Optimization and application of ultrasonic extraction and Soxhlet extraction followed by solid phase extraction for the determination of triazine pesticides in soil and sediment

Abstract

Ultrasonic extraction (UE) and Soxhlet extraction (SE) methods followed by clean up using solid phase extraction (SPE) have been developed and applied for the simultaneous analysis of five commonly used triazine pesticides. The SE and UE extraction parameters that affect the recovery of the analytes were optimized before the application of the methods to improve the analytes recoveries. The parameters optimized were extraction solvent, the volume of extraction solvent and extraction time for UE, extraction solvent and sample wetting for SE. The methods validation was performed using soil and sediment samples spiked with a known concentration of triazines mixture. The recoveries obtained were 70–100% and 71–87% for UE, and SE, respectively. The limits of detection (LOD) and limits of quantification (LOQ) ranged between 1.0–2.0 μg/kg and 3.2–6.1 μg/kg, 0.092–0.22 μg/kg and 0.28–0.69 μg/kg, for UE, and SE, respectively. A good precision with a relative standard (RSD) less than 10% in all compounds was achieved for all methods. SE showed to be more sensitive than UE, however, the recoveries for both methods were comparable. The optimized and validated methods were then applied to sediment and soil samples. The concentrations obtained were 1.1–123 μg/kg in sediment samples and 17–1017 μg/kg in soil samples. Simazine was found to be the most dominant triazine compound and it was above the maximum residual limits in Gilboa farm soil sample.