Matrix Assisted Ionization Vacuum (MAIV), a New Ionization Method for Biological Materials Analysis Using Mass Spectrometry

Sarah Trimpin,Ellen D. Inutan

doi:10.1074/mcp.m112.023663

Abstract

The introduction of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) for the mass spectrometric analysis of peptides and proteins had a dramatic impact on biological science. We now report that a wide variety of compounds, including peptides, proteins, and protein complexes, are transported directly from a solid-state small molecule matrix to gas-phase ions when placed into the vacuum of a mass spectrometer without the use of high voltage, a laser, or added heat. This ionization process produces ions having charge states similar to ESI, making the method applicable for high performance mass spectrometers designed for atmospheric pressure ionization. We demonstrate highly sensitive ionization using intermediate pressure MALDI and modified ESI sources. This matrix and vacuum assisted soft ionization method is suitable for the direct surface analysis of biological materials, including tissue, via mass spectrometry.

Highlights

Author’s Choice—Final version full access. 1 The abbreviations used are: 3-NBN, 3-nitrobenzonitrile; ACN, acetonitrile; BSA, bovine serum albumin; ESI, electrospray ionization; ETD, electron transfer dissociation; IMS, ion mobility spectrometry; Matrix assisted ionization vacuum (MAIV), matrix assisted ionization vacuum; matrix-assisted laser desorption/ionization (MALDI), matrixassisted laser desorption/ionization; MS, mass spectrometry; TOF, time-of-flight
MALDI is of limited utility on high performance mass-to-charge (m/z) analyzers because of mass range issues related to the formation of singly charged ions, which produce few fragment ions for structural characterization [8]
ESI is limited for surface characterization, requiring approaches such as desorption-ESI [15] and laser ablation ESI [16], ionization methods that produce multiply charged ions but are not compatible with analyses of larger proteins or fragile complexes

Summary

Introduction

Author’s Choice—Final version full access. 1 The abbreviations used are: 3-NBN, 3-nitrobenzonitrile; ACN, acetonitrile; BSA, bovine serum albumin; ESI, electrospray ionization; ETD, electron transfer dissociation; IMS, ion mobility spectrometry; MAIV, matrix assisted ionization vacuum; MALDI, matrixassisted laser desorption/ionization; MS, mass spectrometry; TOF, time-of-flight. 1 The abbreviations used are: 3-NBN, 3-nitrobenzonitrile; ACN, acetonitrile; BSA, bovine serum albumin; ESI, electrospray ionization; ETD, electron transfer dissociation; IMS, ion mobility spectrometry; MAIV, matrix assisted ionization vacuum; MALDI, matrixassisted laser desorption/ionization; MS, mass spectrometry; TOF, time-of-flight.

Results

Conclusion