Desorption-Enhanced QuEChERS Extraction of Tebufenpyrad from Soil and Its Greenhouse Dissipation

A method for quantifying tebufenpyrad residues in greenhouse sandy loam soils was developed and validated. Given the strong sorption (high Koc) of tebufenpyrad to mineral–organic domains in soils, desorption-limited and partially bound residues may occur, so sample preparation methods should actively promote desorption to minimize underestimation. The QuEChERS extraction procedure was optimized by adjusting pre-wetting volume and aqueous medium to enhance desorption prior to salt-induced acetonitrile partitioning. Pre-wetting volume markedly affected phase separation and recovery: acceptable ranges were 80.2–82.0% at 5–10 mL, 94.6% at 15 mL, and 99.1% at 20 mL, while a supra-quantitative value of 119.6% was observed at 25 mL, likely due to salt-induced contraction of the acetonitrile layer, which artificially concentrates tebufenpyrad. Among pre-wetting reagents, 15 mL of 0.05% HCl yielded the highest desorption in field soil (0.20 mg/kg), compared with distilled water (0.13 mg/kg), formic acid (0.16 mg/kg), and EDTA (0.14–0.17 mg/kg). The final method employed 15 mL of 0.05% HCl for pre-wetting, followed by acetonitrile extraction and MgSO4/NaCl partitioning. Linearity (r2 = 0.9990) was achieved over 1.25 to 100 ng/mL, with an LOQ of 0.005 mg/kg and average recoveries of 86.7%, 99.8%, and 98.5% at 0.01, 0.1, and 30 mg/kg, respectively (RSD ≤ 6.2%), satisfying SANTE criteria. In greenhouse soil, residues declined from 1.9 to 0.3 mg/kg at the recommended rate (1×) and from 4.8 to 0.7 mg/kg at the doubled rate (2×) within 46 d (DT50 ≈ 20 d). This validated QuEChERS method provides a reliable analytical basis for evaluating tebufenpyrad dissipation in soil.