Cryoscopy of Milk: Effect of Variations in the Method

1966 ◽  
Vol 49 (3) ◽  
pp. 511-515 ◽  
Author(s):  
R W Henningson
Keyword(s):  
Statistical Analysis ◽  
Sample Size ◽  
Freezing Point ◽  
Collaborative Study ◽  
Sample Temperature ◽  
Milk Samples ◽  
Two Samples ◽  
Temperature Rate

Abstract Bath level, sample temperature, rate of stirring, degree of supercooling, sample size, sample isolation, and refreezing of the sample were the variables in the thermistor cryoscopic method for the determination of the freezing point value of milk chosen for study. Freezing point values were determined for two samples of milk and two secondary salt standards utilizing eight combinations of the seven variables in two test patterns. The freezing point value of the salt standards ranged from –0.413 to –0.433°C and from –0.431 to –0.642°C. The freezing point values of the milk samples ranged from –0.502 to –0.544°C and from –0.518 to –0.550°C. Statistical analysis of the data showed that sample isolation was a poor procedure and that other variables produced changes in the freezing point value ranging from 0.001 to 0.011°C. It is recommended that specific directions be instituted for the thermistor cryoscopic method, 15.040–15.041, and that the method be subjected to a collaborative study.

Collaborative Study of the Kjeldahl Method for Determination of Protein Content of Milk

1969 ◽  
Vol 52 (1) ◽  
pp. 126-130
Author(s):  
D R Strang ◽  
J W Sherbon
Keyword(s):  
Statistical Analysis ◽  
Standard Deviation ◽  
Protein Content ◽  
Analysis Of Variance ◽  
Collaborative Study ◽  
Protein Analysis ◽  
Average Standard Deviation ◽  
Milk Samples ◽  
Kjeldahl Method

Abstract Nitrogen in 12 milk samples was measured in 19 laboratories by the Kjeldahl method. Three of the 19 laboratories were excluded from statistical analysis because the nitrogen values they reported differed markedly from those reported by the remaining 16 laboratories. The average standard deviation for the determinations was 0.012% nitrogen, which is equal to 0.077% protein. Analysis of variance indicated that the error due to the laboratories effect was significant when 16 laboratories were considered. When the laboratories were sorted according to various experience criteria, the variations due to laboratories were significant. When the laboratories were blocked according to catalyst used, the variation among laboratories was not significant.

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.

Determination of the Freezing Point of Milk by Thermistor Cryoscopy

1967 ◽  
Vol 50 (3) ◽  
pp. 533-537
Author(s):  
R W Henningson
Keyword(s):  
Freezing Point ◽  
Official Method ◽  
Milk Samples ◽  
Present Official Method ◽  
Proper Condition

Abstract Specific directions for the thermistor cryoscopic method, including uniformity in cooling, degree of supercooling, seeding, and reading procedures, are proposed for the present official method. It is emphasized that the instrument must be in the proper condition for use, must be properly calibrated, and must be properly utilized by the analyst. Each analyst should individually calibrate with standards by the same uniform procedure for standards and milk samples. The precautions necessary in the determination are part of the method and must be observed if the same sample is to yield the same freezing point value for different analysts, in different laboratories, at different times

Collaborative Study of the Milko-Tester Method for Measuring Fat in Homogenized and Unhomogenized Milk

1975 ◽  
Vol 58 (3) ◽  
pp. 572-575
Author(s):  
W Frank Shipe ◽  
Gary F Senyk
Keyword(s):  
Collaborative Study ◽  
Calibration Standards ◽  
Milk Samples ◽  
Automated Method ◽  
Standard Deviations

Abstract The Mark III Industrial Model Milko-tester was evaluated to determine its reliability for testing both unhomogenized and homogenized milk samples. Six laboratories participated in 2 trials. In the first trial, the range among laboratories for homogenized milk was 0.29% and unhomogenized milk 0.34%. This variation was apparently due to inaccurate calibrations. In the second trial, 2 calibration standards were used for each type of milk and the range was reduced to 0.04% for homogenized milk and 0.05% for unhomogenized milk. The standard deviations for unhomogenized and homogenized milk were 0.008 and 0.010 for trial 1 and 0.005 and 0.005 for trial 2, respectively. The official first action automated method I for the determination of fat in raw, unhomogenized milk has been expanded to include the determination of fat in homogenized milk by the use of the Mark III Industrial Model Milko-tester.

