Determination of fungicides in wine by mixed-mode solid phase extraction and liquid chromatography coupled to tandem mass spectrometry

A novel procedure for the determination of nine selected fungicides (metalaxyl-M azoxystrobin myclobutanil flusilazole penconazole tebuconazole propiconazole diniconazole and difenoconazole) in wine samples is presented Sample enrichment and purification is simultaneously performed using mixed-mode anion exchange and reversed-phase OASIS MAX solid-phase extraction (SPE) cartridges Analytes were determined by liquid chromatography coupled to tandem mass spectrometry using atmospheric pressure electrospray ionization (LC-ESI-MS/MS) Parameters affecting the chromatographic determination and the extraction-purification processes were thoroughly investigated Under optimized conditions 10 mL of wine were firstly diluted 1 1 with ultrapure water and then passed through the mixed-mode SPE cartridge at a flow of ca 5 mL min(-1) After a washing step with 5 mL of an aqueous NH4OH solution (5% w v) analytes were recovered with just 1 mL of methanol and injected in the LC-MS/MS system without any additional purification The selective extraction process avoided significant changes in the ionization efficiency for red and white wine extracts in comparison with pure standards in methanol Performance of the method was good in terms of precision (RSDs <11%) and accuracy (absolute recoveries >72% determined against pure standards in methanol) reporting method LOQs in the range of 0 01-0 79 ng mL(-1) for target compounds which are far below the EU maxima residue levels (MRLs) for fungicides in vinification grapes and wine Several commercial wines from different geographic areas in Spain were analyzed In most samples metalaxyl-M and azoxystrobin were found at concentrations up to several ng mL(-1) (C) 2010 Elsevier BV All rights reserved