Multiresidue method for fourteen fungicides in white grapes by liquid-liquid and solid-phase extraction followed by liquid chromatography-diode array detection

A quantitative, selective and sensitive HPLC method for the analysis of 14 fungicides in white grapes for vinification is described. The proposed method is based on liquid-liquid extraction (LLE) and solid-phase extraction (SPE) followed by liquid chromatography and diode array detection (HPLC-DAD). Dichloromethane-acetone (75:25, v/v) was the most appropriate solvent mix for extracting fungicides in white grapes. Silica cartridges resulted the most appropriate for extract purification purposes. Quality parameters of the proposed multiresidue method presented good recovery (ca. 85% for almost all target compounds) and precision (between 1.5 and 16%), and detection limits lower than maxima residual limits set by the 76/895/ECC and 90/642/ECC Directive. Five different white grapes for vinification produced in Rias Baixas area in Galicia (NW Spain) were analyzed in order to assess the performance of the method with real samples and to determine whether the concentration of the pesticides used exceed their maxima residue levels (MRLs). Results showed that grape concentrations for those identified fungicides were lower than those established by European legislation.