One-year routine application of a new and rapid method based on ultra performance liquid chromatography-tandem mass spectrometry to the analysis of selected pesticides in citrus fruits.

A rapid method has been developed for monitoring five multiclass pesticides commonly used in citrus fruits. The determination is performed by ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), after extraction with a mixture of ethyl acetate and sodium sulfate. The method has been validated for orange matrix. Mean recoveries obtained were between 74-110% with a repeatability precision of < 7%, intermediate precision of < 10% and reproducibility precision of < 17%. Linearity over the range 0.010-0.150 mg/kg was demonstrated (r(2) > or = 0.99) with limits of quantification (LOQs) of < or = 0.01 mg/kg. Also, an analytical study focused on the stability of pesticide residues in orange extracts under storage was performed. The method has been applied to the analysis of 365 samples from the agricultural area of the Valencian Community (Spain). Of 103 samples that contained pesticide residues, only abamectin in 2 samples and carbendazim in 5 samples slightly exceeded the European maximum residue limits (MRLs).