Development of pH-controlled emulsive liquid-liquid microextraction for pyrethroid pesticide analysis in...

This study developed a rapid method for detecting pyrethroid pesticide residues using emulsive liquid-liquid microextraction (ELLME) coupled with high-performance liquid chromatography. In the ELLME, oleic acid (extractant) was mixed with an alkaline solution to generate an oil-in-water emulsion, which was subsequently added to the sample. This technique enabled rapid emulsification and extraction within 1 min without requiring any complex extraction devices. Subsequently, an acidic solution was introduced to induce immediate demulsification, achieving complete phase separation of oleic acid within 10 s, thereby eliminating the need for time-consuming centrifugation. This method operates based on the principle of pH-dependent modulation of oleate anion formation and emulsification, facilitating rapid extraction and efficient phase separation. Density functional theory calculations indicated that the van der Waals interactions predominantly governed the extraction mechanism. Five evaluation approaches were used to demonstrate the environmental sustainability of the extraction. When applied to environmental and food samples, the method demonstrated a satisfactory linearity range (0.005-0.5 mg L^-1), recoveries (85.8 %-100.8 %), and relative standard deviations (0.6 %-6.5 %), confirming good accuracy and reproducibility. This approach provides a potential solution for rapid, simple, and environmentally sustainable monitoring of pyrethroid pesticide residues.