Application of vesicular coacervate phase for microextraction based on solidification of floating drop

A new, efficient and environmentally friendly method for the analysis of parabens as model compounds was developed using solidified floating vesicular coacervative drop microextraction (SFVCDME). A supramolecular solvent consisting of vesicles of decanoic acid in the nano- and microscale regimes was firstly used as the solvent in solidification of floating drop microextraction. The solvent was produced from the coacervation of decanoic acid aqueous vesicles in the presence of tetrabutylammonium (Bu4N+). Methylparaben (MP), ethylparaben (EP), and propylparaben (PP) were extracted on the basis of hydrophobic and pi-cation interactions and the formation of hydrogen bonds. Microliter volume of vesicular coacervative droplet was delivered to the surface of the aqueous sample, and the sample was stirred for a desired time. The sample vial was cooled by immersing it into an ice bath for 3 min. The solidified solvent was transferred into a suitable vial and melted immediately. Twenty microliter of the vesicular coacervative solvent was directly injected to high-performance liquid chromatography-ultraviolet detection, with no need to dilution or solvent evaporation. Several parameters affecting the microextraction efficiency including sample temperature, stirring rate, pH, salt effect, volume of the solvent and extraction time were investigated and optimized. Under optimum conditions, preconcentration factors and relative recoveries of the studied compounds were obtained in the range of 81-174 and 91-108%, respectively: and the performance of the method was comparable with that of solid-phase extraction as the reference method. (C) 2012 Elsevier B.V. All rights reserved.