Chitosan-based emulsive liquid-liquid microextraction for the determination of strobilurin fungicides in water samples.

Strobilurin fungicides are widely used pesticides globally; however, their residues pose a risk to environmental safety and human health. This study aimed to develop a rapid and green method for detecting strobilurin fungicide residues. Chitosan and magnetic deep eutectic solvent-based emulsive liquid-liquid microextraction method combined with high-performance liquid chromatography was developed to determine strobilurin fungicides in water samples. A high-concentration oil-in-water emulsion containing chitosan solution and extractant was formulated, followed by the addition of samples to form a low-concentration oil-in-water emulsion to complete the rapid pretreatment, therefore solving the limitation of emulsive liquid-liquid microextraction in the inapplicability of extractants. Traditional microextraction required toxic solvents and complex equipment to facilitate the dispersion of extractants, whereas this study used only chitosan solution to aid in emulsifying extractants. The new green magnetic deep eutectic solvent synthesized by tetraoctylammonium bromide, ferric chloride, and oleic acid was used instead of toxic extractants. An external magnetic field assisted the extractant phase collection, which shortened the separation time. Under optimal conditions, the recovery of this method was 83.3 %-107.4 %, the limit of detection was 0.0010-0.0021 mg L, and the coefficient of determination was >0.994. This rapid, green, simple, and efficient chitosan-based microextraction method could detect strobilurin fungicide residues in water samples because of its enhanced compatibility with hydrophobicity extractants.