boland
Keyword(s):  
Aqueous Solution ◽  
Satisfactory Agreement ◽  
Collaborative Study ◽  
Volumetric Method ◽  
Acid Solutions ◽  
Dilute Acid ◽  
New Methods ◽  
Molybdate Method ◽  
Good Agreement

Abstract A collaborative study was conducted to compare a spectrophotometric molybdovanadate method and the official gravimetric quinoline molybdate fertilizer method 2.025(b), slightly modified, with the official volumetric method 20.032. Six collaborating laboratories analyzed dilute acid solutions of the ash of 5 different kinds of fruit products and an aqueous solution containing only KH2PO4 by each of the 3 methods. Satisfactory agreement between laboratories and good agreement between methods were obtained. From the results of this collaborative study it appears that the quinoline molybdate and the molybdovanadate methods are more accurate and precise than the official volumetric method. It is recommended that both the spectrophotometric molybdovanadate method and the gravimetric quinoline molybdate method for the determination of phosphorus in fruits and fruit products be adopted as official first action.

Collaborative Study of a Method for the Determination of Trimethylamine Nitrogen in Fish

1971 ◽  
Vol 54 (3) ◽  
pp. 725-727 ◽  
Author(s):  
Frederick E Boland ◽  
Dorothy D Paige
Keyword(s):  
Statistical Analysis ◽  
Collaborative Study ◽  
Standard Solution ◽  
Good Agreement

Abstract Dyer’s method for the determination of trimethylamine was collaboratively studied. Six samples of fish extract and one standard solution were sent to each of 9 collaborators. The results from one laboratory differed significantly from the remainder and were not included in the statistical analysis. The results from the remainder of the collaborators were generally in good agreement. Results clearly differentiate between the acceptable and decomposed samples which were used in this study. The method for determining trimethylamine nitrogen in fish has been adopted as official first action.

Collaborative Study of a Joint AOAC-OICC Method for the Determination of Ash in Cacao Products

1972 ◽  
Vol 55 (5) ◽  
pp. 1027-1030 ◽  
Author(s):  
John L Iverson
Keyword(s):  
Collaborative Study ◽  
Constant Weight ◽  
Aoac Method ◽  
International Collaborative ◽  
Infrared Lamps ◽  
Good Agreement ◽  
International Collaborative Study

Abstract A joint AOAC-OICC method for determining ash in cacao products, combining the best features of AOAC method 13.003 and OICC method 4a-E/1952 and with an ashing temperature of 600°C, has been developed. The results from an international collaborative study with 12 collaborators were in good agreement. The preferred method is pre-ashing of the sample under infrared lamps, followed by overnight ashing, thus eliminating reweighing at intervals to arrive at constant weight. The method for determining ash in cacao products has been adopted as official first action.

Collaborative Study of Infrared Methods for Phorate in Formulations

1964 ◽  
Vol 47 (2) ◽  
pp. 245-247
Author(s):  
N Kobekt Pasarela
Keyword(s):  
Collaborative Study ◽  
Infrared Method ◽  
Infrared Methods ◽  
Good Agreement

Abstract An infrared method for the determination of phorate in 5% and 10% granules was studied by 10 collaborators. In the method, the formulation is eluted from the carrier with acetonitrile, the solvent is removed by evaporation, and the residue is dissolved in cyclohexane. The absorbance of the solution is measured at 8.32 μ and the phorate content is determined by comparison with a sample of purified phorate treated in the same manner. Results show good agreement between replicates and laboratories. It is recommended that the method for phorate in granular formulations be adopted as official, first action.

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.

scholarly journals Determination of Choline in Infant Formula by Ion Chromatography

1999 ◽  
Vol 82 (5) ◽  
pp. 1156-1162 ◽  
Author(s):  
Mark Laikhtman ◽  
Jeffrey S Rohrer
Keyword(s):  
Infant Formula ◽  
Ion Chromatography ◽  
Alkaline Earth ◽  
Collaborative Study ◽  
Powdered Infant Formula ◽  
Enzymatic Method ◽  
Cation Exchange Column ◽  
Suppressed Conductivity Detection ◽  
Good Agreement

Abstract Choline was determined in infant formula by ion chromatography with suppressed conductivity detection. Samples were digested with 1M hydrochloric acid, filtered, diluted, and injected into the chromatographic system. Choline and the alkali and alkaline earth metals were separated on a high-resolution cation-exchange column and detected by suppressed conductivity. The method was linear between 2 and 200 mg/L (r2 = 0.9999), the concentration range of the diluted samples. This method accurately determined choline in powdered, concentrated, and ready-to-feed infant formulas. Recoveries of choline spikes into powdered infant formula at approximately 1, 0.8, 0.5, and 0.2 times the labeled value ranged from 85 to 114%. This method had good agreement for 8 blind duplicates. The values determined for these samples, which were used in an AOAC collaborative study of an enzymatic method, were consistent with the values determined by the enzymatic method.

