Low-density solvent based vortex-assisted surfactant enhanced emulsification microextraction with a home-made extraction device for the determination of four herbicide residues in river water
A vortex-assisted surfactant-enhanced emulsification microextraction method was developed for the determination of four acetanilide herbicides in river water. Non-chlorinated solvents with a lower density than water were used as the extraction solvent. With the help of vortex assistance and surfactant emulsification, the extraction solvent could be dispersed into the sample solution without the use of an organic dispersive solvent. After centrifugation, the extraction solvent drop floating on the top of the sample solution was collected using the unique home-made device based on a flexible plastic Pasteur pipette and iron stands. The factors which might affect the extraction efficiencies were investigated including the type and volume of extraction solvent, the type and concentration of surfactant, the vortex time, and pH of the sample. Under optimized conditions, the proposed method provided a good linearity in the range of 0.5–20 μg L−1 and 1–40 μg L−1, respectively. The limit of detection of the method was in the range of 0.15–0.30 μg L−1 and the limit of quantification was in the range of 0.5–1.0 μg L−1. Recoveries for each target herbicide were 85.7–113.3% with good repeatability (RSDs below 9.9%, n = 5) in the river water sample.