Ionic liquids for mass spectrometry: Matrices, separation and microextraction

• Review the application of ionic liquids as matrices for MALDI.
• Report the ionic liquids progress for proteomics, biotechnology and analytical chemistry.
• Explore the pros and cons of ionic liquids for mass spectrometry.
• Discuss the progress of ionic liquids for separation and microextraction.
• Compare among organic, ionic liquids and nanoparticles.

Applications of ionic liquids (ILs) for mass spectrometry (MS) are a burgeoning area and are promising for real applications. However, the research of ILs for MS is in its infancy and there are a large potential for further applications under the ashes. This review article provided an overview of the current state and the research progress of ILs applications for MS. ILs offered several advantages, such as low vapor pressure, soft ionization, high sensitivity, better separation and microextraction, effectively disperse nanoparticles for nanoprobe technologies, and stable under vacuum and for storage in solution form, that leaded to several applications for MS and assured that ILs carry a brilliant future for analytical purposes. A plethora of ILs with different properties can be designed by various combinations of acid and base moieties and were applied as multifunctional materials. Thus, ILs provided many platforms such as green solvents for microextraction, stationary phases for separation and matrices for laser desorption/ionization mass spectromery (LDI-MS). Comparison among the organic matrices, ILs and nanoparticles were also highlighted.