This Application Note describes an UHPLC/Q-TOF/MS method for screening 240 pesticides and pesticide metabolites in difficult food matrixes. The method benefits from increased chromatographic resolution using the Agilent 1290 Infinity UHPLC System and improved ionization capabilities with an Agilent Jet Stream ionization source. More importantly, the successful screening of analytes is accomplished by the innate sensitivity improvement of the Agilent 6545 Q-TOF LC/MS System and ion transmission tuning to facilitate the optimal ion transmission of small, fragile organic molecules. Targeted MS/MS acquisition was used for analyte quantitation and confirmation. Black tea matrix was chosen for its complexity, and avocado matrix was chosen to represent food commodities with high lipid content. Our results demonstrate that the improved detection of small organic molecules by the 6545 Q-TOF LC/MS System allows the screening and quantitation of most of the targeted pesticides below the maximum residue limits (MRLs) specified by the European Commission regulations. 6500 系列四極桿(Q-TOF) 液質(zhì)聯(lián)用系統(tǒng)