A vortex-assisted liquid-liquid extraction followed by dispersive-solid phase extraction (VA-LLE/d-SPE) for the determination of eight benzoylphenylureas insecticides in tomatoes and cucumbers

Abstract

Monitoring benzoylphenylureas (BPUs) residues in ready-to-eat vegetables is of great interest for an adequate assessment of human pesticide exposure. A rapid, inexpensive, simple, and effective method for determining 8 BPUs insecticides in tomatoes and cucumbers was developed and validated. Vortex-assisted liquid-liquid extraction (VA-LLE) followed by dispersive solid-phase extraction (d-SPE) using graphitized carbon black (GCB) for cleanup was used before LC-MS/MS analysis. Different parameters were optimized, including the type and volume of extractants, vortex time, and the type and amount of adsorbents used for cleanup. The evaluation showed that the method has excellent linearity (R2 ≥ 0.994). The recovered 8 BPUs insecticides from spiked tomato and cucumber samples at 0.01, 0.05, and 0.25 mg kg−1 ranged from 83.2 to 105.2%, with RSD of 4.9–14.6%. The limits of quantitation (LOQs) were 0.0025 mg kg−1 (0.005 mg kg−1 for lufenuron). Within-day repeatability ranged from 3.9 to 13.9%, while between-day repeatability ranged from 8.9% to 17.7%. The optimized method was used to analyze 100 samples of tomatoes and cucumbers marketed in Saudi Arabia.