Fragmentation patterns of protonated amino acids formed by atmospheric pressure chemical ionization.

Rationale: Dissociation reactions of protonated amino acids (AAs) can be used as models for the fragmentation of protonated peptides. Atmospheric pressure chemical ionization mass spectrometry (APCI-MS) provides a great deal of structural information in a short analysis time.

Methods: In APCI-MS, the fragmentation patterns can be obtained by varying the cone voltage and some fragment ions are produced that can be used to identify the structure of an analyte.