Collaborative Study of the Determination of Sorbic Acid in Wine

1975 ◽  
Vol 58 (1) ◽  
pp. 133-135
Author(s):  
Arthur Caputi ◽  
Karen Slinkard
Keyword(s):  
Sorbic Acid ◽  
Collaborative Study ◽  
Thiobarbituric Acid ◽  
The Other ◽  
Ultraviolet Spectrophotometry ◽  
Acid Complex ◽  
Average Recovery ◽  
Colorimetric Measurement ◽  
Coefficients Of Variation

Abstract Eleven collaborators participated in a study of 2 methods for determining sorbic acid in wine. One method utilizes ultraviolet spectrophotometry and the other depends on the colorimetric measurement of a thiobarbituric acid complex. Three different wine types were each spiked with 200, 300, and 400 mg sorbic acid/ L. Average recovery ranged from 97.3 to 107.5% with the thiobarbituric acid method with coefficients of variation from 4.4 to 8.7%. The ultraviolet method gave recoveries from 97 to 103.5% with coefficients of variation ranging from 2.0 to 6.4%. Comments on both methods from collaborators were favorable. Both methods have been adopted as official first action.

Collaborative Study of the Determination of Dichlorophene in Veterinary Preparations by Ultraviolet Spectrophotometry

1972 ◽  
Vol 55 (1) ◽  
pp. 163-165
Author(s):  
Dalia M Gilvydis
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Liquid Extraction ◽  
Synthetic Mixture ◽  
Ultraviolet Spectrophotometry ◽  
Average Recovery ◽  
Liquid Liquid Extraction ◽  
Coefficients Of Variation ◽  
Standard Deviations

Abstract Dichlorophene is determined in veterinary preparations by a liquid-liquid extraction and UV quantitation. Eight collaborators each analyzed 4 commercial preparations and one synthetic mixture. The average recovery for dichlorophene in the synthetic mixture is 100.3% with a standard deviation of 2.13. The standard deviations obtained for the 5 samples range from 0.13 to 3.69 with coefficients of variation from 0.69 to 3.43. It is recommended that the method be adopted as official first action.

Gas Chromatographic Methods for Determination of γ-BHC in Technical Emulsifiable Concentrates and Water-Dispersible Powder Formulations and in Lindane Shampoo and Lotion: Collaborative Study

1984 ◽  
Vol 67 (4) ◽  
pp. 834-837
Author(s):  
James W Miles ◽  
Dwight L Mount ◽  
◽  
T J Beckmann ◽  
S K Carrigan ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Internal Standard ◽  
The Other ◽  
Water Dispersible ◽  
Coefficients Of Variation ◽  
Aoac Method ◽  
Liquid Chromatographic ◽  
Gas Chromatographic Separation

Abstract Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.

Spectrofluorometric Determination of Lasalocid Sodium in Finished Feeds and Premixes

1974 ◽  
Vol 57 (3) ◽  
pp. 636-641
Author(s):  
Modest Osadca ◽  
Mercedes Araujo
Keyword(s):  
Standard Deviation ◽  
Ethyl Acetate ◽  
Boric Acid ◽  
Chemical Method ◽  
Sodium Concentration ◽  
Acid Complex ◽  
Average Recovery ◽  
Spectrofluorometric Determination ◽  
Coefficients Of Variation

Abstract A simple, rapid, and sensitive chemical method is described for determining lasalocid sodium in finished poultry feeds and premixes. The drug is extracted with ethyl acetate directly from premixes and after a brief treatment with pH 4.7 buffer from finished feeds. Lasalocid sodium concentration is measured spectrofluorometrically and a correction for nonspecific fluorescence is determined after formation of a lasalocid- boric acid complex. Replicate assays of typical poultry mashes and pellets containing about 0.0075% lasalocid sodium yielded coefficients of variation of 2.8 to 5.0%. Average recovery of lasalocid sodium added in the laboratory at 0.0037, 0.0075, and 0.0112% was 90% with a pooled standard deviation of ±1.86%.

