Investigation on the Impact of QuEChERS and GCMS/ MSTQD as Multiresidues Techniques for Determination of 74 Pesticides in Olive Farm Soil

The extraction and analytical multiresidue method, has been developed and validated for quantification of trace levels of 74 pesticide belong to different chemical groups in organic and conventional Olive farm soil samples (Old, medial and new olive farms which is 25, 15 and 5 years respectively). Soil samples collected from Al-Jouf Province, Saudi Arabia, and extracted by Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) and analyzed by Gas Chromatography Mass Spectrometry Triple Quadrupole (GC-MS/MSTQD). The method reveals that experimental results were highly satisfactory in respect of various analytical parameters such as linearity, recovery and precision especially with the tested soil samples which is are complex matrixes, preparation is a critical step, and one that is usually expensive, time-consuming, and labor intensive. The limit of detection (LOD) and limit of quantification (LOQ) for the analyzed pesticides were in the range of 1.01-13.91 μg kg-1 and 3.02 - 29.15 μg kg-1, respectively. Pesticide recoveries form spiked soil samples with different pesticides ranged from 65.5 to 111.7%. The proposed method featured good sensitivity, pesticide quantification limits were low enough, and the precision, expressed as relative standard deviation, ranged from 0.29 to 13.32%. Pesticide residues being detected by applying the modified QuEChERS and GCMSMSTQD method, the levels were ranged from 43.00 to 2.00 μg kg-1 for 18 different pesticides, 1.99 to 1.00 μg/kg-1 for 16 different pesticides, 0.99 to 0.50 μg/kg-1 for 12 different pesticides and lower than 0.50 μg kg-1 for 28 different pesticide residues. The proposed QuEChERS and GC-MS/MSTQD method were applied successfully for the residues extraction and determination the 74 pesticides.