Sodium alginate-fortified emulsive liquid-liquid microextraction for detecting succinate dehydrogenase inhibitor fungicides in water, juice, and wine

A method of sodium alginate-fortified emulsive liquid-liquid microextraction (FELLME) combined with ultra-high performance liquid chromatography was developed to detect succinate dehydrogenase inhibitor (SDHI) fungicides in water, juice, and wine. The oleic acid as extractant and sodium alginate solution as emulsifier were mixed to form an emulsion to extract SDHIs. Subsequently, it was demulsified by adding magnesium sulfate solution as a demulsifier. All extractants, emulsifiers, and demulsifiers were natural products derived from seaweed. As a long-chain fatty acid, oleic acid exhibits strong hydrophobic properties that can enhance pesticide extraction; however, its application as an extractant in ELLME is limited. Sodium alginate has hydrophilic and hydrophobic groups and a three-dimensional network structure, which can enhance the emulsification process, improve the compatibility of green solvents with ELLME. The pretreatment process does not require complex equipment, including vortex, ultrasound, and centrifuge for extraction and separation. The possible extraction mechanism was analyzed through theoretical calculations. The limit of detection and quantification were 0.1-0.3 and 0.4-1.0 ng mL^-1, respectively. The recoveries were 80.1 %-95.3 %, and the relative standard deviations were 1.5 %-7.2 %. This fortified method is anticipated to expand the applications of ELLME in pesticide analysis of food samples.