Modified Method for Carbadox in Feeds: Collaborative Study

1979 ◽  
Vol 62 (5) ◽  
pp. 982-984
Author(s):  
John T Goras
Keyword(s):  
Standard Deviation ◽  
Room Temperature ◽  
Collaborative Study ◽  
Variance Ratio ◽  
Modified Method ◽  
Repeatability Standard Deviation ◽  
Standard Solution ◽  
The Mean ◽  
Optimum Working ◽  
Statistical Results

Abstract The official first action method for carbadox in swine feed, 42.C01-42.C04, was modified in 2 respects. First, the samples were leached overnight at room temperature instead of boiled for 1 hr. This change avoided problems with overheating and excessive evaporation. Second, the dilution scheme for samples spiked with carbadox standard solution was changed to give absorbance values that were within the optimum working range of all types of spectrophotometers. The modified procedure was collaboratively studied by 21 laboratories. The repeatability standard deviation (σo) and reproducibility standard deviation (σo) were σ0 = 0.00029% and σx = 0.00056% (8.9% of grand mean) for feeds containing 0.00617% carbadox; and σo = 0.0012% and σx = 0.0019% (9.3% of grand mean) for feeds containing 0.0198% carbadox. The between-laboratory variance ratio was significant for feeds containing 0.0198% carbadox. The mean per cent of intent values for feeds containing 0.00617% carbadox and 0.0198% carbadox were 102% and 104%, respectively. In general, the statistical results were comparable to those previously obtained for the official first action method. Consequently, the modified procedure is not recommended as a replacement for the official first action method.

Colorimetric Method for Carbadox in Feeds: Collaborative Study

1977 ◽  
Vol 60 (5) ◽  
pp. 1059-1063
Author(s):  
John T Goras
Keyword(s):  
Standard Deviation ◽  
Stannous Chloride ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Feed Supplement ◽  
Colored Complex ◽  
Feed Supplements ◽  
Repeatability Standard Deviation ◽  
Standard Additions ◽  
The Mean

Abstract A colorimetric method for determining carbadox in complete swine feeds and feed supplements was collaboratively studied. Carbadox is separated from feed with CHCl3-methanol (3+1) and then separated from interfering materials by a series of solvent-solvent extractions. The drug is isolated as a dry residue, reconstituted, and reacted with stannous chloride to form a colored complex that is measured at 520 nm. The method of standard additions is used to compensate for a feed or feed supplement matrix effect. Twenty-seven laboratories assayed feeds containing 0.0013, 0.0053, and 0.0242% carbadox. The repeatability standard deviation (σ0) and reproducibility standard deviation (σx) were σ0 = 0.00014%, σx = 0.00035% (29% of grand mean) for 0.0013% carbadox in feed; σ0 = 0.00025%, σx = 0.00037% (6.7% of grand mean) for 0.0053% carbadox in feed; and σ0 = 0.0019%, σx = 0.0024% (9.6% of grand mean) for 0.0242% carbadox in feed. The between-laboratory variance ratio was not significant for feeds containing 0.0013 and 0.0053% carbadox, but was significant for feeds containing 0.0242% carbadox. The mean recovery values for feeds containing 0.0013, 0.0053, and 0.0242% carbadox were 92, 104, and 103%, respectively. The method was adopted as official first action for feeds having a guaranteed potency of 0.0055% carbadox or higher.

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.

scholarly journals Fine Tuning a Bile-Enzymatic-Gravimetric Total Dietary Fiber Method

1997 ◽  
Vol 80 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Kenneth J Cranker ◽  
Katherine M Phillips ◽  
Maria Carmen Rita V Gonzales ◽  
Kent K Stewart
Keyword(s):  
Standard Deviation ◽  
Dietary Fiber ◽  
Collaborative Study ◽  
Original Method ◽  
Fine Tuning ◽  
Official Method ◽  
Total Dietary Fiber ◽  
Modified Method ◽  
Relative Standard ◽  
Wet Weight

Abstract A recently proposed bile-enzymatic-gravimetric total dietary fiber (TDF) method was modified and the new procedure was compared with the original method, the traditional AOAC enzymatic-gravimetric determination (AOAC Official Method 985.29), and another simplified AOAC procedure by analyzing several diet composites, including National Institute of Standards and Technology 1548 total diet reference material. The original and modified bile-enzymatic-gravimetric procedures also were compared by analyzing 9 food samples from a collaborative study of the original method. The modified method consistently yielded values about 10% lower than the original method but closer to reference values and to values from AOAC Offical Method 985.29, suggesting results that are more in line with accepted TDF standard methodology. Our modified method was used to analyze 180 fresh-frozen diet composites with TDF values ranging from 0.6 to 3.2 g/100 g wet weight. Samples were from 2 multicenter feeding studies sponsored by the National Heart, Lung and Blood Institute: DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activity) and DASH (Dietary Approaches to Stop Hypertension). The mean relative standard deviation (RSD) for duplicate analyses was 1.1%. For 40 assays of a quality control diet composite over 9 months, the standard deviation was 0.1 g/100 g wet weight (4.9% RSD), indicating the method’s excellent precision for routine use.

