Matrix Assisted Ionization in Vacuum, a Sensitive and Widely Applicable Ionization Method for Mass Spectrometry

  • Sarah TrimpinEmail author
  • Ellen D. Inutan
Research Article


An astonishingly simple new method to produce gas-phase ions of small molecules as well as proteins from the solid state under cold vacuum conditions is described. This matrix assisted ionization vacuum (MAIV) mass spectrometry (MS) method produces multiply charged ions similar to those that typify electrospray ionization (ESI) and uses sample preparation methods that are nearly identical to matrix-assisted laser desorption/ionization (MALDI). Unlike these established methods, MAIV does not require a laser or voltage for ionization, and unlike the recently introduced matrix assisted ionization inlet method, does not require added heat. MAIV-MS requires only introduction of a crystalline mixture of the analyte incorporated with a suitable small molecule matrix compound such as 3-nitrobenzonitrile directly to the vacuum of the mass spectrometer. Vacuum intermediate pressure MALDI sources and modified ESI sources successfully produce ions for analysis by MS with this method. As in ESI-MS, ion formation is continuous and, without a laser, little chemical background is observed. MAIV, operating from a surface offers the possibility of significantly improved sensitivity relative to atmospheric pressure ionization because ions are produced in the vacuum region of the mass spectrometer eliminating losses associated with ion transfer from atmospheric pressure to vacuum. Mechanistic aspects and potential applications for this new ionization method are discussed.

Key words

Matrix assisted ionization vacuum 3-Nitrobenzonitrile Coumarin Sublimation Triboluminescence Ionization mechanism Positive Negative Multiply and singly charged Fatty acids Drugs Lipids Proteins Polymers Carbohydrates TLC plates Glass tubes 



NSF CAREER 0955975, ASMS Research Award (Waters Co.), DuPont (Young Professor Award), Eli Lilly (Young Investigator Award in Analytical Chemistry), Waters Co. (COI program), and Schaap Faculty Scholar (to S.T.), and Schaap Graduate Fellow (to E.D.I.) are acknowledged. The authors are grateful for Professor Hendrickson (WSU) and Professor McEwen (USP) for valuable feedback on this manuscript.

Supplementary material

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Copyright information

© American Society for Mass Spectrometry 2013

Authors and Affiliations

  1. 1.Department of ChemistryWayne State UniversityDetroitUSA

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