Peptide Fragmentation Assisted by Surfaces Treated with a Low‐Temperature Plasma in NanoESI

A softy toughens up: When a nanoelectrospray (nanoESI) emitter was exposed first to a helium plasma (see illustration of experimental setup), ESI, a widely accepted “soft” ionization technique, caused significant and useful peptide fragmentation. The appearance of abundant peptide-fragment ions in the mass spectrum was ascribed to electrolyte release into the solution. Labile phosphate groups on the peptide were preserved during fragmentation.