Desorption Electrospray Ionization Mass Spectrometry

Abstract Desorption electrospray ionization is an atmospheric pressure surface sampling/ionization technique for mass spectrometry. Desorption electrospray ionization consists of a pneumatically assisted electrospray ionization source, or emitter, held at a fixed angle above a sample surface. A high‐velocity spray consisting of charged solvent microdroplets in a gas stream emerges from the source and impacts the sample surface. The spray solubilizes any analyte molecules that are present and creates charged analyte‐containing secondary droplets that are drawn into the inlet of the mass spectrometer through an atmospheric pressure interface. Ionization may occur in a fashion similar to that involved in electrospray ionization, although other ionization mechanisms may also play a role. Analytes that can be detected using electrospray ionization mass spectrometry can also be detected using desorption electrospray ionization mass spectrometry. Desorption electrospray ionization can be used to rapidly sample surfaces ranging from living tissues to metal oxides for a diverse variety of analytes, and has been used for such important applications as direct determination of analytes present in complex matrices, analyses of biological tissues and forensically relevant materials, readout of thin‐layer chromatography plates, and chemical imaging. As in electrospray ionization, multiply‐charged ions are formed during desorption electrospray ionization, allowing for the detection of analytes having molecular weight ranges beyond the m / z range of the mass analyzer.