Low-density solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction and its application

For the first time, the low-density solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction, followed by GC-flame photometric detection has been developed for the determination of eight organophosphorus pesticides in aqueous samples. A small volume of organic extraction solvent (toluene) was dispersed into the aqueous samples by the assistance of surfactant and vortex agitator. The extraction was performed in a special disposable polyethylene pipette, allowing using the reagents with lower density than water as extraction solvents. The influence parameters were systemically investigated and optimized: toluene (30 L) and Triton X-100 (0.2 mmol/L) were used as the extraction solvent and the surfactant, respectively, and the extraction was performed for 1 min under room temperature without adding sodium chloride. Under the optimum conditions, the validation parameters such as the RSD (n = 6; 2.1-11.3%), LOD (0.005 and 0.05 g/L), and linear range (0.1-50.0 g/L with correlation coefficients (0.9958-0.9992) showed the method was satisfying. The proposed method has been successfully applied to the determination of the organophosphorus pesticides in real samples with recoveries between 82.8 and 100.2%.