Figure 6.

(a) The number of total a^•- and x-type fragment ions generated from the peptides common to both C₁₆H₁₀^•+ (blue) and SF₅^•+ (orange) analyses are shown. For both fragment ion types SF₅^•+ produces the greater number of sequencing ions and the percent gains over the number of ions from C₁₆H₁₀^•+ analyses are shown in bold. Panel (b) compares the percentage of a^•- and x-type product ions from Panel (a) that have a corresponding neutral loss of CO₂. (c) Despite the small increase in CO₂ neutral losses observed, incorporating CO₂ neutral losses from a^•- and x-type product ions as fragment ion types to query in a database search does not improve peptide identifications over using standard a^•- and x-type product ions only for the SF₅^•+ data. The combination of product ion types used in the database searches are shown in black at the top, and the number of identified peptide spectral matches are shown in orange at the bottom. Similar results were obtained with the C₁₆H₁₀^•+ analyses (data not shown).