Development and validation of one-step ultrasound-assisted extraction for simultaneous determination of multiclass fungicides in soils

Abstract

A rapid, efficient, and simple one-step ultrasoundassisted extraction (UAE) method was developed for the analysis of seven fungicides (cymoxanil, metalaxyl, mandipropamid, folpet, chlorothalonil, kresoxim-methyl, and famoxadone) in horticultural soils. Analytes in the samples were determined by HPLC with variable wavelength detection. Key parameters that influence the UAE procedure were optimized, such as the nature and volume of extraction solvent, number of sonication steps, and sonication time. The highest extraction efficiencies in the range of 61.1-87.8% were obtained by using only 7.5 mL of ethyl acetate-hexane (1 + 1, v/v) and sonicating for 10 min. At 0.5 and 2.0 μg/g fortification levels, satisfactory recoveries (>60%) with RSD <13% were obtained for each analyte, except for folpet (>52%). The method was linear over the range of 0.005 to 10 μg/g and the correlation coefficients (r2) obtained ranged from 0.9955 to 0.9992. The LODs (S/N = 3) varied from 0.0015 to 0.006 μg/g. The proposed UAE procedure was compared to classical extractions (shake-flask and Soxhlet extraction) and showed satisfactory extraction efficiencies using shorter time and smaller amounts of organic solvents, thereby minimizing the costs of the analysis and the disposal of waste solvent.