Documentation: Mycotoxin Scheme
For the Mycotoxin Scheme samples are carefully prepared by comminution and quantitatively blending a contaminated feed material with a feed matrix of interest. The finished bulk sample undergoes detailed Mycotoxin analysis by a reference lab including Homogeneity testing. It is then split and distributed to clients for their analysis.
When the program started the Assigned value was provided by a reference lab and not based on the consensus of participants. We quickly learned that the assigned value was occasionally quite far from the Consensus Value. At the 2015 mid year meeting in San Antonio it was agreed to use the Consensus Value as calculated using robust statistics. The fit-for-purpose standard deviation is derived from a modified Horwitz relationship. The following pdf presentation describes this statistical approach.
The following presentation describes the January 2015 protocol change to Consensus Value for determining Z scores.
Revised Mycotoxin Scheme.
Documentation: Mycotoxin Scheme, 2018 ffp sigma Modification
In reviewing Mycotoxin robust SDs over the last 3 years (2015 to Q1 2018, 13 samples) we find that even the Thompson modification of the Horwitz relationship does not hold true for our 50 clients. The observed robust SDs are severely underestimated by the Thompson modification and somewhat less by the original Horwitz relationship.
What follows is a description of a redesigned Horwitz like data fit for the AAFCO Mycotoxin Scheme.
At the 2018 annual AAFCO Meeting in Fort Lauderdale, the PT committee agreed to make the described changes starting with the 2018 third Quarterly Mycotoxin round.
Revised Mycotoxin ffp Sigma, 2018 Decision.
The Following are Examples of Available Reports pre 2020.
Example of a Mycotoxin Scheme Proficiency Test Report Card.
Mycotoxin Scheme Example of a Proficiency Testing Report.
Documentation: Mycotoxin Scheme, 2020 Revised Reporting.
At the 2020 Mid Year AAFCO meeting in Albuquerque, the PT committee agreed to moving Mycotoxin Scheme reporting to the same format as Animal Feed, Pet Food and Minerals Schemes reporting. We now have enough clients to warrant reporting individual method PT statistics. Also, uniform Scheme reporting provides for more facile accreditation review.
The Following slide presentation describes the new reports in some detail:.
New Mycotoxin Reports, January 2020 Presentation
All reports now appear as described in "Documentation: Examples" above. The 2018 revised ffp sigma is still in effect for Mycotoxins as described above.