Development of a new emulsification microextraction method based on solidification of settled organic drop: application of a novel ultra-hydrophobic tailor-made deep eutectic solvent

Abstract

In this research, a new microextraction method based on the solidification of settled organic drop (SSOD) was developed by coupling a novel tailor-made ultra-hydrophobic deep eutectic solvent (DES) with effervescence assisted emulsification microextraction. The deep eutectic solvent of salol/DL-menthol (1 : 1) was used as an extraction solvent in this study. It has a low melting/freezing point, low viscosity, ultra-hydrophobicity and bio-compatibility. An effervescent tablet was prepared by mixing the DES and effervescence precursors. Generation of CO₂ bubbles due to effervescence distributes the DES homogenously into an aqueous sample, which enhances the mass transfer for target analytes to extract into the fine DES droplets. After centrifugation of the cloudy solution at 20 °C, the settled solidified extractant was isolated from the aqueous solution simply by decanting the tube. Predominant experimental variables affecting the extraction efficiency of explosives were evaluated. This method was coupled with high performance liquid chromatography-ultra violet detection for the analysis of nitroaromatic compounds. Under the optimized conditions, the limits of detection achieved were in the range of 0.03–0.05 μg L⁻¹. The enrichment factors were between 576 and 702 and the relative standard deviations were <10%. The analysis of eight nitroaromatic pollutants in water samples gave acceptable recoveries ranging from 89 to 105%.