Colorimetric Determination of Alkaline Phosphatase as Indicator of Mammalian Feces in Corn Meal: Collaborative Study

1986 ◽  
Vol 69 (3) ◽  
pp. 496-498
Author(s):  
Harriet Gerber ◽  
◽  
B Beavin ◽  
S Brown ◽  
J Bryce ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Agar Medium ◽  
Collaborative Study ◽  
Official Method ◽  
Colorimetric Determination ◽  
Corn Meal ◽  
Small Particles ◽  
Red Color ◽  
Repeatability And Reproducibility

Abstract In the official method for rodent filth in corn meal, filth and corn meal are separated in organic solvents, and particles are identified by the presence of hair and a mucous coating. The solvents are toxic, poor separation yields low recoveries, and fecal characteristics are rarely present on all fragments, especially on small particles. The official AOAC alkaline phosphatase test for mammalian feces, 44.181-44.184, has therefore been adapted to determine the presence of mammalian feces in corn meal. The enzyme cleaves phosphate radicals from a test indicator/substrate, phenolphthalein diphosphate. As free phenolphthalein accumulates, a pink-to-red color develops in the gelled test agar medium. In a collaborative study conducted to compare the proposed method with the official method for corn meal, 44.049, the proposed method yielded 45.5% higher recoveries than the official method. Repeatability and reproducibility for the official method were roughly .1.8 times more variable than for the proposed method. The method has been adopted official first action.

Microbiological Determination of Neomycin in Feeds: Collaborative Study

1989 ◽  
Vol 72 (2) ◽  
pp. 237-241
Author(s):  
Gerald L Stahl ◽  
D Dal Kratzer ◽  
Charles W Kasson
Keyword(s):  
Statistical Analysis ◽  
Confidence Interval ◽  
Salt Concentration ◽  
Agar Medium ◽  
Collaborative Study ◽  
Tris Buffer ◽  
Official Method ◽  
The Mean ◽  
Swine Feed

Abstract A modification of the AOAC microbiological determination of neomycin in feeds was collaboratively studied by 12 laboratories. The official method was modified by substituting a constant salt concentration diluent for the feed extract diluent, preparing the agar medium in tris buffer, and performing the test with a monolayer plating system. Each laboratory performed single assays on 8 samples in a randomized sequence. The samples included duplicates of a cattle and swine feed at 2 different marketed concentrations. The mean recovery across all laboratories was 110.7% of theory with a range of means of 69.4-128.6 across the 12 laboratories. The results of one laboratory and 2 additional values from different laboratories were deemed outliers and excluded from statistical analysis. The statistical analysis gave a confidence interval of ± 26% for individual assays.

Chemical Test for Mammalian Feces: Collaborative Study

1981 ◽  
Vol 64 (1) ◽  
pp. 196-198
Author(s):  
Joel J Thrasher ◽  
John S Gecan ◽  
◽  
R Bradicich ◽  
M Chaput ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Chemical Method ◽  
Collaborative Study ◽  
Basic Medium ◽  
Correct Identification ◽  
Colorimetric Determination ◽  
Chemical Test ◽  
Color Development

Abstract A chemical method was developed to determine the presence of mammalian feces in food. The method consisted of the colorimetric determination of alkaline phosphatase and involved the splitting of the phosphate radical from phenolphthalein diphosphate and the resultant color development of phenolphthalein in a basic medium. A collaborative study testing the feces of 22 animals resulted in a 95% correct identification of samples as mammalian feces. The method has been adopted official first action.

Analyses of Fat-Soluble Vitamins, XIV. Collaborative Study of the Determination of Vitamin D in Multivitamin Preparations

1977 ◽  
Vol 60 (1) ◽  
pp. 151-154
Author(s):  
Frits J Mulder ◽  
Ellen J De Vries ◽  
Ben Borsje
Keyword(s):  
Vitamin D ◽  
Polyethylene Glycol ◽  
Vitamin A ◽  
Colorimetric Assay ◽  
Collaborative Study ◽  
Official Method ◽  
Colorimetric Determination ◽  
Trans Isomers ◽  
Decomposition Products

Abstract The colorimetric assay for the determination of vitamin D (4000—50,000 international units (IU)/g) in multivitamin preparations has been collaboratively studied. The method is based on the same principle as the official method for the determination of vitamin D in concentrates, i.e., elimination of trans-isomers of vitamin D resins. The method includes the following steps: saponification and extraction (isolation of unsaponifiable material), phosphate-treated alumina column chromatography (elimination of tocopherols and vitamin A decomposition products), partition chromatography with polyethylene glycol 600 and Celite (separation of vitamin D fraction from vitamin A alcohol), adsorption chromatography on Florex (elimination of vitamin A decomposition products and small amounts of polyethylene glycol 600), maleic anhydride addition reaction (elimination of trans-isomers of vitamin D resins), and colorimetric determination at 2 wavelengths with and without acetic anhydride (an inhibitor for the color reaction of vitamin D and antimony trichloride). The mean result of 4 laboratories for 8 different samples, expressed as per cent of the known amount of vitamin D added, was 95.8% with a coefficient of variation of 10.5%. Considering the complexity of the method, the collaborative results were reasonable. The method has been adopted as official first action.

