Report on the 2016 proficiency test of the European Union reference laboratory for mycotoxins for the network of National Reference Laboratories : determination of aflatoxin B1 in defatted peanut powder

The Joint Research Centre (JRC), a Directorate-General of the European Commission, operates the European Union Reference Laboratory (EURL) for Mycotoxins. One of its core tasks is to organise proficiency tests (PTs) among appointed National Reference Laboratories (NRLs). This report presents the results of the PT on the determination of aflatoxins in defatted peanut powder. The test items for this PT were two contaminated defatted peanut powder samples. The materials were produced by the JRC and dispatched to the participants mid October 2016. Each participant received one bottle per test material containing approximately 55 g each. Fifty-six participants from thirty countries (among them 40 NRLs and 16 official food control laboratories) registered for the exercise and 54 sets (Sample A and B) of results were reported. The assigned values, established by an exact-matching double isotope dilution mass spectrometric technique, were 2.80 μg/kg (± 0.19 μg/kg) aflatoxin B1 in sample A and 3.20 μg/kg (± 0.20 μg/kg) in sample B. Participants' results were rated with z-scores and zeta-scores for aflatoxin B1 in accordance with ISO 13528:2015. The z-score compares the participant's deviation from the reference value with the target standard deviation accepted for the PT, whereas the zeta-score provides an indication of whether the participant's estimate of uncertainty is consistent with the observed deviation from the assigned value. Only z-scores were used for the evaluation whether an individual laboratory underperformed. In total, 96 % of the attributed z-scores were below an absolute value of two for sample A and and 92 % for sample B. This indicates that most of the participants performed satisfactorily. The few participants that had z-scores above an absolute value of 2 will have to investigate the reasons for the deviation (root-cause analysis) and report the planned corrective actions to the EUR.