ANALYTICAL METHODS for determining the presence of a group of 100 pesticides in vegetable and fruit samples were developed using a time -of -fl ight mass spectrometer (LC/TOF -MS) and a triple quadrupole mass spectrometer (LC/ MS/MS) and the two methods were compared. The sensitivity of the LC/TOF -MS was determined in food matrices of orange, tomato, and green pepper using accurate mass in full scan. For the LC/MS/MS, two transitions per parent compound were monitored in a single chromatographic run containing two time segments. The sensitivity obtained meets the maximum residue levels (MRLs) established by the European Union regulation for food monitoring programs. Likewise, this study is a valuable indicator of the potential of both the LC/TOF -MS and the LC/MS/MS for routine quantitative multi -residue analysis of pesticides in vegetables and fruits and discusses the limit -of -detection or " crossover point, " which is the point where the sensitivity of the LC/TOF -MS and the LC/MS/MS are approximately equal for 50% of the compounds. Beyond this point the LC/TOF -MS becomes more practical for pesticide screening as the sensitivity is greater for the majority of compounds.