Evaluation of large volume-difficult matrix introduction-gas chromatography-time of flight-mass spectrometry (LV-DMI-GC-TOF-MS) for the determination of pesticides in fruit-based baby foods

Abstract

The European Union Baby Food Directive (1999/39/EC), which came into force on 1 July 2002, set legal maximum residue levels at 0.01 mg kg−1 for all pesticides in baby foods. The combination of large volume-difficult matrix introduction (LV-DMI) with gas chromatography-time of flight-mass spectrometry (GC-TOF-MS), described herein, provides the analyst with a simple but rapid alternative GC-MS technique for the multiresidue analysis of pesticides in fruit-based baby foods. Samples were extracted with ethyl acetate in the presence of Na2SO4 and NaHCO3 and the crude extracts were analysed directly using LV-DMI-GC-TOF-MS. The best overall results (98 pesticides quantified satisfactorily at a spiking level of 0.01 mg kg−1) were obtained by analysis of concentrated extracts (2.5 g crop ml−1) using a 30-m column, with a chromatographic run time of 25 min. A good signal-to-noise ratio was obtained at the lowest calibrated level (0.0125 μg ml−1), with excellent linearity achieved over the range 0.0125–0.25 μg ml−1 (equivalent to 0.005–0.1 mg kg−1). Average recoveries for the analysis of five replicate determinations at a spiking level of 0.01 mg kg−1 were between 79 and 114% with relative standard derivations generally less than 20%.