The EURL Anses-Fougeres provides PT for NRLs in charge of antibiotic residues in food from animal origin.

Surplus test materials from the batches used for the previous PT may be available for purchase as quality control (QC) samples for some analyte/matrix combinations.
These QC samples may be used for troubleshooting poor performance in the PT, training of new staff, method development or generating QC charts. The stability assessment of these QC samples is the same as the one carried out during the PT. No complementary stability testing is performed after the end of the PT even though the QC samples are kept frozen at -20°C for several months/years. Therefore the announced concentration is the consensus assigned value  measured during the PT.