Continuous electromembrane extraction coupled with mass spectrometry - Perspectives and challenges.

This tutorial discusses continuous electromembrane extraction (c-EME) coupled directly to mass spectrometry (MS), and the applicability of such systems for on-line and real-time monitoring of in-vitro drug metabolism. Parent drug substances and corresponding drug metabolites are extracted from the metabolic reaction mixture, through a supported liquid membrane (SLM), and into an acceptor solution on the other side. Extraction is accomplished using an external electrical field sustained over the SLM. The acceptor solution is continuously pumped into the mass spectrometer, and the decline of parent drug as well as the development of metabolites is followed directly with the mass spectrometer. The purpose of the extraction is to avoid proteins and salts from the reaction mixture from entering the mass spectrometer. This tutorial first discusses the principles and theory of operation. Second, technical development is highlighted with special focus on major challenges associated with c-EME-MS systems. Third, operational parameters and performance are discussed, and finally future perspectives and challenges are considered.