Multiresidue method for the analysis of more than 140 pesticide residues in fruits and vegetables by gas chromatography coupled to triple quadrupole mass spectrometry

A new multiresidue method has been developed and validated for the determination of more than 140 pesticide residues in cucumber and orange by gas chromatography coupled to triple quadrupole mass spectrometry GC–QqQMSMS in a single run of 25.50 min. The triple quadrupole QqQ analyzer simultaneously operated in the selected reaction monitoring SRM and selected ion monitoring SIM modes, acquiring two or three transitions per compound. Samples were extracted by the application of a singlephase extraction of 10 g of sample with acetonitrile containing 1 of acetic acid, followed by a liquid–liquid partition formed by the addition of 4 g of MgSO4and 1 g of NaOAc. A dispersive solidphase extraction DSPE with primary secondary amine PSA was applied to clean up the extracts. A final concentration step was included in order to increase sensitivity in the instrumental analysis. The method was properly validated in each matrix in a wide dynamic range 10–400 µg kg−1: this work relies on a new quantification strategy by the use of two calibration curves to increase the dynamic range, which permitted reduction of sample dilutions and increase in sample throughput. Recovery was studied at three concentration levels 11.5, 50.0, and 150.0 µg kg−1, yielding values in the range 70–110 with precision values, expressed as relative standard deviation RSD, lower than 20 and 25 for the intraday and interday precision, respectively. Limits of quantification LOQs were established at 10 µg kg−1, the lowest maximum residue level MRL value set by the European Union in vegetables. The method was successfully applied to the analysis of pesticide residues in real samples from the southeastern Spain. Copyright © 2008 John Wiley & Sons, Ltd.