Monitoring of multi-class pesticide residues in fresh grape samples using liquid chromatography with electrospray tandem mass spectrometry

A sensitive and selective liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method was developed for the routine analysis of 10 multi-class pesticides residues (imidacloprid, thiamethoxam, chlorpyrifos, dimethoate, monocrotophos, metalaxyl, methomyl, hexaconazole, myclobutanil, carbendazim) in fresh grape samples. A miniaturized extraction-partition procedure that requires small amounts of non-chlorinated solvents was used. The extracts were analyzed by LC-ESI-MS-MS without any further cleanup step. The pesticides are separated on a reversed phase non-polar column using a gradient elution. Mean recoveries obtained at fortification levels of 0.010-0.100 mg/kg were 78-104% for all compounds, with relative standard deviations (RSDs) of <= 15%. The LC-MS-MS method allowed sensitive and selective quantification and identification at low levels in different matrices. The method was applied for analysis of fresh grape samples collected from an agricultural area in Hyderabad, South India. The results revealed that the concentrations of studied pesticide residues in grape samples were in the permissible limits except monocrotophos. (C) 2007 Elsevier Ltd. All rights reserved.