Abstract

A direct large volume injection (DI-LVI) high performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS) method was developed and validated for the quantitative determination of 16 systemic insecticides and their main plant metabolites. The assays were conducted on commercial red and white wines made from grapes grown in major wine-producing regions nationally and internationally. Using a 1:20 dilution and an injection volume of 800 mu L, a limit of quantitation (LOQ) of I mu g L-1 for all analytes was achieved. Matrix-matched standards (MM) were used for accurate quantitation. Imidacloprid (IMI) and methoxyfenozide (MET) were the most frequently detected parent insecticides in the wines reaching concentrations of 1-132 mu g L-1. Two important plant metabolites imidacloprid-olefin (IMI-OLE) and spirotetramat-enol (SPT-EN) were found at higher concentrations. In five samples SPT-EN was detected in the mg L-1 range with a maximum concentration of 16.3 mg L-1 measured in a conventional white wine sample. Most "organic" wines contained no detectable or low insecticide residues, except for one sample, which showed the highest IMI (14.7 mu g L-1) and IMI-OLE (331 mu g L-1) concentrations. Considering the maximum residue limit (MRL) definition for the different insecticides, three "conventional" wine samples were non-compliant for SPT. This study highlights the importance to determine both parent and metabolite forms of systemic insecticides in the finished product. (C) 2017 Elsevier B.V. All rights reserved.