Agar films containing silver nanoparticles as new supports for electromembrane extraction.

A new support containing silver nanoparticles to assist electromembrane extraction (EME) procedures is proposed. For the first time, synthesized agar films containing silver nanoparticles (AgNPs) have been used as a support for liquid membranes in EME. Agarose films of 20 µm thickness containing 107.9 mg Ag/g agar were synthesized and characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM), showing isolated spherical silver nanoparticles of 20-30 nm diameter with homogeneous distribution. Nanometallic films were cut and glued to narrow bore glass tubes and used as supports for a dihexyl ether liquid membrane for use in an EME procedure. EME conditions were optimized and applied to the extraction of selected non-steroidal anti-inflammatory drugs (NSAIDs). The results were compared to those using polypropylene membranes (450 µm and 100 µm thickness), achieving 10- to 70-fold higher extraction efficiency. This article opens a new line of research into electrically assisted microextraction systems by combining other possible kinds of nanometallic films, including different metals, film functionalization through metallic NPs, and the use of low polarity solvents. Also, very low currents are obtained during the extraction process, which lead to high electromigration of the analytes.

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.