Development of an easily adaptable, high sensitivity source for inlet ionization

Abstract

An unexpected ionization process was recently discovered for use in mass spectrometry in which no added energy is required to convert condensed-phase molecules to ESI-like gas-phase ions. This process offers the opportunity to greatly simplify ionization and reduce energy requirements for use with portable mass spectrometers. Here we designed and constructed minimal ion sources specifically for the new ionization methods, and demonstrate conversion of compounds directly to gas-phase ions with high sensitivity using matrix-assisted ionization without a laser, voltage, or heat. A variety of inlets and sample supports were tested for sample introduction with this minimalistic source, include a contactless ‘vacuum cleaner’ approach for analyzing samples as well as laser ablation for high spatial resolution. The analysis is astonishingly simple and the mass spectra surprisingly free of background ions. Analytes tested range from small molecules (e.g. drugs) to nonvolatile compounds (e.g. proteins). These developments are potentially useful in a variety of vendor-independent applications, especially where simplicity, miniaturization, or automation are desirable attributes.