P104-M Comparison between Sample Preparation On Chip (SPOC) and Off-Line MALDI-MS Sample-Preparation Approaches for Sample Clean-Up and IMAC Enrichment

Optimized sample preparation is crucial for successful and sensitive detection of peptides by MALDI-TOF MS. In particular, the protein identification of low femtomole amounts of analyte requires further clean-up and concentrating steps to acquire significant spectra. This aspect is even more pronounced if the analysis of post-translational modifications is the goal. A prominent example is the mapping of protein phosphorylation sites, which is often hampered by the lack of phosphopeptides in spectra of crude digests. For that reason, very often micro-columns filled with reversed-phase material for clean-up, or IMAC or TiO2 resins for phosphopeptide enrichment, are employed prior to MALDI-MS analysis.