Multiresidue Determination and Uncertainty Analysis of Pesticides in Soil by Ultrafast Liquid Chromatography Coupled to Mass Spectrometry

This work presents the validation results of a simple, fast and low-cost sample preparation method for the determination of pesticide residues in soil by ultrafast liquid chromatography coupled to electrospray ionization mass spectrometry. The method uses acetonitrile ultrasound-assisted extraction, centrifugation and evaporation step, without further cleanup. Recovery studies were performed for two soil blanks, presenting results in the range of 70-110% with relative standard deviation lower than 20%. The correlation coefficients for analytical calibration curves were higher than 0.99. Pesticide residues were detected in soils in the range of 1-62 ng g(-1), depending on the compound. The uncertainty of the method was estimated from different addition-recovery experiments and calculations from certificates. The extraction process was identified as the main source of uncertainty, and the expanded uncertainties for each pesticide, using a coverage factor of two, were between 8.4 and 33%. The proposed method was applied to the determination of pesticides in real samples.