Application of solid-phase extraction and liquid chromatography-mass spectrometry to the determination of neonicotinoid pesticide residues in fruit and vegetables

A rapid and simple method for simultaneous analysis Of four neonicotinoid insecticides including acetamiprid, imidacloprid, thiacloprid and thiamethoxam in fruit and vegetable matrices has been developed. For instance, ready-to-use cartridges filled with a macroporous diatomaceous material were used to extract in a single step insecticide residues with dichloromethane from aqueuos-acetone extracts of fruits and vegetables. The eluate was evaporated, the residue redissolved with methanol and then analyzed by liquid chromatography-mass spectrometry in the electrospray ionization (ESI) positive mode. Average recoveries of the four pesticides were between 74.5 and 105% at both spiking levels 0.1 and 1.0 mg kg(-1) in peach, pear, courgette, celery and apricot. Relative standard deviations (RSDs) were less than 10% for all of the recovery tests. The calculated limits of quantitation (LOQs) (0.1-0.5 mg kg-1) were equal or lower then the maximum residue limits (MRLs) established by European legislation (0.1-0.5 mg kg-1). The proposed method is fast, easy to perform and could be utilized for monitoring of pesticides residues. (c) 2006 Elsevier B.V. All rights reserved.