Influence of Na+ and K+ Concentration in solvents on Mass Spectra of Peptides in LC–ESI-MS
The effect of dispersing a solvent into charged droplets, when applying a high electric potential to an effluent capillary, was first described by Zeleny in 1917 (1). It was investigated in more detail in 1955 by Drozin (2) and used in pioneering work for an electrospray interface by Dole et al (3,4). This was continued in 1984 by Yamashita and Fenn (5,6), which finally resulted in a description of an LC–MS interface in 1985 (7). Today electrospray ionization (ESI) is the most widely used ionization technique in LC–MS. This is especially true in protein mass spectrometry, where series of multiply charged ions are observed and used to determine the molecular mass (8,9). Furthermore, after tryptic digestion, the resulting peptides can be measured with LC–ESI-MS, to obtain amino acid sequence information after a second MS/MS-step (10–14).
