Division 4.3.2.7 Continuous method verification/on-going method validationF1

After initial validation, additional validation data are acquired by including at least two positive control samples in each batch of samples screened. One positive control sample is a known sample (e.g. one used during initial validation), the other is a different commodity from the same commodity group (in case only one commodity is analysed, a different sample of that commodity is used instead). Inclusion of a negative control sample is optional. The results obtained for the two positive control samples are added to the existing validation set.

At least once a year the cut-off value is re-established and the validity of the method is re-assessed. The continuous method verification serves several purposes:

• quality control for the batch of samples screened

• providing information on robustness of the method at conditions in the laboratory that applies the method

• justification of applicability of the method to different commodities

• allowing to adjust cut-off values in case of gradual drifts over time.