Determination of 250 pesticide residues in the Iranian vegetables assessed during 2019–2020 using the modified QuEChERS method along with gas chromatography - mass spectrometry

Abstract

In this study, association of official agricultural chemists(AOAC) international (2007) QuEChERS (quick, easy, cheap, effective, rugged,and safe) method was developed with slight changes under the term of the modified QuEChERS method and was used along with gas chromatography–mass spectrometry (GC–MS) for determination of 250 selected multiclass pesticides in vegetables (in total of 1436 samples) during 2019 - 2020 in iran. The principles of this method are similar to the conventional QuEChERS method and involve extraction of acetonitrile, followed by the dispersed solid-phase extraction (SPE) purification with a combination of primary-secondary amine (PSA) adsorbent and MgSO4 but with slight changes in steps of sample preparation and volume of organic solvent and amount of adsorbent. For performance evaluation, validation method was carried out. After applying changes and experiments, recovery yields ranged from 77.1 to 113.2%, with repeatabilities of 4.4–19.2%. The limits of detection (LODs) were between 0.0016 - 0.044 for target analytes in extract of vegetable samples. The expanded measurement uncertainty was not higher than 30% for all target analytes. The method was successfully applied for analysis of 1,436 vegetable samples obtained from local markets and vegetable traders. There were no residues in 69.76% of samples. A portion (25.49%) of the samples contained pesticide residues less than or equal to the maximum residue limits (MRLs), and 4.94% of samples contained pesticide residues greater than their MRLs. Our findings provided useful information on the current contamination status of a key agricultural area in iran from 2019 to 2020 and highlighted the need for regular monitoring of pesticide residues in a greater number of vegetable samples for longer periods.