Proficiency testing for the determination of pesticides in mango pulp: a view of the employed chromatographic techniques and the evaluation of laboratories' performance

Abstract

The proficiency testing for determination of pesticides residues in mango pulp was the third work of the partnership established by INMETRO and INCQS/Fiocruz. Three mango pulp samples were sent to each participant laboratory, two being spiked with the pesticides and one exempt of pesticides. The added pesticides were: deltamethrin, ethion, fenitrothion, malathion, and permethrin. The evaluation of the results of the homogeneity and the stability tests, as well as the determination of the assigned value was made in agreement with ISO GUIDE 35 and ISO 13528, assuming the samples were considered homogeneous and stable for the studied period. The assigned values and the standard deviation for proficiency evaluation was calculated using the robust algorithm, according to ISO 13528, and the evaluation of the results was carried through in accordance with ABNT ISO/IEC Guide 43-1. The z-score graphs and confidence ellipse was also used in the evaluation of the results. In the evaluation carried through from the values of the z-scores, 71% of the reported results were considered satisfactory based on the results found for this index. The evaluation of the analytical viability for the determination of each pesticide and of the analytical capacity of the participant laboratories was carried through. A summarized view of the chromatographic techniques and of preparation of sample used by the participant laboratories was also carried through in this work.