HTC-15 - Abstract

Abstract Information :

The objective of this research is to develop and validate chromatographic method for qualitative and quantitative determination of pesticides residues in vegetables and fruits and to establish acceptable QA/QC measures for the developed method. GC/MS and GC/MS/MS methods and techniques were developed for separation and quantification of ultra-low (ppb and sub-ppb) concentrations of more than fifty pesticides compounds. The method was developed primarily on Agilent GC 6/7890N and Agilent Model 5973 MSD quadrupole mass spectrometer operated in the electron impact mode at 70 eV and coupled with Agilent Model 6/7890 gas chromatograph, then later transferred to GC/MS/MS. The GC is equipped with a 30 m x 0.25 mm i. d. capillary column coated with DB-5 (Agilent, film thickness 0.25 µm). The GC is operated using a temperature program of 45°C hold for 2 min, ramp to 300°C at 5°C/min, and hold isothermal at 300°C for 30 min. Temperature program vary for each group of pesticides and accordingly. Helium is used as the carrier gas and the GC inlet is at 280oC. GC-MS data was acquired and processed with Agilent Mass-Hunter/ChemStaion™ software. Compounds are identified on SIM mode by GC retention indices, and by comparison of mass spectra with those of authenticated standards, by correlation with the literature or by interpretation of the mass spectrometric fragmentation pattern. The developed method was validated successfully and applied on tomato, cucumber and lettuce. Figures of merits including limit of detection, limit of quantification, recovery, reproducibility, repeatability are stablished. The developed method shows significant improvement of sensitivity and selectivity of some pesticides