Studies on the extraction of sulfonamides from agricultural soils

The extraction of six sulfonamides (sulfadiazine, sulfadimidine, sulfathiazole, sulfachloropiridazine, sulfadimethoxine, and sulfaquinoxaline) from soils with different physicochemical characteristics and at several aging times was investigated. Conventional mechanical shaking, microwave-assisted extraction, ultrasound probe-assisted extraction and pressurized liquid extraction techniques were evaluated. The four techniques provided similar results when applied to freshly contaminated soils. However, microwave-assisted extraction was the most suitable to extract sulfonamide aged residues from soils. Microwave-assisted extraction was applied to eight soils aged for 3 months, using acetonitrile:buffer pH 9 (20:80) as the extraction solvent, and recoveries ranged from 15–25% for STZ to 42–64% for SDM.