UNE-EN ISO/IEC 17025:2005 accredited method for the determination of 121 pesticide residues in fruits and vegetables by gas chromatography–tandem mass spectrometry

A rapid, sensitive, accurate and reliable multiresidue method for quantification and confirmation of 121 common agricultural pesticides in fruits and vegetables by gas chromatography in tandem with mass spectrometry was developed, validated and applied to 1463 vegetable and fruit samples collected over one year from extensive greenhouse cultures in Almería (Spain). Prior to instrumental analysis an extraction procedure, based on a sample extraction of multi-class analytes according to QuEChERS method (quick, easy, cheap, effective, rugged and safe) with some modifications was used. Mass spectrometric conditions were individually optimized for each analyte to achieve maximum sensitivity in the Selected Reaction Monitoring (SRM) mode. The scan times for each segment were between 0.8 and 1.0 s, with a maximum of 35 transitions per segment. Use of two reactions for each pesticide allowed simultaneous quantification and identification in one run. The pesticides were separated in less than 30 min. Recovery and precision were evaluated in nine representative matrices (tomato, pepper, lettuce, cucumber, eggplant, zucchini, melon, watermelon and apple). The mean recoveries ranged from 80% for thiometon to 116% for heptenophos, with relative standard deviations lower than 20% for all components. Only three pepper samples, one of tomato and one of cucumber had residues above the maximum allowable residue (0.01 mg kg−1) according to European Union directives. The method was accredited according to UNE-EN ISO/IEC 17025:2005 international standard.