Analysis of multiresidue pesticides in dried hops by LC-MS/MS using QuEChERS extraction together with dSPE clean-up
Abstract
A simple and selective method is reported for the simultaneous determination of 48 fungicide, insecticide and herbicide residues in hops by LC-MS/MS. The extraction of pesticide residues from the hop matrix was conducted by a method based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) sample preparation approach in combination with dispersive solid-phase extraction using various sorbent blends consisting of primary-secondary amine, C-18 and zirconia based sorbents.
The matrix effect of all applied sorbent blends was evaluated. The results showed that the QuEChERS method required further optimization of the dispersive solid-phase extraction cleaning step owing to co-extraction of matrix components such as chlorophyll and hop resins.
These contaminants resulted in signal suppression, elevated background, and other negative matrix effects. The accuracy, precision, specificity, linearity, limit of detection and limit of quantification were evaluated.
The recovery ranged from 70 to 120% for most of the pesticides and RSD was <20% for all pesticides. The limit of quantification was estimated at 0.02mg/kg or, in the worst cases, 0.05mg/kg.
The results meet the European Commission standard legislation, implying that this method is both accurate and reproducible.