Uncertainty of sampling, homogenisation & analysis

The aim of the method ring test is

• a real-world assessment of the uncertainty of sampling from the fruit crate to the analytical sample in accordance with the Eurachem guidelines,
• the evaluation of the performance of the labs with respect to the homogenisation of the samples, and
• the evaluation of the analytical performance of the labs with respect to the quantification incurred residues of typical pesticides in grapes.

Whole fresh grapes with incurred residues as well as a homogenate, prepared of the same grapes are provided.

PROOF-ACS, as the organiser, carries out a standardised practical sampling of the laboratory samples from the fruit crates. The laboratory samples are provided to the participants, two samples for each lab. In addition, a homogenate, prepared of a sample of all fruit crates is provided to derive the analytical uncertainty for the respective pesticides and the participating laboratories.

The participants are requested to

• homogenise the samples in accordance with a guideline provided by PROOF-ACS, and to provide a photo documentation of the process of the homogenisation.
• analyse all 4 sub-samples, 2 for each non-homogenised material for pesticide residues (multi-residue methods).
• analyse the homogenate as provided by PROOF for pesticide residues (multi-residue methods).