Emulsion-based liquid-phase microextraction: a review

Abstract

In the past decade, liquid-phase microextraction (LPME), which can also be called solvent microextraction, has emerged as a minimal organic solvent-based sample preparation approach. The main advantages of this method include versatility, simplicity and effectiveness of its extraction procedures at reducing sample complexity, as well as the convenience of liquid sample concentration and injection techniques. LPME is based on the distribution of analytes between the organic solvent and the aqueous solution. Hitherto, several different LPME modes have been developed. Some of the described methodologies usually offer slow extraction kinetics due to the low contact surface between the sample and the extractant phase. Since the introduction of dispersive liquid–liquid microextraction, a number of studies have been focused on the features of emulsification in preconcentration techniques. Emulsification enhances the surface area between the extraction solvent and aqueous sample by the efficient dispersion (chemically assisted or by the use of an external energy source) of the extractant in the sample. In this paper we review the emulsification-based liquid-phase sample preparation techniques. A brief practical and theoretical description of each technique and some applications are given.