The monitoring of food quality and safety requires a suitable analytical method with simultaneous detection in order to control pesticide and herbicide residues. In this study, a novel analytical method, referred to as "dispersive solid-liquid extraction", was applied to monitor seven sulfonylurea herbicides in strawberries. This method was optimized in terms of the amount of C18 and the volume of added water, and it was validated through satisfactory linearities (R2 > 0.99), recoveries of 70% to 84% with acceptable precisions, and limits of quantification lower than the maximum residue limits for the seven sulfonylurea herbicides in strawberries. The cleanup efficiency of the dispersive solid-liquid extraction technique was compared to that of the QuEChERS- ("quick, easy, cheap, effective, rugged and safe") based method with dispersive solid phase extraction. The recoveries of the former were found to be comparable to those involving QuEChERS C18 cleanup (recoveries of 74%-87%). The method was used to determine sulfonylurea herbicide residues in ten strawberry samples. None of the samples had herbicide residues higher than that of limit of quantifications (LOQs) or maximum residue limits (MRLs). The results suggest that the dispersive solid-liquid extraction method combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) is effective for the analysis of sulfonylurea herbicide residues in strawberries.
Keywords: QuEChERS; cleanup; dispersive solid-liquid extraction; strawberry; sulfonylurea herbicides.