Determination of succinate-dehydrogenase-inhibitor fungicide residues in fruits and vegetables by liquid chromatography-tandem mass spectrometry

In recent years, a second generation of succinate-dehydrogenase-inhibitor (SDHI) fungicides has been introduced into the market for effective treatment of fruit and vegetable crops, with fluxapyroxad, boscalid, fluopyram, penflufen, bixafen, penthiopyrad, and isopyrazam being some of the members of this new class of agrochemical. We herein report the development of an analytical procedure for the determination of residues of these SDHI fungicides in food samples, based on a modification of the QuEChERS extraction method followed by ultra-performance liquid chromatography coupled to tandem-mass-spectrometry determination. The proposed method reached limits of detection from 0.8 to 2.0 mu g L-1. Apple, strawberry, tomato, and spinach samples were used as model samples. Spiked samples, from 10 to 1000 mu g kg(-1), were analysed by the proposed method and quantitative recoveries were obtained (from 81 to 115 % for apples, from 84 to 136 % for strawberries, from 84 to 135 % for tomatoes, and from 80 to 136 % for spinach), with precision better than 20 % in all cases. Thus, the proposed method can be used for the analysis of SDHI fungicide residues to efficiently ensure that marketed fruits and vegetables comply with the maximum residue levels established by competent authorities.