Da-Geon Lee

A common quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatography–tandem mass spectrometry (GC–MS/MS) was evaluated and applied to survey pesticide residues in minor livestock products and other animal-derived foods marketed in Korea. Performance was assessed in lamb, duck meat, quail egg, mealworm, and edible frog for 150 LC–MS/MS and 75 GC–MS/MS target analytes, including metabolites and isomers. In each matrix, limits of quantitation (LOQs) were ≤0.01 mg/kg for at least 96% of target analytes on each platform. Most analytes met the linearity criterion, and most with LOQs at or below each fortification level met recovery and precision criteria; recurrent low recoveries were most evident for some LC–MS/MS analytes in lamb. Among 90 market samples from 13 food categories, four target analytes were quantified, each in a different sample. Under adult intake assumptions for the surveyed foods, including surrogate and default values, chronic exposure estimates for the four detected pesticides were below their acceptable daily intakes, and acute estimates for the two pesticides with established acute reference doses were below these values. This study provides performance data for the directly evaluated matrices and commodity-specific residue data for the surveyed foods.

A method for quantifying tebufenpyrad residues in greenhouse sandy loam soils was developed and validated. Given the strong sorption (high K_oc) 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.

Pencycuron is a fungicide whose maximum residue limit (MRL) in eggplant is either set at very low levels (0.02 mg/kg in European Union) or remains unestablished in many countries, necessitating stringent pesticide management. To enable timely interventions by farmers and regulators, pre-harvest residue limits (PHRLs) propose maximum allowable pesticide concentrations for each day during the pre-harvest period. An analytical method was developed to conduct residue determination trials, demonstrating that graphitized carbon black (GCB) effectively removes eggplant matrices during sample preparation. The LC-MS/MS method was established with a limit of quantification (LOQ) of 0.005 mg/kg, recovery rates ranging from 102.6% to 106.1% with relative standard deviation (RSD; 2.3–6.4%), and a matrix effect (%ME) of +8.1%. Residue analysis revealed a concentration of 0.045 mg/kg at 0 days after treatment (DAT), decreasing to 0.006 mg/kg at 14 DAT. The residue dynamics followed a first-order kinetic model, as confirmed by the F-test, with a rate constant of 0.1405. Therefore, the half-life was determined to be 4.9 d. Based on the MRL value of 0.02 mg/kg at 0 days before harvest (DBH), the PHRL was determined using both k and k_min, resulting in values of 0.04 mg/kg and 0.02 mg/kg at 5 days and 0.08 mg/kg and 0.03 mg/kg at 10 DBH, respectively. Using k_min yields more conservative results, which ensures food safety under conditions of slower degradation rates.