Development of a one-step microwave-assisted extraction procedure for highly efficient extraction of multiclass fungicides in soils

Abstract

A one-step microwave-assisted extraction (MAE) procedure for highly efficient multiresidue extraction of seven fungicides (cymoxanil, metalaxyl, mandipropamid, folpet, chlorothalonil, kresoxim-methyl and famoxadone) in soil was developed. The trace residue levels in the soil were determined by high performance liquid chromatography (HPLC) with variable wavelength detection (VWD). Parameters affecting the MAE process such as the type and volume of the extraction solvent, irradiation power, temperature, irradiation time, moisture and salt addition were optimized. Under the optimal conditions, extraction efficiencies in the range of 72.4–99.4% were obtained for all the fungicides studied. The method was linear over the range of 0.01–10 μg g⁻¹ with correlation coefficients (r²) between 0.9989 and 0.9999. LODs (S/N = 3) and LOQs (S/N = 10) obtained varied from 0.0006 to 0.0015 μg g⁻¹ and from 0.002 to 0.005 μg g⁻¹, respectively. The proposed method has been successfully applied to the analysis of real soil samples and acceptable recoveries from 57.5 to 122% with RSDs ≤14% were obtained. The overall results have been compared with Soxhlet, shake-flask and ultrasonic solvent extraction techniques. Thus, the developed method could be efficiently used for selective extraction and determination of the target analytes from complex soil matrices.