On-Probe Solid-Phase Extraction/MALDI-MS Using Ion-Pairing Interactions for the Cleanup of Peptides and Proteins

• Published in: Analytical chemistry (Washington) Vol. 70; no. 18; pp. 3757 - 3761
• Main Authors: Warren, Maria Esteban, Brockman, Adam H, Orlando, Ron
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15-09-1998
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chemistry; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; Indicators and Reagents; Ions; Peptides; Peptides - analysis; Peptides - isolation & purification; Proteins; Proteins - analysis; Proteins - isolation & purification; Scientific imaging; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Photoionization; Mass spectrometry; Laser desorption; Electrospray; Protein; Analytical method
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac980210i

Samples originating from biological sources often contain a complex mixture of inorganic salts, buffers, chaotropic agents, surfactants/detergents, preservatives, and other solubilizing agents. However, the presence of these contaminants virtually ensures the failure of any subsequent analysis of the sample by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Sample cleanup procedures, therefore, must be performed prior to MALDI-MS analysis. This paper reports a probe-surface derivatization method that greatly simplifies this sample preparation process. MALDI probes possessing self-assembled monolayers (SAMs) terminated with ionic functional groups can rapidly extract peptides/proteins via ionic interactions from ≤1-μL volumes of sample solutions placed directly on their surface. We have found that MALDI probes modified in this manner are a practical solution for analyzing very small volumes of peptide/protein solutions contaminated with high levels of inorganic salts, buffers, detergents, chaotropic agents, and other solubilizing agents.