Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices.

Analysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid-phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi-class pesticide residues methods in various sample matrices. MS detectors-triple quadrupole (QqQ), ion-trap (IT), quadrupole linear ion trap (QqLIT), time-of-flight (TOF), and quadrupole time-of-flight (QqTOF)-have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra-performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed "ambient-ionization" MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high-resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre-treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysis.

Determination of multi-class pesticides in wines by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

This work reports a new sensitive multi-residue liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for detection, confirmation and quantification of forty-six pesticides and transformation products belonging to different chemical classes in wines. The proposed method makes use of a solid-phase extraction (SPE) procedure with Oasis HLB cartridges that combines isolation of the pesticides and sample clean-up in a single step. Analysis is performed by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-MS/MS) operated in the selected reaction monitoring (SRM) mode, acquiring two specific precursor-product ion transitions per target compound. An investigation of matrix effects has been performed during method validation showing medium to low effects for the majority of the compounds. Limits of detection (LODs) were in the range 0.0003-0.003 mg L(-1) and limits of quantification (LOQs) were in the range 0.001-0.01 mg L(-1). The average recoveries, measured at two concentration levels (0.010 and 0.050 mg L(-1)), were in the range 70-110% for most of the compounds tested with % relative standard deviations below 20%, while a value of 0.010 mg L(-1) has been established as the method limit of quantification (MLOQ) for all target species. Expanded uncertainty values were in the range 10-40% while the Horrat ratios were below 1. The method has been successfully applied to the analysis of 60 wine samples in the course of an annual monitoring study with carbendazim-benomyl, thiophanate-methyl and carbaryl being the most frequently determined pesticides.

Development and validation of a multi-residue method for the determination of pesticides in processed fruits and vegetables using liquid chromatography-electrospray ionization tandem mass spectrometry.

A sensitive multi-residue analytical method, utilizing ethyl acetate extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS), has been developed and validated for simultaneous determination of 28 pesticides of different chemical classes (polar organophosphates, carbamates, strobilurines, neonicotinoids, amides, pyrimidines, benzimidazoles, imidazoles and triazoles), and their transformation products, in processed fruit and vegetables. Two precursor-product ion transitions were monitored for each pesticide in selected reaction monitoring (SRM) mode. Linearity (r (2) > or = 0.99) was good over the concentration range 0.5 to 100 microg L(-1) for all the pesticides, and instrumental detection limits ranged from 0.1 to 1 microg L(-1). Mean recovery for fruit and vegetables spiked at 0.010 mg kg(-1) ranged from 65 to 94.4%, and relative standard deviations ranged from 9.0 to 20.0%. When the amount spiked was 0.050 mg kg(-1) recoveries ranged from 72.5 to 90% and relative standard deviations were from 6.1 to 19.0%. Method detection limits were from 0.002 to 0.007 mg kg(-1) for the different food matrices studied. The method was used to monitor pesticide residues in a wide variety of fruits and vegetables.