Ruggedness of Official Colorimetric Method for Sorbic Acid in Wine

1977 ◽  
Vol 60 (5) ◽  
pp. 1044-1047
Author(s):  
Arthur Caputi ◽  
Paul A Stafford
Keyword(s):  
Sorbic Acid ◽  
Colorimetric Method ◽  
Slight Modification ◽  
Thiobarbituric Acid ◽  
Important Variable ◽  
Ultraviolet Absorption ◽  
Absorption Method ◽  
Acid Complex ◽  
Colorimetric Measurement ◽  
Color Complex

Abstract Two methods for determining sorbic acid in wine were studied collaboratively in 1974 and both methods were adopted as official first action. The ultraviolet absorption method gave excellent results, but the method using colorimetric measurement of a thiobarbituric acid complex yielded some erratic results. To isolate the source of this problem, the effects of various parameters in the analysis were investigated further. The method of cooling the sample after heating to develop the color complex was the most important variable found, and a slight modification in the wording of the method is proposed. With this change in the thiobarbituric acid procedure, both methods were adopted as official final action.

Determination of Procaine and Related Local Anesthetics. II. Collaborative Study

1975 ◽  
Vol 58 (1) ◽  
pp. 93-94
Author(s):  
Joseph B Proctor ◽  
Thomas D Doyle
Keyword(s):  
Spectrophotometric Determination ◽  
Local Anesthetics ◽  
Active Component ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Ion Pairing ◽  
The Other ◽  
Three Solutions ◽  
Average Recovery

Abstract The ion-pairing chromatographic method reported previously for the isolation and spectrophotometric determination of the local anesthetics, alone and in combination, was studied collaboratively. Three solutions were assayed. One containing procaine as the single active component gave an average recovery of 99.8± 1.7%. A mixture of procaine and tetracaine gave results of 99.3±1.6 and 98.9±8.82%, respectively. A third solution containing procaine and propoxycaine assayed 100.0±1.5 and 99.1±1.9%, respectively. It was shown that low results for tetracaine were due to loss during the final evaporative step. The method for samples containing tetracaine should be studied further. The other methods have been adopted as official first action.

Gas-Liquid Chromatographic Determination of Benzoic Acid and Sorbic Acid in Foods: NMKL1 Collaborative Study

1983 ◽  
Vol 66 (3) ◽  
pp. 775-780
Author(s):  
Bonny K Larsson ◽  
◽  
M Askeland ◽  
M Bergstrøm-Nilsen ◽  
H K Dahle ◽  
...  
Keyword(s):  
Benzoic Acid ◽  
Apple Juice ◽  
Methylene Chloride ◽  
Sorbic Acid ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Caproic Acid ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatographic method for the simultaneous determination of benzoic acid and sorbic acid in foods was collaboratively studied by 8 laboratories. Benzoic and sorbic acids are isolated from food by successive extractions with ether, sodium hydroxide, and methylene chloride, converted to trimethylsilyl (TMS) esters, and determined by gasliquid chromatography. Phenylacetic acid and caproic acid are used as internal standards for benzoic acid and sorbic acid, respectively. Seven samples were collaboratively studied: almond paste, fish homogenate, and apple juice with benzoic and sorbic acid levels from 0.04 to 2 g/kg. Average recoveries {%) for benzoic and sorbic acids were as follows: almond paste, 99.6 and 101.2; fish homogenate, 99.2 and 97.4; and apple juice 98.2 and 106.6. The reproducibility coefficients of variation (%) for benzoic and sorbic acids at 0.5-2 g/kg levels were 3.5-6.1 and 5.2-9.0; and at the 0.04 g/kg level, 14.7 and 23.3, respectively. The method has been adopted official first action at 0.5-2 g/kg levels.

Collaborative Study on the Determination of Aflatoxins in Cottonseed Products

1969 ◽  
Vol 52 (1) ◽  
pp. 61-72
Author(s):  
Walter A Pons
Keyword(s):  
Collaborative Study ◽  
Systematic Errors ◽  
Average Recovery ◽  
Coefficients Of Variation ◽  
Tlc Plates ◽  
High Degree

Abstract Twelve laboratories collaboratively studied a method for estimating aflatoxins in cottonseed products, using both visual and fluorodensilometric estimation of aflatoxins on TLC plates. Average recovery of total aflatoxins (B1 + B2) added to five products was 85% by visual and 90% by densitometric estimation; average coefficients of variation were 18 and 12%, respectively. Within- and between-laboratory precision was essentially equivalent for both types of measurement, with no significant systematic errors among the laboratories. There was a high degree of correlation between visual and densitometric estimation of aflatoxins.

