Current trends on microextraction by packed sorbent - fundamentals, application fields, innovative improvements and future applications

MEPS, acronymous of microextraction by packed sorbent, is a simple, fast and user- and environmental-friendly minituarization of the popular solid-phase extraction technique (SPE). In fact, it has been widely shown that MEPS can easily replace SPE for most, if not all, previous applications. And can attain this with obvious gains in sample and solvent usuage, that are greatly reduced without compromise the extraction efficiency. Furthermore, MEPS can be operated with semiautomatic electronic syringes, making it very reliable and versitile, particularly to handle very low and very high sample volumes. This review will focus the strengths and weaknesses of this technique and the different MEPS architectures commercially available in the context of the MEPS applications reported in the last five years. Addtionally, innovative improvements will be highlighted, particularly those related with new applications and recent MEPS configurations and sorbents, as the controlled directional flow or the innovative µSPEed variant.