Collaborative Study of Colorimetric Methods for Phosphorus in Feeds

1964 ◽  
Vol 47 (3) ◽  
pp. 509-511
Author(s):  
Mary Heckman
Keyword(s):  
Statistical Analysis ◽  
Excellent Agreement ◽  
Phosphorus Content ◽  
Collaborative Study ◽  
Volumetric Method ◽  
Molybdenum Blue ◽  
Calcium Phosphorus ◽  
Feed Samples ◽  
Colorimetric Methods

Abstract Six feed samples of varying phosphorus content and with calcium/phosphorus ratios of 0.5— 2.0 were distributed. Eleven laboratories compared the official volumetric method (22.061) with the molybdenum blue method studied in 1962. Twelve laboratories compared 22.061 with Parks and Dunn's colorimetric molybdovanadate method now used for fertilizers. Means for all methods show excellent agreement. Statistical analysis by Youden's formula shows marked superiority of the molybdovanadate method over the molybdenum blue method.

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.

scholarly journals Determination of Total Phosphorus in Foods by Colorimetry: Summary of NMKL Collaborative Study

1996 ◽  
Vol 79 (6) ◽  
pp. 1408-1410 ◽  
Author(s):  
T Katrhna Pulliainen ◽  
Harriet C Wallin
Keyword(s):  
Total Phosphorus ◽  
Phosphorus Content ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Milk Powder ◽  
Molybdenum Blue ◽  
Relative Standard ◽  
Standard Deviations ◽  
Skimmed Milk Powder

Abstract A collaborative study was conducted to validate a spectrophotometric–colorimetric method for determining total phosphorus in foods. The sample was dry-ashed in the presence of zinc oxide, and total phosphorus content was measured colorimetrically as molybdenum blue. Twelve laboratories from the Nordic countries participated in the study. The test materials included potato flour, sausage, cold ham, infant formula powder, cheese, and skimmed milk powder. Participants received 12 randomly coded samples of 2 blind duplicates of each material. Phosphorus contents of materials varied between 0.076 and 0.96 g/100 g. Relative standard deviations for repeatability of the method varied from 1.1% for 0.96 g phosphorus/100 g to 5.4% for 0.29 g phosphorus/100 g. Relative standard deviations for reproducibility varied from 3.6% for 0.96 g phosphorus/100 g to 7.7% for 0.23 g phosphorus/100 g. The colorimetric method for determination of total phosphorus in foods has been adopted first action by AOAC INTERNATIONAL as an NMKUAOAC INTERNATIONAL method.

Collaborative Study of the Photometric Molyb do vanadate Method for Phosphorus

1965 ◽  
Vol 48 (3) ◽  
pp. 654-657
Author(s):  
Mary Heckman
Keyword(s):  
Collaborative Study ◽  
Gravimetric Method ◽  
Volumetric Method ◽  
Photometric Method ◽  
Coefficients Of Variation ◽  
Standard Deviations ◽  
Official Status ◽  
Feed Samples ◽  
Phosphorus Levels ◽  
Good Agreement

Abstract Sixteen laboratories analyzed five feed samples, with phosphorus levels ranging from about 0.60 to 5.50% by the photometric molybdovanadate method studied in 1963 (This Journal, 46, 836 (1963)), and by either the volumetric method, 22.061, or the gravimetric quinoline molybdate method (ibid., 47, 170 (1964)), both of which have some official status. Eight sets of results based on the volumetric method and eight based on the gravimetric method were available. Means for all methods were in good agreement. Standard deviations and coefficients of variation were satisfactory for all methods, indicating superiority of both volumetric and gravimetric methods over the photometric method. Calculation of standard deviations for the entire range tested, however, showed the photometric method to be superior to the volumetric method and inferior to the gravimetric. The molybdovanadate method was adopted as official, first action.

Determination of Crude Protein in Animal Feeds, Using Block Digestion Followed by Steam Distillation: Collaborative Study

1979 ◽  
Vol 62 (2) ◽  
pp. 290-291
Author(s):  
Rodney J Noel
Keyword(s):  
Statistical Analysis ◽  
Crude Protein ◽  
Steam Distillation ◽  
Collaborative Study ◽  
Alternative Technique ◽  
Animal Feeds ◽  
Ammonia Determination ◽  
Kjeldahl Method ◽  
Feed Samples

Abstract A method consisting of digesting animal feeds in a block digestor and determining ammonia by steam distillation followed by titration has been evaluated and compared with the official final action Kjeldahl method, 7.016. Fifteen laboratories analyzed 5 feed samples and lysine monohydrochloride. Statistical analysis showed that results from the 2 methods were comparable. The distillation technique has been adopted as official first action as an alternative technique for ammonia determination from the digest of the official final action block digestor method, 7.B11.

