A rapid and reliable method for the determination of 10 pesticide residues in coconut (Cocos nucifera L.) tree trunks after endotherapy treatments has been established. A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, using an homogeneous sample slurry and acetate buffer, followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. Under the best extraction conditions, the average recoveries for all pesticides spiked at 40, 80 and 200 mg kg À1 ranged from 70 to 93%, with RSD <10%. Intermediate precision expressed as RSD, ranged between 3 and 6% for all compounds. Calibration curves showed a wide linear range between 10.0 and 1000.0 mg kg À1 for all compounds studied. Limit of quantification was established as 40.0 mg kg À1 . The developed procedure was employed in the analysis of real coconut tree trunk samples obtained 45 h after pesticides application using endotherapy treatment.Concentrations of pesticides were between 44.7 AE 5 and 938.3 AE 20 mg kg À1 . These results prove the translocation of pesticides in different heights, in the coconut tree trunk, from the application point. Imidacloprid presented the highest acropetal translocation and was found near the leaves at 61 AE 6 mg kg À1 .

A modified QuEChERS method was optimized for pesticide multiresidue extraction from maize for further GC-MS/MS determination.

Pollution of water sources by pesticides is a result of intensive use of these compounds, and the establishment of analytical methods for monitoring programs is very important. This paper presents a method for the determination of multiclass pesticide residues in rice paddy water based on SPE and GC/MS/MS. The validation results were satisfactory. All compounds showed adequate linearity (r2 >or= 0.99), and analysis by GC/MS/MS with a triple quadrupole mass spectrometer gave high selectivity and sensitivity. With the proposed SPE step an LOD of 0.06 microg/L was achieved. Recoveries from blank samples spiked at 0.2, 04, and 0.8 microg/L were between 70 and 120% with RSD <20% for most analyzed compounds, despite their different chemical nature, indicating good accuracy and precision. The proposed method is efficient for pesticide residue determination, including some metabolites, and gave good performance when applied to real samples.