Development of desorption electrospray ionization (DESI) mass spectrometry and its application to direct biological tissue analysis and molecular imaging

A new desorption ionization (DI) method for mass spectrometry is introduced to allow the analysis of samples present on or near surfaces under ambient conditions. This new method is termed desorption electrospray ionization (DESI) and allows experiments to be conducted at atmospheric pressure, unlike traditional DI techniques. The utility of this method is explored in several examples; first by analyzing peptides, proteins, as well as small organic molecules and exploring the relationships among the various experimental variables; second, by examining intact, biological tissue for the analysis of lipids and metabolites; third, developing the capabilities for molecular imaging of surfaces; and fourth, by demonstrating molecular imaging of an ink pattern written onto photographic paper and of intact, biological tissues including those from cancerous tissues