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- Title
Influence of Na<sup>+</sup> and K<sup>+</sup> Concentration in Solvents on Mass Spectra of Peptides in LC/ESI-MS.
- Authors
Emmert, Joachim; Pfluger, Markus; Wahl, Fabian
- Abstract
The concentration dependent influence of Na+ and K+ ions on mass spectra of peptides is shown with human gastrin as a model peptide. With electrospray ionization the doubly charged protonated molecule ion [M+2H]2+ is normally the preferred ionization product. However, trace amounts of alkali metal ions already form clusters (adducts) with the peptide molecule, such as [M+H+Na]2+, which become dominating at higher concentrations, With Na+/K+ concentrations below 0.1 mg/kg (ppm) only a few clusters appear, which allow the correct doubly charged molecule ion to be assigned for a subsequent MS/MS experiment. With concentrations of 10 ppm and higher the alkali clusters become the most abundant peaks in the spectrum, and the absolute sensitivity is decreased by a factor of 5-10. Experiments were performed with water and water-methanol mixtures with a known Na+/K+ +content.
- Subjects
MASS spectrometry; ELECTRONS; IONS; SPECTRUM analysis; GASTROINTESTINAL hormones; SODIUM
- Publication
LC-GC Europe, 2004, Vol 17, Issue 12, p646
- ISSN
1471-6577
- Publication type
Article