Work

Miniaturized solid-liquid extraction with low-temperature partitioning for determining thiamethoxam residues in soil, bean leaves, and grains

Year: 2026

Type: article

Abstract: Monitoring pesticide residues in complex agricultural matrices requires analytical methods that combine robustness, sensitivity, and operational simplicity. This study proposes solid-liquid extraction with low-temperature partitioning (SLE-LTP) as a unified strategy for determining thiamethoxam residues in soil, bean leaves, and bean grains, followed by HPLC-DAD analysis. The methods were optimized using sample masses of 1000 mg for soil, 100 mg for leaves, and 500 mg for grains, with 4 mL of extraction solvent for all matrices. Under optimized conditions, recoveries ranged from 82.6 to 98.6%, with limits of quantification of 1 μg kg −1 for soil, 10 μg kg −1 for leaves, and 2 μg kg −1 for grains. The LOQ for bean grains was below the maximum residue limits established by the European Union (10 μg kg −1 ) and Brazilian regulations (20 μg kg −1 ). Precision (RSD < 10%), low expanded uncertainties (< 17%), and high robustness confirmed the reliability of the proposed methods according to international validation guidelines. The validated methods were subsequently applied to samples from a controlled bean cultivation experiment. Thiamethoxam residues were detected in soil only during the first 30 days and in leaves only after foliar application, with no thiamethoxam residues above the method LOQ detected in bean grains. These results demonstrate the applicability of SLE-LTP for thiamethoxam monitoring in soil and bean tissues under the cultivation conditions studied, while requiring low sample and solvent amounts and no additional extract cleanup steps.

Source: Microchemical Journal

DOI: 10.1016/j.microc.2026.119918