Determination of Loss on Drying in Roasted Ground Coffee

1968 ◽  
Vol 51 (3) ◽  
pp. 577-579
Author(s):  
Eleanor A McCarron
Keyword(s):  
Reasonable Agreement ◽  
Collaborative Study ◽  
Moisture Loss ◽  
Oven Method ◽  
Vacuum Oven ◽  
Before And After ◽  
Ground Coffee ◽  
Good Agreement

Abstract Moisture loss on drying was determined on five "regular grind" coffees by the air oven method at 105°C and vacuum oven method at 98—100° C before and after grinding. Results for unground and ground samples by the vacuum oven method were in good agreement; results between the two oven methods for unground or ground samples were generally less satisfactory. Collaborative study was conducted by the vacuum oven method only on four unground (as is) samples. Results were in reasonable agreement, and the method is recommended for adoption as official, first action.

Collaborative Study of the Ultraviolet Spectrophotometric Determination of Sulfoxide in Formulations

1968 ◽  
Vol 51 (3) ◽  
pp. 562-564
Author(s):  
Joseph B Haus ◽  
Lazar Manolev
Keyword(s):  
Spectrophotometric Determination ◽  
Silicic Acid ◽  
Spectrophotometric Method ◽  
Collaborative Study ◽  
Poor Correlation ◽  
Complex Nature ◽  
Uv Spectrophotometry ◽  
Standard Samples ◽  
Good Agreement

Abstract A spectrophotometric method for the analysis of sulfoxide formulation was studied by six collaborators. The method consists of separating the sulfoxide from other components by column chromatography on silicic acid with three successive eluting solutions: chloroform, 2% acetone in chloroform, and 1 0% acetone in chloroform. Sulfoxide is removed in the last eluate and is determined by UV spectrophotometry. Solvents, emulsifiers, pyrethrins, compounds related to sulfoxide, and other insecticides are separated by the column. Results on standard samples of four formulations showed good agreement between samples and laboratories with the exception of one sample which, because of its complex nature and low sulfoxide content, resulted in poor correlation within and between the laboratories. It is recommended that the method for the assay of sulfoxide formulations be adopted as official, first action.

Determination of Sulfite in Foods and Beverages by Ion Exclusion Chromatography with Electrochemical Detection: Collaborative Study

1990 ◽  
Vol 73 (2) ◽  
pp. 216-222 ◽  
Author(s):  
Hie-Joon Kim
Keyword(s):  
Electrochemical Detection ◽  
Collaborative Study ◽  
Lemon Juice ◽  
Ion Exclusion Chromatography ◽  
Ion Exclusion ◽  
Exclusion Chromatography ◽  
Mashed Potatoes ◽  
Liquid Chromatographic ◽  
Good Agreement

Abstract A liquid chromatographic (LC) method for determination of total sulfite in foods and beverages by alkali extraction followed by ion exclusion chromatographic separation and electrochemical detection (IEC-EC) was collaboratively studied by 9 laboratories. Blind duplicate samples of starch, diluted lemon juice, wine cooler, dehydrated seafood, and instant mashed potatoes were analyzed without spiking and with added sulfite at 2 levels. The initial sulfite levels varied from 0 to 384 ppm S02, and the levels added varied from 10 to 400 ppm. The initial sulfite levels determined by the IECEC method and the Monler-Williams method were in good agreement. Recovery of added sulfite by the IEC-EC method was generally higher than that by the Monler-Williams method. Within-laboratory repeatability (RSDr) for the IEC-EC method varied from 4.4 to 26.0%, and overall reproducibility (RSDR) varied from 8.5 to 39.3 %. The collaborators found the method to be fast, sensitive, and easy to use, which makes it a useful alternative to the Monler-Williams method. The method has been adopted official first action.

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