Analytical utility of quadrupole time-of-flight mass spectrometry for the determination of pesticide residues in comparison with an optimized column high-performance liquid chromatography/tandem mass spectrometry method.

A multiresidue method for the analysis of 30 pesticides with different physicochemical properties in fruits and vegetables was developed. The method involves a rapid and small-scale extraction procedure based on matrix solid-phase dispersion using octadecylsilyl (C18) as the dispersant and dichloromethane as the eluent. The target pesticides were determined using column high-performance liquid chromatography/triple quadrupole-tandem mass spectrometry (LC/QqQ-MS/MS). The method was validated for sensitivity, linearity, reproducibility, and accuracy. A recovery study was conducted at 3 different levels, and the average ranged from 74 to 99% for all of the studied compounds, with relative standard deviations lower than 19%. The proposed method achieved limits of quantitation between 0.5 and 10 microg/kg, well below the maximum residue limits. The capability of the extraction procedure to extract pesticide residues other than those selected as target analytes has been checked by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/QqTOF-MS). Four incurred pesticides, not covered in the method as target analytes, were identified and unequivocally confirmed. Both systems were demonstrated to be complementary. LC/QqQ-MS/MS has the advantage that its detection limits are somewhat lower, and UPLC/QqTOF-MS offers the possibility to identify pesticides and transformation products not included as targets of the study.