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.

scholarly journals International Collaborative Study: Structuring and Sample Preparation

Radiocarbon ◽  
1990 ◽  
Vol 32 (3) ◽  
pp. 267-270 ◽  
Author(s):  
G T Cook ◽  
D D Harkness ◽  
B F Miller ◽  
E M Scott ◽  
M S Baxter ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Sample Preparation ◽  
Collaborative Study ◽  
Intercomparison Exercise ◽  
Hierarchical Nature ◽  
Precision And Accuracy ◽  
International Collaborative ◽  
Stage 1 ◽  
Selection Of ◽  
International Collaborative Study

The success of any intercomparison exercise depends largely on participation and cooperation of a sufficient number of laboratories and the selection of a suitable suite of samples. Unless the latter is satisfactorily devised, the former cannot be guaranteed. The hierarchical nature of this study has necessarily resulted in a far more comprehensive set of sample types than has previously been employed. The exercise was structured to satisfy the following criteria: 1) to enable the participating laboratories to assess the experimental precision and accuracy of the component stages of the dating process; 2) samples should be typical of those routinely dated by the laboratories. This takes on a particular significance in Stage 1 where they should resemble as closely as possible the counting medium; 3) an objective statistical analysis of the results at each component stage of the study.

Determining the Yeast Count in Maple Sirup and a Collaborative Study of the Methods and Sampling Techniques

1967 ◽  
Vol 50 (4) ◽  
pp. 747-751
Author(s):  
John C Kissinger
Keyword(s):  
Adverse Effect ◽  
Statistical Analysis ◽  
Collaborative Study ◽  
Cell Suspensions ◽  
Sampling Techniques ◽  
Homogeneous Cell

Abstract Techniques for sampling and a method for determining the yeast count in maple sirup have been studied collaboratively in 22 laboratories. Statistical analysis of collaborators' results indicated that variation in shipping conditions had an adverse effect on the sirup samples and that difficulties in preparing homogeneous cell suspensions in the sirup prior to subsampling caused wide variation in counts. Studies will continue

Results of a Multicenter Study Assessing the Status of Standardization of a Recombinant Thromboplastin for the Control of Oral Anticoagulant Therapy

1994 ◽  
Vol 72 (02) ◽  
pp. 261-267 ◽  
Author(s):  
A Tripodi ◽  
V Chantarangkul ◽  
M Braga ◽  
L poller ◽  
J W ten Cate ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Oral Anticoagulant Therapy ◽  
Oral Anticoagulants ◽  
Collaborative Study ◽  
The Third ◽  
Normal Individuals ◽  
The Status ◽  
Data Points ◽  
Relationship Of ◽  
International Collaborative Study

SummaryAn international collaborative study involving 20 laboratories was undertaken to evaluate the status of standardization of a commerical recombinant thromboplastin. The results show that the reagent fulfills the WHO requirements for thromboplastin calibration against two International Reference Preparations (IRP) from different species, because there was a linear relationship of log-transformed prothrombin times as measured by the recombinant reagent and the two IRPs in normal individuals and patients stabilized on oral anticoagulants. The regression lines drawn through the patient data points passed through the normal data points in the majority of instances. The average ISI values for three different batches were close to unity. On the average, the ISI value calculated against BCT/253 (human, plain) was slightly smaller than that against RBT/79 (rabbit, plain). The between laboratory precision of calibration (CV = 5-6%) did not change whether BCT/253 or RBT/79 was used, whereas it was substantially improved when the calibrations of batches 2 and 3 were performed against batch 1, arbitrarily taken as standard (CV ≤ 1.7%). Statistical analysis to test for differences between slopes revealed no significant between-batch differences in 16 of 20 laboratories. However slight differences for the third batch (2.8% less than the average ISI value of batches 1 and 2) leave room for further improvement in the standardization of the reagent.

Proposed Method for Isolating Coagulase-Positive Staphylococci from Food Products: Report of a Collaborative Study

1966 ◽  
Vol 49 (2) ◽  
pp. 270-273
Author(s):  
Edward F Baer
Keyword(s):  
Statistical Analysis ◽  
Collaborative Study ◽  
Food Products ◽  
Coagulase Positive Staphylococci

Abstract Eleven collaborators studied the reproducibility of the method, proposed in 1965, for the isolation of coagulase-positive staphylococci. Samples studied were milk, beef and turkey samples, and fresh, headless shrimp. Based upon statistical analysis of collaborative results, the laboratory means did not vary significantly. The method is recommended for adoption 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.

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