Application of gas chromatography–(triple quadrupole) mass spectrometry with atmospheric pressure chemical ionization for the determination of multiclass pesticides in fruits and vegetables

• A GC–(APCI) MS/MS quantitative method has been developed for 142 pesticides.
• Validation was performed using orange, tomato and carrot samples.
• SRM method includes the quasi-molecular ion as precursor for most compounds.
• The new APCI source coupled to GC allowed reaching high sensitivity and selectivity.
• LODs in the range 0.01–1 μg/kg were obtained for most compounds.

A multi-residue method for the determination of 142 pesticide residues in fruits and vegetables has been developed using a new atmospheric pressure chemical ionization (APCI) source for coupling gas chromatography (GC) to tandem mass spectrometry (MS). Selected reaction monitoring (SRM) mode has been applied, acquiring three transitions for each compound. In contrast to the extensive fragmentation typically obtained in classical electron ionization (EI), the soft APCI ionization allowed the selection of highly abundant protonated molecules ([M+H]+) as precursor ions for most compounds. This was favorable for both sensitivity and selectivity. Validation of the method was performed in which both quantitative and qualitative parameters were assessed using orange, tomato and carrot samples spiked at two levels, 0.01 and 0.1 mg/kg. The QuEChERS method was used for sample preparation, followed by a 10-fold dilution of the final acetonitrile extract with a mixture of hexane and acetone. Recovery and precision were satisfactory in the three matrices, at both concentration levels. Very low limits of detection (down 0.01 μg/kg for the most sensitive compounds) were achieved. Ion ratios were consistent and identification according to EU criteria was possible in 80% (0.01 mg/kg) to 96% (0.1 mg/kg) of the pesticide/matrix combinations. The method was applied to the analysis of various fruits and vegetables from the Mediterranean region of Spain.