Laboratory performances during proficiency tests for the analysis of active substances in pesticide formulations during 2021–2023

During the period 2021–2023, the Italian National Institute of Health (ISS) organised, in collaboration with the Italian Health Ministry, proficiency testing (PTs) for about 22 Italian and other EU laboratories involved in the monitoring programmes for Plant Protection Products (PPPs). The aim of the PTs was to determine the amount of active ingredient in various formulations of PPPs. Overall, the type of formulations to be analysed were soluble concentrate (SL), suspension concentrate (SC), capsule suspension (CS), emulsion water oil (EW), soluble water granule (SG), dustable powder (DP), water dispersible granule (WDG) and emulsion concentrate (EC). In 2021, the ISS organised PTs for the determination of Imazamox, Fenhexamid and Trinexapac-ethyl in three different PPPs as soluble concentrate (SL), suspension concentrate (SC), and capsule suspension (CS), respectively. In 2022, PTs for the determination of Bentazone, Spinosad and Tau-Fluvalinate were organised. For this PTs, commercial PPPs were obtained from the Italian market as SC, emulsion oil water (EW) and soluble water granule (SG). In 2023, the PT was organised to determine the active ingredient Trifloxystrobin, Deltamethrin and Cyprodinil in the commercial product as water dispersible granule (WDG), dustable powder (DP) and emulsion concentrate (EC), respectively. Homogeneity and stability, performed for all PT samples, fulfilled the acceptability criteria. The Jarque–Bera test was used to verify the hypothesis of normality of the data distributions before to calculate the z-score values. Laboratory performances, expressed in terms of z-scores, were satisfactory for almost all participants for all substances.