Collaborative Study of an Automated Optical Somatic Cell Counting Method for Raw Milk

1973 ◽  
Vol 56 (4) ◽  
pp. 950-956
Author(s):  
Wesley N Kelley
Keyword(s):  
Standard Deviation ◽  
Somatic Cell ◽  
Collaborative Study ◽  
Sampling Rate ◽  
Raw Milk ◽  
Cell Counting ◽  
Counting Method ◽  
Milk Samples ◽  
Comparison Of Results ◽  
Statistical Results

Abstract A collaborative study was conducted to compare tbe automated optical somatic cell counting method (OSCC) with the direct microscopic somatic cell counting method (DMSCC) for raw milk. Samples were prefixed with formaldehyde and introduced into an Auto-Analyzer system. Dilution, clarification, and cell counting were performed automatically. Eight collaborators participated in the study, analyzing 48 samples in duplicate, using 2 different sampling rates. The results were compared with DMSCC counts reported by 3 different analysts. Statistical results show that the standard deviation for the DMSCC method was 0.1086 and for the OSCC method, at a sampling rate of 30/hr, 0.0911. From comparison of results it appears that the OSCC method is as accurate as, and more precise than, the DMSCC method. The faster sampling rate of the OSCC method (60/hr) has some effect on precision but little effect on accuracy. The method has been adopted as official first action.

Experimental Designs for Interlaboratory Precision Experiments: Comparison of ISO 5725 with Draft NEN 6303

1989 ◽  
Vol 72 (1) ◽  
pp. 34-37 ◽  
Author(s):  
J Zaalberg
Keyword(s):  
Standard Deviation ◽  
Edible Oils ◽  
Collaborative Study ◽  
Experimental Designs ◽  
Interlaboratory Experiments ◽  
Interlaboratory Studies ◽  
Repeatability Standard Deviation ◽  
Level Design ◽  
Iso 5725

Abstract To determine the precision of standardized analytical methods, interlaboratory experiments are carried out in which several laboratories analyze identical samples from well homogenized batches of material. From the test results, estimates of the standard deviations under repeatability as well as under reproducibility conditions are calculated. In the present work, the experimental designs recommended in the International Standard ISO 5725 have been compared with a design proposed in the draft Netherlands Standard NEN 6303. This has been done by comparing their mathematical models as well as by applying them to the results of a recent collaborative study on the determination of heavy metals in edible oils and fats. The reproducibility standard deviation is estimated equally well with both Standards, but it appeared that the designs given in ISO 5725 can lead to serious underestimation (uniform-level design) or overestimation (split-level design) of the repeatability standard deviation. By using the design proposed in NEN 6303, these biases can be avoided. Hence, it is recommended that interlaboratory studies be organized according to the design of NEN 6303.

δ18 Measurements in Water for Detection of Sugar Beet-Derived Syrups in Frozen Concentrated Orange Juice: Collaborative Study

1992 ◽  
Vol 75 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
Landis W Doner, ◽  
Allan R Brause ◽  
Donald R Petrus
Keyword(s):  
Mass Spectrometry ◽  
Standard Deviation ◽  
Stable Isotope ◽  
Sugar Beet ◽  
Orange Juice ◽  
Isotope Ratio ◽  
Collaborative Study ◽  
Isotope Ratio Mass Spectrometry ◽  
Stable Isotope Ratio ◽  
The Mean

Abstract Stable isotope ratio mass spectrometry has shown that pure frozen concentrated orange juices (FCOJ) of 63-67° brix possess a mean δ18 value of +14.28%o, with a standard deviation of 1.80. Beet invert syrups, which are produced using ground water, possess negative values. As a result, δ18 values decrease on addition of such syrups to FCOJ. Samples with values less than +8.9%o (3 standard deviations from the mean for pure FCOJs) can confidently be considered as adulterated. A collaborative study was conducted in which a pure FCOJ and 4 samples adulterated to various levels with medium beet invert syrup were sent to each of 6 collaborators. In all but 2 instances, juices containing more than 10% beet syrup would have been classified as adulterated by the collaborators; none would have classified pure juice as adulterated. The plot of mean δ18 values for all collaborators at each adulteration level has a correlation coefficient >0.999. The method has been adopted first action by AOAC International.

