Optimization and validation of a simple and fast method for the determination of fungicides in must and wine samples by SPE and GC/MS

Resum

A rapid, simple, and low-cost method based on SPE was optimized and validated for simultaneous determination of eight fungicides belonging to different chemical classes in must and wine. The method involves extraction of 10 mL of must or wine samples with a C18 cartridge using 5 mL of dichloromethane as the elution solvent. Separation and final determination of the fungicides (vinclozolin, dichlofluanid, penconazol, captan, quinoxyfen, fluquinconazol, boscalid, and pyraclostrobin) was performed by GC coupled to single quadrupole MS. Recoveries at 10, 50, and 100 μg/L were between 71 and 106% in both matrixes for the fungicides evaluated. The calculated LOQ ranged from 1.5 to 3.4 μg/L in must and 1.1 to 3.8 μg/L in wine. Matrix effects observed for wine and must samples were overcome by using matrix-matched calibration. The developed method was linear at concentrations within the tested interval, with coefficients of determination higher than 0.999. The expanded uncertainties at 10 μg/L were <20% for all analytes. Intralaboratory precision in terms of the Horwitz ratio of the fungicides evaluated was below 0.5, suggesting the ruggedness of the method. The proposed method was applied to determine fungicide residues in must samples obtained from red grapes treated with two new commercial formulations, as well as in their corresponding final wines.