A rapid sensitive and selective GC-Ms/Ms method for multi residue analysis of a large number of pesticides in chamomile

Abstract

Multi-residue methods for pesticide residues analysis in herbal plants, using gas chromatography tandem mass spectrometry (GC-MS/MS), usually carried out by a long run time. These longer run times of analyses are performed to avoid the overlapping of the co-extracted natural components with the analyzed pesticides in herbal samples. In the current study, a rapid sensitive and selective GC-MS/MS method, of run time 25 m, has been developed for the analysis of 212 pesticides in chamomile. The oven temperature program has been optimized to give a better distribution for the eluted pesticides along all the run time. Besides, the back flush technique has been used to remove the less volatile compounds and to decrease the analysis runtime. In addition, the sample preparation was a modification of the known QuEChERS extraction method by applying a freezing step at -20 °C for 20 m before adding the salting out mixture. The developed method enables food safety laboratories to increase the number of analyzed samples per day with a reduction of the total analysis cost. The developed method has been fully validated on chamomile according to SANTE/11813, 2018. The obtained results showed that, more than 206 pesticides have average recoveries between 70-120 % at a concentration level of 50 μg kg-1. Limit of quantitation for 160 of the studied pesticides equal 10 μg kg -1. The developed method was also employed for the analysis of real chamomile samples collected from Al-Fayoum governorate, Egypt. The obtained results showed that most of the collected samples were positive by different pesticide residues. There were three samples contaminated by five to six different pesticides, indicating the presence of uncontrolled pesticide practices.