Thesis (Ph.D.) - Cairo University - Institute of African Research and Studies - Department of Natural Resources

Food safety is a high priority for human health. The multi-residue method of analysis for the determination of 323 pesticides in dry herbal products (chamomile and parsley) was developed as a target to improve products safety. The method has been optimized and validated using quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method followed by liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) determination. The chosen pesticides belong to various chemical groups; they are registered in Egypt or most frequently detected in crops in the Egyptian market. The parameters of the triple quadrupole mass spectrometer (decluster potention and collesion energy) were optimized to gain maximum sensitivity. Method development was divided into three parts; extraction efficiency, clean up trails and matrix effect study. The extraction tests supported the use of a mechanical shaker in comparison with ultrasound and hand shaking. As a way to remove an interfering component from final extract, two different cleanup techniques were studied. Three matrix solid phase dispersion (C18, PSA, and GCB) were tested and evaluated. The obtained results showed limited number of pesticides covered. While the solid phase extraction (HLB) produced a good recovery with all substances without expecting reduction in matrix effect

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