Collaborative Study of the Colorimetric Determination of Sorbic Acid in Cheese

1971 ◽  
Vol 54 (3) ◽  
pp. 663-665
Author(s):  
George Wilamowski
Keyword(s):  
Steam Distillation ◽  
Sorbic Acid ◽  
Potassium Dichromate ◽  
Collaborative Study ◽  
Thiobarbituric Acid ◽  
Colorimetric Determination ◽  
Red Color ◽  
Red Dye ◽  
532 Nm

Abstract After isolation of sorbic acid from cheese by steam distillation, the acid recovered is cleaved with potassium dichromate in acidic medium to form an intermediate malonaldehyde, which, in turn, reacts with 2-thiobarbituric acid to produce a red dye. The absorbance of the red color, measured at 532 nm, is proportional to the concentration of sorbic acid in the sample. Seven collaborators reported recoveries of 96.7–102.4% from cheese samples spiked with 0.05% sorbic acid. This method has been adopted as official first action.

Collaborative Study of the Determination of Dithiocarbamate Residues by a Modified Carbon Disulfide Evolution Method

1971 ◽  
Vol 54 (3) ◽  
pp. 528-532 ◽  
Author(s):  
George E Keppel
Keyword(s):  
Hydrogen Sulfide ◽  
Stannous Chloride ◽  
Collaborative Study ◽  
The Other ◽  
Dilute Acid ◽  
Trap Hydrogen ◽  
Modified Method ◽  
Coefficients Of Variation ◽  
Naoh Solution

Abstract A modified method for determination of dithiocarbamate residue recoveries from grain was studied collaboratively. In this method dilute acid with stannous chloride is added to the crop, which is then heated to boiling for the dithiocarbamate decomposition step. A mixture of NaOH solution and benzene is used to trap hydrogen sulfide and other volatile interferences. Collaborative results were low and erratic, with large coefficients of variation. The results of the Associate Referee, on the other hand, were better. Further study on this method is recommended.

Determination of Several Chlorinated Pesticides by the AOAC Multiresidue Method with Additional Quantitation of Perthane after Dehydrochlorination: Collaborative Study

1973 ◽  
Vol 56 (3) ◽  
pp. 721-727
Author(s):  
Richard T Krause
Keyword(s):  
Parent Compound ◽  
Collaborative Study ◽  
Heptachlor Epoxide ◽  
Chlorinated Pesticides ◽  
Average Recovery ◽  
Multiresidue Method ◽  
Coefficients Of Variation ◽  
Before And After ◽  
Coefficients Of Variations

Abstract The AOAC multiresidue method for chlorinated pesticides, 29.001–29.017, was studied collaboratively by 7 laboratories. Perthane, heptachlor epoxide, mirex, and dieldrin were determined in apple and cauliflower samples fortified at 2 levels, and Perthane was determined in butterfat samples fortified at 2 levels. Perthane was quantitatively measured before and after a simplified dehydrochlorination procedure. Average recoveries and coefficients of variations for pesticides in the apple samples for both levels were: Perthane 100±10%, heptachlor epoxide 102±14%, mirex 96±9%, dieldrin 101±14%, and Perthane (after dehydrochlorination and recalculation to the parent compound) 100±9%. Average recoveries and coefficients of variation for pesticides in the cauliflower samples for both levels were: Perthane 105±9%, heptachlor epoxide 103± 15%, mirex 103±7%, dieldrin 98±11%, and Perthane (after dehydrochlorination and recalculation) 100±10%. The average recovery for both levels of Perthane (after dehydrochlorination and recalculation) in the butterfat samples was 91±10%. For a spinach sample with field-incurred residues the collaborators found an average of 4.47 ppm Perthane before dehydrochlorination and 5.09 ppm Perthane as the olefin after dehydrochlorination. In most instances, the identities of all the residues were confirmed by TLC. The dehydrochlorination technique has been adopted as official first action.

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