What is the Profile Generation Model (PGM)?
The profile generation model written in QuickBASIC 4.5 helps plan data acquisitions and automatically interprets the data obtained. For a low-mass ion (up to 150 amu) ICE usually determines its composition from its exact mass. For higher-mass ions, multiple possible compositions remain and the PGM then distinguishes between compositions based on the exact masses of the mass peak profiles higher in mass by +1 and +2 amu that arise from heavier isotopes of elements. For example, a carbon atom (C) can be 13C, which is 1.1% as abundant as 12C, an oxygen atom (O) can be 16O (99.762%), 17O (0.038%), or 18O (0.200%), a nitrogen atom (N) can be 14N (99.634%) or 15N (0.366%), and a sulfur atom (S) can be 32S (95.02%), 33S (0.75%), or 34S (4.21%). The PGM also uses the abundances of the +1 and +2 profiles relative to the ion’s abundance (relative abundances) to determine an ion’s composition. To understand how +1 and +2 profiles can distinguish between ions with the same nominal mass (rounded to
