Recent developments of liquid-phase microextraction techniques directly combined with ESI- and MALDI-mass spectrometric techniques for organic and biomolecule assays

Abstract

The development of rapid, simple and reduced solvent consumption techniques for sample preparation is important for the isolation and preconcentration of organic and biomolecules from complex matrices. Miniaturized solvent-based extraction techniques have been intensively applied as sample pretreatment tools for the preconcentration of biomolecules from biological samples prior to their identification by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This review provides an overview of miniaturized solvent extraction methods and their efficient extraction of trace or ultra-trace analytes and their identification by MALDI-MS. We discuss the recent developments of miniaturized liquid-phase extraction approaches, such as liquid-phase microextraction (LPME) and single-drop microextraction (SDME) techniques, for organic and biomolecule pretreatment prior to MALDI-MS analysis. We also provide an update on the state-of-the-art and promising prospects of LPME techniques directly combined with ESI- and MALDI-MS techniques for the analysis of trace levels of organic and biomolecules in complex matrices. We also outline the advances of using liquid microjunction surface sampling probes coupled with MS for trace level analyte assays. Nanoparticle-assisted microextraction coupled with MALDI-MS for organic and biomolecule analysis, and the future trends of potential LPME applications are also highlighted.