Large-scale multi-residue methods for pesticides and their degradation products in food by advanced LC-MS

Pesticide testing in foodstuffs is a challenging application for mass spectrometry (MS), since it implies simultaneous trace analysis of hundreds of compounds belonging to a many classes, preferably undertaken in one fast run. The appearance and the use of new, more polar pesticides has prompted the use of liquid chromatography electrospray ionization MS (LC-ESI-MS) instead of gas chromatography. Currently, large-scale multi-residue methods (LSMRMs) (i.e. covering over 80 analytes) for pesticide analysis are developed using LC with tandem MS (LC-MS2) with triple quadrupole mass analyzers or LC with time-of-flight MS (LC-TOF-MS).The present article provides a review of the most significant MRMs for determining pesticide residues in foodstuffs. We discuss the main features of LC-MS2and LC-TOF-MS instruments, including recently introduced advances in instrumentation. In addition, we describe the advantages and the pitfalls of these methods, together with examples of the application of LC-TOF-MS and LC-MS2 to large-scale screening, identification and quantitation of pesticides in foodstuffs.