Simultaneous determination of sulfonylurea herbicides in tomatoes using the QuEChERS method coupled with HPLC

Abstract

The simultaneous determination of trace pesticides in complex matrices containing high concentrations of natural pigments remains challenging. In this study, quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation together with high-performance liquid chromatography with ultraviolet detection (HPLC–UV) was applied for the multi-residue analysis of seven sulfonylurea herbicides (SUHs) in tomatoes. SUH residue was extracted using the QuEChERS procedure, followed by solid-phase extraction (SPE) and dispersive SPE (d-SPE). To reduce the amount of carotenoids in tomato extracts, several d-SPE clean-up procedures were compared, and octadecylsilane (C18) provided the best color removal rate (%) of tomato extracts and recoveries (%) for all the tested SUHs. The validation results indicate good linearity (R2 > 0.9970), accuracy, and precision. Recoveries of 70–120% and relative standard deviations < 20% were achieved for all analytes at three spiked concentrations. The limits of detection and quantification for the 7 SUHs were 0.003 mg kg−1 and 0.008–0.009 mg kg−1, respectively. The developed method was subsequently used to quantify multi-residue SUHs during real sample analysis. None of the tested samples had SUH residue levels higher than the maximum residue limits established by the Korean Ministry of Food and Drug Safety. The results suggest that QuEChERS sample preparation employing a combination of C18 is a high-throughput and rapid clean-up procedure for the multi-residue analysis of SUHs in tomatoes.