Accuracy of Peanut Moisture Determinations by Using the Official AOCS Method1

1975 ◽  
Vol 2 (1) ◽  
pp. 29-32
Author(s):  
G. H. Brusewitz ◽  
T. B. Whitaker ◽  
J. H. Young
Keyword(s):  
North Carolina ◽  
Standard Deviation ◽  
Collaborative Study ◽  
Moisture Determination ◽  
State University ◽  
Aocs Method ◽  
Oklahoma State University ◽  
North Carolina State University ◽  
The Mean ◽  
Official Aocs

Abstract A collaborative study was conducted using Spanish peanuts at Oklahoma State University and Virginia peanuts at North Carolina State University regarding the variability in moisture determination using the official AOCS method. The variability among 30 samples was estimated at 5 moisture levels for each of the two peanut types. No difference could be detected between the two types and the data were combined. The standard deviation was linearly related to the mean moisture. Data provided information necessary to compute the number of samples required for a desired precision.

Evaluation of the Babcock Method for the Determination of Milk Fat

1975 ◽  
Vol 58 (5) ◽  
pp. 949-956
Author(s):  
Myron R Mckinley ◽  
Richard E Arnold ◽  
John B Rosenbury ◽  
Earl C Born ◽  
Chapman E Dunham ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Standard Deviation ◽  
Milk Fat ◽  
Collaborative Study ◽  
Tempering Temperature ◽  
Coefficients Of Variation ◽  
Sample Composition ◽  
Significant Difference ◽  
Repeatability Standard Deviation ◽  
Milk Solids

Abstract The Babcock test for fat in milk was evaluated to study the effects of variables such as glassware calibration, sample preparation, sample composition, reagents, tempering conditions, procedural variations, and analyst. Certain test bottles yielded significantly different results; however, there was little indication of pipet variation. Analysis of the various techniques for tempering and mixing indicated that samples tempered at 68°F (20°C), containing an airspace of approximately 25% of the total container, and mixed by inversion 5–10 times or poured from one container to another gave the most consistent results. Sample composition did not affect results, provided all milk-solids-notfat were digested by the sulfuric acid. A pipet draining time of 10 sec followed by blowing out the pipet was sufficient to yield reproducible results. Differences between lots of sulfuric acid affected results. Results were 0.027% less when the final test tempering was 130°F (54.5°C) compared to 140°F (60°C); however, a final tempering for a minimum of 3 min gave satisfactory results. Variations in reading results between individual analysts were negligible. The Babcock method for fat in milk, modified to include the optimum parameters as determined in this study, was subjected to a collaborative study. Nine laboratories analyzed 10 samples in duplicate. Statistical analysis of collaborative data indicates a significant difference between laboratories (p <0.01 ). The repeatability standard deviation of the method is 0.0183%. The reproducibility standard deviation is 0.0407%. The repeatability and reproducibility coefficients of variation are 0.53 and 1.17%, respectively. On the basis of the collaborative results, the following changes have been incorporated into the official final action method: specifications for the reading light; sample draining time; tempering temperature of the acid; tempering procedure for reading the test bottle.

Combination of Total Solids Determined by Oven Drying and Fat Determined by Mojonnier Extraction for Measurement of Solids-Not-Fat Content of Raw Milk: Collaborative Study

1989 ◽  
Vol 72 (5) ◽  
pp. 719-724 ◽  
Author(s):  
Jenny L Clark ◽  
David M Barbano ◽  
Chapman E Dunham
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Raw Milk ◽  
Fat Content ◽  
Oven Drying ◽  
Total Solids ◽  
Ether Extraction ◽  
Relative Standard ◽  
The Mean ◽  
Forced Air

Abstract Each of 9 laboratories analyzed 9 pairs of blind duplicate raw milk samples for fat, using the Mojonnier ether extraction method (16.E13-16.E17), and for total solids, using a new direct forced air oven method. Solids-not-fat was determined by subtracting percent fat from percent total solids. The solids-not-fat content of the samples tested in the collaborative study ranged from 8.48 to 9.36%. The average repeatability standard deviation (sr) and the average reproducibility standard deviation (sR) for the solids-not-fat method were 0.019 and 0.041, respectively. Average repeatability (RSDr) and reproducibility (RSDR) relative standard deviations were 0.218 and 0.466%, respectively. The mean repeatability value (r) was 0.055; the mean reproducibility value (R) was 0.117. The difference between milk total solids determined by direct forced air oven drying and milk fat determined by Mojonnier ether extraction has been approved for interim official first action for determination of solids-not-fat content of milk.

Mass Loss on Drying for Instant Coffee: Collaborative Study

1980 ◽  
Vol 63 (2) ◽  
pp. 178-179
Author(s):  
William P Clinton ◽  
Paul H Manni ◽  
John M Ferry
Keyword(s):  
Standard Deviation ◽  
Mass Loss ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Instant Coffee ◽  
Reproducibility Standard Deviation ◽  
Repeatability Standard Deviation ◽  
Working Method

Abstract A collaborative study was undertaken to define an acceptable routine working method for determination of mass loss in instant coffee. Fourteen laboratories of 24 invited to participate submitted results. The repeatability standard deviation and coefficient of variation were 0.026 and 0.7%, respectively. The reproducibility standard deviation and coefficient of variation were 0.153 and 3.8%, respectively. The method has been adopted as official first action.

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