Hollow-Fibre Liquid-Phase Microextraction

This chapter discusses microextraction using liquid membranes immobilized in a porous support membrane, including two- and three-phase hollow fibre liquid-phase microextraction (HF-LPME), 96-well LPME (or parallel artificial liquid membrane extraction (PALME)), and electromembrane extraction (EME). These techniques are essentially two- or three-phase liquid extraction systems, but downscaled to the level where the consumption of organic solvent per sample is less than 10 µL. Such microextraction systems are interesting for several reasons. First, they are ideal for green sample preparation, and therefore they are expected to be important in the near future in the context of sustainability. In addition, due to size and technical arrangement, they are easily implemented in microchip systems. Recently, several research papers have been investigating such microchip systems in combination with smartphone detection. This research has the potential to move analytical measurements out of today’s specialized laboratories. The fundamentals are discussed, to underline that microextraction with liquid membranes can be performed in partition-based systems, or in systems controlled by an external electrical field. In addition, this chapter discusses novel developments and new applications, based on examples from recent literature. The chapter is not comprehensive but is intended to give a flavour of the field.