Synthetic peptide mass spectra

For example, Figure 8.17 shows the MALDI spectrum of a synthetic peptide with a molecular mass of 1984.2 Da. Two compounds appear next to the sought peptide. The mass difference between these two impurities and the synthetic peptide suggests that partial oxidation of methionine and glycine addition occurred during the synthesis. 

Figure 4. Partial view of the matrix-assisted laser desorption mass spectrum of the synthetic peptide ladder from 9 to 32 residues. The formation of aspartimide (loss of water, -18u) and the piperidine adduct (+67n) are strongly observed after the synthesis of 13 residues. The weak intensity of the peak corresponding to the 14 mer is due to the low amount of 14 mer added.

Mass calibration is relatively straightforward even though it does not follow a simple linear or square-root mass law. Figure 8.24 shows the product-ion mass spectrum obtained on the curved-field reflectron TOF for the synthetic peptide... 

FIGURE 10.13 MALDI reflectron TOF mass spectrum of partially hydrolyzed synthetic peptide EVRFMVSEIPEA. Reprinted with permission from reference 21. 

Figure 3 Partial CID-MS/MS spectrum obtained on a tandem 4-sector mass spectrometer for a 14-residue synthetic peptide. (A) without labels (B) and (C) with labels as indicated by asterisks.

Tandem Mass Spectrometry Tandem MS is an early technique that involves the isolation of a specific ion followed by its fragmentation, which occurs in a collision cell, resulting in a fragment ion spectrum. This technique has been satisfactorily used for the smdy of peptide sequences [41], but it can also be used for the analysis of synthetic polymers. 

---