Division 8 Results of a collaborative study
United Kingdom
An EC collaborative study (4th intercomparison) was arranged in which three samples were analysed by up to 12 laboratories to certify the method for hydrolysis. Replicate (5) analyses were performed on each sample. The results are given in the following table:
| Sample 1Pig feed | Sample 2Pig feed supplemented with L-tryptophan | Sample 3Feed concentrate for pigs | |
|---|---|---|---|
| L | 12 | 12 | 12 |
| n | 50 | 55 | 50 |
| Mean [g/kg] | 2,42 | 3,4 | 4,22 |
| sr [g/kg] | 0,05 | 0,05 | 0,08 |
| r [g/kg] | 0,14 | 0,14 | 0,22 |
| CVr [%] | 1,9 | 1,6 | 1,9 |
| SR [g/kg] | 0,15 | 0,2 | 0,09 |
| R [g/kg] | 0,42 | 0,56 | 0,25 |
| CVR [%] | 6,3 | 6,0 | 2,2 |
number of laboratories submitting results
number of single results retained eliminating outliers (identified by Cochran, Dixon outlier test)
standard deviation of repeatability
standard deviation of reproducibility
repeatability
reproducibility
coefficient of variation of repeatability, %
coefficient of variation of reproducibility, %
Another EC collaborative study (3rd intercomparison) was arranged in which two samples were analysed by up to 13 laboratories to certify the method for extraction of free tryptophan. Replicate (5) analyses were performed on each sample. The results are given in the following table:
| Sample 4Wheat and soya mixture | Sample 5Wheat and soya mixture (= sample 4) with added tryptophan (0,457g/kg1) | |
|---|---|---|
| L | 12 | 12 |
| n | 55 | 60 |
| Mean [g/kg] | 0,391 | 0,931 |
| sr [g/kg] | 0,005 | 0,012 |
| r [g/kg] | 0,014 | 0,034 |
| CVr [%] | 1,34 | 1,34 |
| SR [g/kg] | 0,018 | 0,048 |
| R [g/kg] | 0,05 | 0,134 |
| CVR [%] | 4,71 | 5,11 |
number of laboratories submitting results
number of single results retained after eliminating outliers (identified by Cochran, Dixon outlier test)
standard deviation of repeatability
standard deviation of reproducibility
repeatability
reproducibility
coefficient of variation of repeatability, %
coefficient of variation of reproducibility, %
Another EC intercomparison study was arranged in which four samples were analysed by up to 7 laboratories with the aim of a tryptophan certification for hydrolysis. The results are given below. Replicate (5) analyses were performed on each sample.
| Sample 1Mixed pig feed(CRM 117) | Sample 2Low fat fish meal(CRM 118) | Sample 3Soybean meal(CRM 119) | Sample 4Skimmed milk powder(CRM 120) | |
|---|---|---|---|---|
| L | 7 | 7 | 7 | 7 |
| n | 25 | 30 | 30 | 30 |
| Mean [g/kg] | 2,064 | 8,801 | 6,882 | 5,236 |
| sr [g/kg] | 0,021 | 0,101 | 0,089 | 0,04 |
| r [g/kg] | 0,059 | 0,283 | 0,249 | 0,112 |
| CVr [%] | 1,04 | 1,15 | 1,3 | 0,76 |
| SR [g/kg] | 0,031 | 0,413 | 0,283 | 0,221 |
| R [g/kg] | 0,087 | 1,156 | 0,792 | 0,619 |
| CVR [%] | 1,48 | 4,69 | 4,11 | 4,22 |
number of laboratories submitting results
number of single results retained after eliminating outliers (identified by Cochran, Dixon outlier test)
standard deviation of repeatability
standard deviation of reproducibility
repeatability
reproducibility
coefficient of variation of repeatability, %
coefficient of variation of reproducibility, %