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.

Colorimetric Determination of Hydroxyproline as Measure of Collagen Content in Meat and Meat Products: NMKL Collaborative Study

1990 ◽  
Vol 73 (1) ◽  
pp. 54-57 ◽  
Author(s):  
Kurt Kolar
Keyword(s):  
Collaborative Study ◽  
Colorimetric Method ◽  
Meat Products ◽  
Acid Oxidation ◽  
Colorimetric Determination ◽  
Mean Values ◽  
Collaborative Studies ◽  
Freeze Dried ◽  
Analytical Result

Abstract A colorimetric method for the determination of hydroxyproline as a measure of collagen in meat and meat products has been collaboratively studied in 18 laboratories. The method includes hydrolysis with sulfuric acid, oxidation with chloramine- T, and formation of a reddish purple complex with 4- dimethylaminobenzaldehyde. Five frozen and 3 freeze-dried samples were tested, ranging in content from 0.11 to 0.88% and from 0.39 to 4.0% hydroxyproline, respectively. The mean values of 2 identical samples were 0.245 and 0.251 %. The average recovery from a spiked sample was 96.1 %. The hydroxyproline content of a known sample (a mixture of 2 samples in the ratio 5:2) was calculated to 1.42%, which agrees well with the analytical result, 1.40%. In comparison with other collaborative studies, based on the ISO analytical method, the repeatability and reproducibility of this method agree well with the other results. This method was accepted as an official NMKL method by all national Committees, and has been adopted official first action by AOAC as an NMKLAOAC method.

Convection Oven Determination of Loss of Mass on Drying of Quick Frozen French Fried Potatoes: Collaborative Study

1984 ◽  
Vol 67 (3) ◽  
pp. 635-636 ◽  
Author(s):  
David O Biltcliffe ◽  
Hillary J Judd ◽  
Roger Wood ◽  
◽  
A C Bushnell ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Frozen Foods ◽  
Codex Alimentarius Commission ◽  
Convection Oven ◽  
Economic Commission ◽  
Two Samples ◽  
Repeatability And Reproducibility ◽  
Loss Of Mass ◽  
Fried Potatoes

Abstract A collaborative study was carried out on one of the methods submitted to the Joint Economic Commission for Europe (ECE)/Codex Alimentarius Commission Group of Experts on the Standardization of Quick Frozen Foods for the determination of moisture in quick frozen french (fried potatoes. The method was based on the determination of loss of mass of the sample on drying in a convection oven 16 h at 103±2°C. Two samples of uncooked quick frozen french fried potatoes and 2 samples of oven quick frozen french fried potatoes were analyzed by 14 and 13 laboratories, respectively. The method is simple and was found to be analytically satisfactory with repeatability and reproducibility values of 0.21 and 2.00 g/100 g french fried potatoes, and 0.29 and 3.00 g/100 g oven french fried potatoes, respectively. The method was adopted by the Group of Experts in preference to other proposed procedures for this determination. The method has been adopted official first action by AOAC.

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 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.

Colorimetric Determination of the Progestational Steroids in Contraceptive Tablets

1970 ◽  
Vol 53 (4) ◽  
pp. 831-833
Author(s):  
John Y P Wu
Keyword(s):  
Oral Contraceptive ◽  
Medroxyprogesterone Acetate ◽  
Collaborative Study ◽  
Chloroform Extract ◽  
Colorimetric Determination ◽  
Standard Deviations ◽  
Isonicotinyl Hydrazide ◽  
Norethindrone Acetate

Abstract Norethindrone, norethindrone acetate, dimethisterone, medroxyprogesterone acetate, and norethynodrel are determined in oral contraceptive tablets. For the first 4 compounds, a chloroform extract of the tablets is treated directly with isonicotinyl hydrazide reagent to produce a stable color which is measured at 380 nm. The chloroform extract of norethynodrel tablets is isomerized before the reagent is added. An intralaboratory study gave good results, with standard deviations of 0.74 to 1.21%. A collaborative study is recommended.

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.

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