Determining the residue of 198 different pesticides in various types of dates available in the Iranian market with the modified QuEChERS extraction method and gas chromatography tandem mass spectrometry

The aim of this study was to develop a convenient, fast, effective and safe analytical method (QuEChERS) to determine 198 pesticide residues in date palm using gas chromatography-tandem mass spectrometry (GC/MS/MS). Extraction was performed with acetonitrile as the extracting solvent, magnesium sulfate in the presence of sodium chloride as the dehydration reagent, and PSA as purification phase to remove non-polar interfering substances such as lipids For this purpose, the effect of two affecting variables including extraction time and the volume of added water to the sample was investigated. To solve the effect of the matrix, the calibration curve was plotted using the analysis of spiked samples by dividing the peak area of the pesticides to the the peak area of the internal standard. The calibration curves for most pesticides were linear in the range of 15–150 μg/kg, with r2 values higher than 0.9934 and the relative standard deviation for all pesticides was ≤20%. The mean recovery rate of pesticides was 70-120% and limits of detection (LODs) and limits of quantification (LOQs) were in the range of 5–14 μg/kg and 14–40 μg/kg, respectively. The validated procedure was used to monitor pesticide residues in 30 fresh date samples. It can be concluded that the modified QuEChERS extraction method was efficient in analyzing pesticide residues in dates palm and none of the samples contained residues above the( Maximum Residue Limit) MRLs.