Oxidation Artifacts in the Electrospray Mass Spectrometry of Aβ Peptide

• Published in: Analytical chemistry (Washington) Vol. 79; no. 5; pp. 2031 - 2036
• Main Authors: Chen, Maolian, Cook, Kelsey D
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-03-2007
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods; Sensitivity; Corrosion; Peptides; Stainless steel; Methionine; Sulfoxide; Artefact; Oxidation; Sampling; Electrochemical reaction; Mass spectrometry; Electrospray
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac061743r

Gradual corrosion of stainless steel electrospray emitters under conditions of normal use generates surface irregularities that can promote electrical discharge. The increased emission current affects the electrochemical reactions associated with the spray process. When sampling the peptide Aβ(1−40), this is manifest by oxidation of methionine at position 35 to methionine sulfoxide. The resultant mass shift and reduced sensitivity can adversely affect H/D exchange experiments. These effects can be avoided by adding a redox buffer or (preferably) by repolishing the emitter, especially to a rounded geometry.