Determination of Zearalenone in Corn: Collaborative Study

1976 ◽  
Vol 59 (3) ◽  
pp. 666-670
Author(s):  
Odette L Shotwell ◽  
Marion L Goulden ◽  
Glenn A Bennett
Keyword(s):  
Statistical Analysis ◽  
Thin Layer ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Corn Sample ◽  
Yellow Corn ◽  
Coefficients Of Variation ◽  
The Mean

Abstract Corn samples spiked at levels of 100, 300, 1000, and 2000 μg zearalenone/kg were sent to 22 collaborators for analysis by the Eppley method. All samples were yellow corn except one white corn sample spiked at 2000 μg/kg. Results from 16 collaborators were statistically analyzed. Only 4 of 16 collaborators detected zearalenone in the sample containing 100 μg/kg, but 11 detected the toxin in the sample containing 300 μg/kg. Average recoveries from all samples were 129% at 300 μg/kg, 101% at 1000 μg/kg, and 88% at 2000 μg/kg. The between-laboratory coefficients of variation were 53.0% at 300 μg/kg, 38.2% at 1000 μg/kg, and 27.0% at 2000 μg/kg. Five naturally contaminated corn samples, one in triplicate, were also provided. The mean level of zearalenone in the naturally contaminated samples ranged from 431 to 7622 μg/kg. The mean coefficient of variation for all samples was 40.5%. Two collaborators measured quantities of zearalenone on thin layer chromatographic plates densitometrically. Their results were not included in the statistical analysis, but the results indicated that densitometric measurement, given proper dilutions of solutions, could be used. The method has been adopted as 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.

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 Comparison of Colorimetric and Potentiometric Methods for Parathion and Methyl Parathion in Formulations

1964 ◽  
Vol 47 (2) ◽  
pp. 242-244
Author(s):  
Kenneth Helrich
Keyword(s):  
Statistical Analysis ◽  
Methyl Parathion ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Volumetric Method ◽  
Two Samples

Abstract A collaborative study was conducted to compare the official volumetric method for parathion with the first action colorimetric method, as revised. Two samples of 15% powders were tested. Simultaneously one sample of methyl parathion was submitted to each collaborator for analysis by the above methods and by an infrared procedure. Based on statistical analysis of collaborative results, the revised colorimetric method is recommended for adoption as official, final action; further study of methods for methyl parathion is considered necessary.

Liquid Chromatographic Determination of Lactose Purity: Collaborative Study

1984 ◽  
Vol 67 (5) ◽  
pp. 899-901
Author(s):  
Janice R Saucerman ◽  
Charles E Winstead ◽  
◽  
P J Casaletto ◽  
N J DeAngelis ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Study Data ◽  
Reference Standard ◽  
Mobile Phase Flow Rate ◽  
Equal Concentration ◽  
Liquid Chromatographic

Abstract Results from 8 laboratories are presented for the collaborative study of a proposed method for quantitative liquid chromatographic (LC) determination of lactose purity. Each laboratory was provided with 10 blind duplicate, edible-grade lactose samples plus a lactose reference standard and a fructose internal standard. Testing required the comparison of aqueous 2% lactose sample solution against a reference standard of equal concentration and quantitation by using a fructose internal standard. The LC system specified an isocratic acetonitrilewater (80 + 20) mobile phase, flow rate 2.0 mL/min, and chromatographic separation on a carbohydrate column. Compounds were detected by using refractive index. Statistical analysis for all study data indicates excellent between-laboratory precision with a coefficient of variation (CV) range of 0.53-1.37% and an overall average of 0.977%. Statistical analysis after excluding outliers showed equally good repeatability and reproducibility of less than 1 % and 1.5% CV, respectively. The method has been adopted official first action.

scholarly journals Statistical Analysis for Comparison of the Results Obtained by Capillary Columns and Packed Columns in the Determination of Water Yield in Smoke Condensates Analyzed in Cigarettes for the 24th Asia Collaborative Study

2020 ◽  
Vol 29 (2) ◽  
pp. 97-118
Author(s):  
Hisayuki Takahashi ◽  
Masayasu Tanaka
Keyword(s):  
Statistical Analysis ◽  
Capillary Column ◽  
Collaborative Study ◽  
Capillary Columns ◽  
Packed Columns ◽  
Water Yield ◽  
Yield Data ◽  
Repeatability And Reproducibility ◽  
Comparison Of The Results

SummaryRecently, capillary columns have been widely used in the methodology for the determination of water yields in smoke condensate, even though ISO 10362-1:1999, “Cigarettes - Determination of water in smoke condensates – Part 1: Gas chromatographic method” specifies a packed gas chromatographic column. As a result of a systematic review in 2015, ISO/TC126 decided to revise the standard to include the use of capillary columns.The goal of this study was to confirm the comparability of water yields obtained from capillary column methodology to those yields from packed columns by the statistical analysis of yield data from the 24th Asia Collaborative Study which included 86 datasets submitted by 64 laboratories. After the exclusion of outliers by Cochran’s and Grubbs’ tests, the datasets were classified by GC column type and then mean water yields, and their repeatability and reproducibility were calculated for each type of column. No significant differences were observed in water yields between capillary and packed columns. Repeatability and reproducibility of water yields using capillary column were comparable to those using packed columns as described in ISO 10362-1:1999. From these results, it was confirmed that the capillary columns are an appropriate alternative to packed columns for the gas chromatographic procedure described in ISO 10362-1:1999.

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