This Application Note describes a UHPLC/Q - TOF/MS method for the detection of 240 pesticides and pesticide metabolites in diffi cult food matrixes using the Agilent All Ions MS/MS technique. The method benefi ts from increased chromatographic resolution using the Agilent 1290 Infi nity UHPLC system and improved ionization capa bilities with Agilent Jet Stream ionization source. More importantly, the successful screening and quantitation are accomplished by the innate sensitivity improvement of the Agilent 6545 Q - TOF LC/MS system and ion transmission tuning to facilitate the o ptimal ion transmission of small fragile organic molecules. The All Ions MS/MS technique features the easy acquisition method setup and retrospective data interrogation with expanded library. Black tea matrix was chosen for its complexity, and avocado m atrix 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 pesticid es below the maximum residue limits (MRLs) specifi ed by regulations Agilent 6545 四極桿飛行時間液質聯(lián)用系統(tǒng)