Investigation of pesticide residues in apple fruits from conventional and integrated pest management
International audience ; This study describes method validation for determination of more than 40 pesticides in apples using GC technique. Target compounds belong to the groups of organochlorine, organophosphorus, carbamates, pyrethroids, triazoles, dicarboximides, strobilurins etc. The sample preparation consists of acetone extraction and subsequent cleanup/concentration by SPE with polymer-based sorbent. Single quadrupole GC-MS operating in SIM mode and electron impact ionization was used for identification and quantification of the pesticides. The average recoveries obtained for analytes ranged between 70 and 110 % at three fortification levels - 0.01, 0.1 and 0.2 mg kg-1. The relative standard deviation was lower than 20 % for all tested compounds. The calculated limits of detection and limits of quantification were below 0.01 mg kg-1 which were sufficiently low compared to the maximum residue levels (MRLs) established by European legislation. The proposed method was applied for determination of pesticide residue in four selected apple varieties after harvesting. Whole and processed fruits (peels and peeled fruits) were analyzed from different schemes of treatment: two conventional, one based on integrated pest management (IPM) and two variants based on organic production (controls). Higher level of pesticide residues were found in apple fruits under conventional conditions. Fenitrothion and chlorpyrifos residues were detected frequently in apple peels at concentrations up to 0.45 and 0.77 mg kg-1, respectively. The levels found in the whole fruits of the same samples were much lower than in peels and below the respective MRLs (0.5 mg kg-1 for both pesticides). In the apples from IPM were found only measurable residues of triadimenol, concentrated in the peels up to 0.05 mg kg-1.